On Thu, 26 Jan 2012 00:28:01 +0000, The Natural Philosopher wrote:
To counter this, modern engines use platinum tipped
spark plug electrodes at greater expense and reduced spark energy
capacity. There is also fancy electronic mapping to get the best out
of the engine with these stupid plugs. There is no need to dress the
electrodes every 3000 miles to maximise acceleration, you can't, the
electrodes are already at a poor performing level and the majority of
engine management units won't self modify to compensate for the
improvement even if you do put in the regular electrode plugs.

Complete toss from beginning to end.

I think some of the punctuation in the middle was OK.

In article
,
thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require a
reversed coil connection.


of course
there may have mbeen changes in the last 8 years which overcome the
problem, but it seems it's all been hushed up.

The Ford EDIS system I've referred to is much older than 8 years. Dates
back to the last century. But wasted spark has been used long before that.
And it's not much used today on car engines. It's beauty was it only
required a crank signal. Full sequential requires a camshaft one too. As
electronics have come down in price, most now use one coil per cylinder
and a combined trigger from crank and cam.

--
*If you tell the truth, you don't have to remember anything.*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article
,
thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require a
reversed coil connection.

For once I agree with you. Its arrant nonsense

The sparks are always of the same polarity. That's according to how they
are wired up. The alternate spark only is a matter of time, not polarity.



of course
there may have mbeen changes in the last 8 years which overcome the
problem, but it seems it's all been hushed up.

The Ford EDIS system I've referred to is much older than 8 years. Dates
back to the last century. But wasted spark has been used long before that.
And it's not much used today on car engines.

I think its wuite ofetn used because...
It's beauty was it only
required a crank signal. Full sequential requires a camshaft one too. As
electronics have come down in price, most now use one coil per cylinder
and a combined trigger from crank and cam.

...it avoids the cam trigger.. In teh end its a matter of cost and
packaging. If you can do way with a cam sensor you save space and
money. AND there is almost NO downside to firing the plug in the middle
of the exhaust stroke on a 4 cylinder. I suspect it gets more
complicated at 6 cylinders+ tho.

In article
,
thirty-six wrote:
Like I said the distributor was never the problem but the points and the
capacitor were.

The Ducellier moving contact points removed any problem inherent in
the system, that of contact point erosion. Filing the points was
redundant,
Only a bodger filed points. Replacement was the correct way.

all that was required at service was to run a slip of brown
paper over the contacts, check the dwell angle with a simple meter and
check the ignition timing hadn't drifted from it's previous setting.

Wear on the heel of the cam? All mechanical devices wear out. But using a
simple transistor removed the high current that cause points erosion. Of
course not long after electronic triggers became practical removing points
once and for all - luckily.

Capacitor faults were usually imagined, many ignition circuit problems
were due to badly made connections in the vehicle wiring. Just like
the charging circuit, it needs someone with a bit of nouse about
electrickery, else you'll be changing plugs and points every month of
the year.

You've still not addressed the impossibility of making a mechanical
advance system that was in any way accurate - even when new, let alone in
service.


Breakerless ignition and electronic advance and retard were huge
improvements. Getting rid of the distributor is purely cost saving. At
some point the cost of the mechanics of a distributor and the weight
were less than the cost of multi-coil multi-transistor setups.

But its no big deal performance wise.

How little you know.

The Rover/Motorola MEMS (forgot which version) was one such device
which did take advantage of gains in engine "tuning" as it did have a
significant range of learning to modify the ingnition mapping. A
larger throttle plate and a higher pressure fuel rail alongside light
modification to the HT cables and plugs and some simple "ratcheting"
at the manifold/port junctions would have the vehichles wheelspinning
all through second gear if one stamped on the pedal in the dry with
standard tyres at any speed. between 8mph and 60mph. Less
modification than this gave the 214Si a 60 to 100mph time of about 4
seconds. These are not the capable speeds of factory new machines,
but the capabilities of slight attention to detail not possible in a
normal production environment. There were reports that the multipoint
injection 1.4 K16 was procucing torque figures at between 40 to 50%
over the factory official release on the standard Engine management
Unit, significantly larger than the 1.6 factory variant.

All that says is the standard 1.4 had remarkably poor engine management.
Peak torque is largely a function of the engine size, and can be achieved
using carburettors. As can maximum BHP. Full engine management comes into
its own for reliability, consistency and better efficiency, ie fuel
consumption. I never understood why BL farted around with all their
various poor injection systems when they could just have bought Bosch and
be done with it.

--
*Save the whale - I'll have it for my supper*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
I never understood why BL farted around with all their
various poor injection systems when they could just have bought Bosch and
be done with it.


Not Invented Here. Gotta be Lucas...

yeah the bosch was the first injected system I had - Opel Manta 2l. Just
bloody WORKED.

In article ,
The Natural Philosopher wrote:

..it avoids the cam trigger.. In teh end its a matter of cost and
packaging. If you can do way with a cam sensor you save space and
money. AND there is almost NO downside to firing the plug in the middle
of the exhaust stroke on a 4 cylinder. I suspect it gets more
complicated at 6 cylinders+ tho.

Ford used EDIS on 4,6 and 8 cylinder engines. Maybe even more, for all I
know. It might be a problem on an engine with an odd number of cylinders,
though. ;-)

--
*Some days you're the dog, some days the hydrant.

Dave Plowman London SW
To e-mail, change noise into sound.

In article , The Natural Philosopher
wrote:
Dave Plowman (News) wrote:
I never understood why BL farted around with all their various poor
injection systems when they could just have bought Bosch and be done
with it.


Not Invented Here. Gotta be Lucas...


My SD1 was the first production car from BL with electronic fuel
injection. And only the ECU was Lucas - everything else, injectors, AFM
TPS, EAV sensors etc Bosch.

yeah the bosch was the first injected system I had - Opel Manta 2l. Just
bloody WORKED.

--
*Sometimes I wake up grumpy; Other times I let him sleep.

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 26 Jan 2012 08:45:36 -0800 (PST), thirty-six
wrote:

The Rover/Motorola MEMS (forgot which version) was one such device
which did take advantage of gains in engine "tuning" as it did have a
significant range of learning to modify the ingnition mapping. A
larger throttle plate and a higher pressure fuel rail alongside light
modification to the HT cables and plugs and some simple "ratcheting"
at the manifold/port junctions would have the vehichles wheelspinning
all through second gear if one stamped on the pedal in the dry with
standard tyres at any speed. between 8mph and 60mph. Less
modification than this gave the 214Si a 60 to 100mph time of about 4
seconds.

Hell I knew I shouldn't have ****ed away 35k on a Lotus Exige a decade
or so ago. 780kg, 177bhp, 226 bhp / tonne and it's getting 'blown
away' by mildly tuned low grade repmobile from a decade earlier.

0-60 4.7 seconds
0-100 12.3 seconds
60-100 7.6 seconds

Not even close to 4 seconds

But is that a one off? Lets look at a Porsche 911 (997 GT2 from
2007)

3.6 litre twin turbocharged 523bhp top speed 200+ mph
Power to weight ratio 363 bhp / tonne

0-60 3.3 seconds
0-100 7.4 seconds
60-100 4.1 seconds

Oooh close, but still apparently blown away by your tuned Rover

But that is German, so what about a Caterham 7 from blighty, say a CSR
260 weighing all of 575kg with 260bhp on tap, roller throttles, dry
sumped, 410bhp per tonne.

0-60 3.6 seconds
0-100 8.9 seconds
60-100 5.3 seconds

Another fail, blame the barn door aerodynamics.

So in desperation at finding something to beat your rover, how about
the Nissan Skyline GT-R from 2010, traction control, launch control,
478bhp, 434lb.ft at 3200 rpm, 276 bhp / tonne

0-60 3.8 seconds
0-100 8.5 seconds
60-100 4.7 seconds

Oh **** another failure. Tojo will no doubt fall on his sword.


The only conclusion? Expect a raid from the drugs squad because
that is some very serious crack you are smoking.

P.S. Why didn't you run the vehicle at Le Mans, was it the wheelspin
in 2nd gear at 60mph that ruined your chances?



--

On Thu, 26 Jan 2012 17:28:37 +0000, Dave Plowman (News) wrote:
In article
,
thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require
a reversed coil connection.

.... although it triggered a memory and prompted me to check the wikipedia
entry for the Alfa twin-spark engines, which claims:

"As both plugs are connected to the same coil the spark one of them
operates with reversed polarity and requires decreased breakdown voltage"

(http://en.wikipedia.org/wiki/Alfa_Ro...n_Spark_engine)

.... of course, it's Wikipedia, which doesn't make it right

cheers

Jules

On Jan 26, 11:13 am, "Dave Plowman (News)"
wrote:
In article ,
Tim Downie wrote:

thirty-six wrote:
The 1.3 maestro was capable of 55mpg with
outstanding acceleration for its size. 3rd gear acceleration from
20mph to 80mph in under 8 seconds, through 1st and 2nd I was able to
out-accelerate an XR2 I doubt that would be possible with wasted
spark ignition.
Makes you wonder why they bothered with the 2L turbo version then.
20-80 in third gear time 14.6
(http://www.maestroturbo.org.uk/performance.php)
A 1.3 doing it in "under 8 seconds" seems a tad unlikely to me.

I'm not even sure a 1.3 would do 80 in third.

well nearly


"Speed range (max speed on gears, top gear value theor.): (km/h/mph)

I: 47 / 29

II:83 / 52

III 125 / 78"

Jim K

On 26/01/2012 11:07, Dave Plowman (News) wrote:

It's a 60 mph increase. The zero to 60 through the gears on a 1.3 Maestro
won't be anything close to 8 seconds. More like 12 or so. And no car ever
built will have a better 20-80 mph speed in a single gear.

I'd say more than 12 - that was the 1.6. 14 or 15?

While I thought the Maestro was an underrated car, and quite liked mine
apart from the requirement for leaded fuel and the rust, they're nothing
like 36/Trevor describes.

On Jan 26, 5:41*pm, "Dave Plowman (News)"
wrote:
In article
,
* *thirty-six wrote:

Like I said the distributor was never the problem but the points and the
capacitor were.
The Ducellier moving contact points removed any problem inherent in
the system, that of contact point erosion. *Filing the points was
redundant,

Only a bodger filed points. Replacement was the correct way.

all that was required at service was to run a slip of brown
paper over the contacts, check the dwell angle with a simple meter and
check the ignition timing hadn't drifted from it's previous setting.

Wear on the heel of the cam? All mechanical devices wear out. But using a
simple transistor removed the high current that cause points erosion. Of
course not long after electronic triggers became practical removing points
once and for all - luckily.

Capacitor faults were usually imagined, many ignition circuit problems
were due to badly made connections in the vehicle wiring. *Just like
the charging circuit, it needs someone with a bit of nouse about
electrickery, else you'll be changing plugs and points every month of
the year.

You've still not addressed the impossibility of making a mechanical
advance system that was in any way accurate - even when new, let alone in
service.



Breakerless ignition and electronic advance and retard were huge
improvements. Getting rid of the distributor is purely cost saving. At
some point the cost of the mechanics of a distributor and the weight
were less than the cost of multi-coil multi-transistor setups.

But its no big deal performance wise.

How little you know.

The Rover/Motorola MEMS (forgot which version) was one such device
which did take advantage of gains in engine "tuning" as it did have a
significant range of learning to modify the ingnition mapping. * A
larger throttle plate and a higher pressure fuel rail alongside light
modification to the HT cables and plugs and some simple "ratcheting"
at the manifold/port junctions would have the vehichles wheelspinning
all through second gear if one stamped on the pedal in the dry with
standard tyres at any speed. between 8mph and 60mph. * Less
modification than this gave the 214Si a 60 to 100mph time of about 4
seconds. *These are not the capable speeds of factory new machines,
but the capabilities of slight attention to detail not possible in a
normal production environment. *There were reports that the multipoint
injection 1.4 K16 was procucing torque figures at between 40 to 50%
over the factory official release on the standard Engine management
Unit, significantly larger than the 1.6 factory variant.

All that says is the standard 1.4 had remarkably poor engine management.

The torque gains were simply made with the original MEMS without
modification to it.

Peak torque is largely a function of the engine size, and can be achieved
using carburettors. As can maximum BHP. Full engine management comes into
its own for reliability, consistency and better efficiency, ie fuel

The only problem found was with a sticky idle air control valve which
made restarts at -10degC next to impossible. I pulled the coolant
temperature sensor for the clever box to get the engine to start and
had erratic running until the engine temperature was truly up at which
time I replaced the connector and was able to continue driving on
frozen roads.
After cleaning the valve and resetting it and the throttle position
sensor, it all ran fine. The 'air' through that valve is from the
valve cover and although there are oil separaters, carbon is pulled
through the IACV. Resetting the system is essential for the box to
do all the clever bits and keep the engine running smoothly and
powerfully throughout the range. Economy for this is based on how
heavy is your right foot. Use it half way and less, which is still
quick, and 50mpg+ is a certainty. The vehicle is not used
sufficiently to make accurate mpg checks, but it wouldn't surprise me
if I could get 60mpg from it by taking full advantage of the fuel
control system by keeping rpm above 1750 and below 3000 except when
accelerating or actually stopping.

consumption. I never understood why BL farted around with all their
various poor injection systems when they could just have bought Bosch and
be done with it.

Maybe because they didn't want to pay the licence fee for every single
installation with the forcast production and that they wanted a system
which could be used across the whole range of vehicles including Land
Rover and Leyland light freight. Actually I thought they did use a
Bosch system in Freight Rover, Range Rover and the Landy FC with the
Buick V8. I remember the police Leyland vans were very fast, probably
as quick as the pursuit cars that they could actually keep the wheels
on the road. IIRC Merseyside and Cheshire police shared 6 RS200's and
four of them were scrap within two weeks. It was ridiculous to expect
the officers who had barely seen a race-track to control thos monsters
on public roads.

On Jan 26, 6:42*pm, The Other Mike
wrote:
On Thu, 26 Jan 2012 08:45:36 -0800 (PST), thirty-six

wrote:
The Rover/Motorola MEMS (forgot which version) was one such device
which did take advantage of gains in engine "tuning" as it did have a
significant range of learning to modify the ingnition mapping. * A
larger throttle plate and a higher pressure fuel rail alongside light
modification to the HT cables and plugs and some simple "ratcheting"
at the manifold/port junctions would have the vehichles wheelspinning
all through second gear if one stamped on the pedal in the dry with
standard tyres at any speed. between 8mph and 60mph. * Less
modification than this gave the 214Si a 60 to 100mph time of about 4
seconds.

Hell I knew I shouldn't have ****ed away 35k on a Lotus Exige a decade
or so ago. *780kg, 177bhp, 226 bhp / tonne and it's getting 'blown
away' by mildly tuned low grade repmobile from a decade earlier.

It was a Lotus I chased who had passed me at somewher about 85-90mph
and I pulled out at 60mph before flooring it. It was quite nice
having that engine pull hard in third gear all the way to 100 at which
point I was holding speed with the sports car. Apparently much had
been going on at the time (lmid to late90s) to use the ram effect to
pressurise the air intake and although I've not looked at it in detail
it is possible it works correctly on this model once the air intake is
correctly aligned.

0-60 4.7 seconds
0-100 12.3 seconds
60-100 7.6 seconds

Not even close to 4 seconds *

But is that a one off? * *Lets look at a Porsche 911 (997 GT2 from
2007)

3.6 litre twin turbocharged 523bhp *top speed 200+ mph
Power to weight ratio 363 bhp / tonne

0-60 3.3 seconds
0-100 *7.4 seconds
60-100 4.1 seconds

Oooh close, but still apparently blown away by your tuned Rover

It's only mildly touched, the fully pegged engines require the stiffer
suspension of the 2000Y on models.

But that is German, so what about a Caterham 7 from blighty, say a CSR
260 weighing all of 575kg with 260bhp on tap, roller throttles, dry
sumped, 410bhp per tonne.

0-60 3.6 seconds
0-100 8.9 seconds
60-100 5.3 seconds

Another fail, blame the barn door aerodynamics.

So in desperation at finding something to beat your rover, how about
the Nissan Skyline GT-R from 2010, traction control, launch control,
478bhp, 434lb.ft at 3200 rpm, 276 bhp / tonne

0-60 3.8 seconds
0-100 8.5 seconds
60-100 4.7 seconds

Oh **** another failure. *Tojo will no doubt fall on his sword.

The only conclusion? * * Expect a raid from the drugs squad because
that is some very serious crack you are smoking.

Nah, I got the ignition system working like on a racing engine. It is
possible to make greater gains on the track or road than that expected
by what's shown on the dyno. Most engines fail to reach their
potential torque delivery on the road through poorly adopted spark
systems.

P.S. *Why didn't you run the vehicle at Le Mans, was it the wheelspin
in 2nd gear at 60mph that ruined your chances?

Crap driving seat, needs new headlamps and the back is too cramped for
a picnic. The car is not really suitable for driving in excess of
100mph for long periods AFAIK as there does seem to be an element of
driver fatigue setting in at over 90mph which could be due to loose
struts at the back (I might check it out someday). Rover did speed
trials with the k16 engine in a new metro body and had the needle
pinned at around 130mph for 24 hours IIRC but with four drivers. I
suspect that a MKII coupe of the 200, a Tomcat was entered in Monte
Carlo, but I'm not sure there was the recognition of the value of the
K outside of Rover at that time so it more likely the Rover coupe
would be fitted with a bigger Honda engine or older and bigger Rover
engine.

"Dave Plowman (News)" wrote in message
...
In article
,
thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require a
reversed coil connection.

I thought many modern systems used AC anyway.

On Jan 26, 11:07*am, "Dave Plowman (News)"
wrote:
In article ,
* *The Other Mike wrote:

The 1.3 maestro was capable of 55mpg with
outstanding acceleration for its size. *3rd gear acceleration from
20mph to 80mph in under 8 seconds,
Given that a Lotus Elise Sport 135, a car with a 1.8 K series, with a
combustion chamber and port arrangement not too dissimilar to Keith
Duckworths classic DFV, a car not known to be underpowered or crippled
by poor choice of gear ratios, with a kerb weight of 725kg, takes 10.7
seconds to cover 20-80 in 3rd gear, one has to assume that your
Maestro, weighing 875kg, had somehow entered another dimension, an
entire new field of vehicle *performance where basic physics is
forgotten and the impossible happens when a bull defecates in a nearby
field.

Of course the A Series was renown for decent torque, unlike the K Series
which is more of a screamer. But not that good.
It's a 60 mph increase. The zero to 60 through the gears on a 1.3 Maestro
won't be anything close to 8 seconds. More like 12 or so. And no car ever
built will have a better 20-80 mph speed in a single gear.

In its rough and ready condition, no, but with careful attention to
detail it was possible to get 2nd gear to pass 60mph on the regular
components. Doing a 0-60 was incredibly difficult because of the fine
control needed to get the appropriate slip for maximum take-off speed
and tyres must be prepared for this. I wasn't going to that trouble
for public road use and it only hs a diddy clutch plate, a hot
restart, which is what we want could easily fracture such a small
item. And so I used simple 3rd gear acceleration as the basis of my
testing to get the fuelling and ignition timing spot-on. Once it
dipped below 8 seconds there was a firmness of connection between the
pedal and engine so that confidence was present at all times during
overtakes.

My guess is there's a 1 missing off the 8. Making 18 seconds. The factory
claimed 50-70 in 4th gear took 11.6 seconds.

No chance, the NSL section of road I used barely had enough lenght as
it was and the test required starting in a bend so I didn't end up
flying down a 30mph street. Coming back was more risky as it meant I
was exceeding the limit at the approack to a junction with the bend
ahead. There was a few times I had to drop the stopwatch as someone
emerged ,despite adequate sightlines, and I needed to brake hard.
Road testing is not stricly legal and I always feared getting nabbed,
but Maestros didn't attract attention with a good centre box.

On Jan 26, 8:08*pm, Clive George wrote:
On 26/01/2012 11:07, Dave Plowman (News) wrote:

It's a 60 mph increase. The zero to 60 through the gears on a 1.3 Maestro
won't be anything close to 8 seconds. More like 12 or so. And no car ever
built will have a better 20-80 mph speed in a single gear.

I'd say more than 12 - that was the 1.6. 14 or 15?

While I thought the Maestro was an underrated car, and quite liked mine
apart from the requirement for leaded fuel and the rust, they're nothing
like 36/Trevor describes.

Did you run yours with 5W30 synthetic engine oil at standard
temperature (sealing ALL the coolant leaks with 40% glycol), 75w
gearbox oil, degum the rings, use straight plugs with cutback
electrodes running undergapped, levelled the needle in the carb with
the piston face and burred out the ports and manifolds? I may have
missed something, oh yes the fuel, I used Total from a local garage
and added some upper cylinder lubricant (1/2 what they said was
enough). And I found a proper light oil for the piston damper in the
carb. Used a colourtune, set the spark advance for maximim
acceleration with the vacuum unit plugged, went back and set the jet
accurately for maximum acceleration and finally went back on another
day to fine tune the ignition. 20-80mph was my standard test and
getting off the last second was only possible when running with upper
cylinder lubricant, but I doubt this would be noticable with gummed
rings and a weeping cooling system as was typical.

On Jan 26, 11:02*am, "Tim Downie" wrote:
thirty-six wrote:
*The 1.3 maestro was capable of 55mpg with
outstanding acceleration for its size. *3rd gear acceleration from
20mph to 80mph in under 8 seconds, through 1st and 2nd I was able to
out-accelerate an XR2 * I doubt that would be possible with wasted
spark ignition.

Makes *you wonder why they bothered with the 2L turbo version then.

20-80 in third gear time 14.6
(http://www.maestroturbo.org.uk/performance.php)

Again they are published times, the real times on an engine which has
been correctly run in by hard acceleration and decelleration through
the revs performed much better than an engine leaving the factory.


A 1.3 doing it in "under 8 seconds" seems a tad unlikely to me.

Magrinally under 8 seconds, the MG properally ran in was scaringly
quick and tempting to drive like that.

On Jan 26, 11:13*am, "Dave Plowman (News)"
wrote:
In article ,
* *Tim Downie wrote:

thirty-six wrote:
*The 1.3 maestro was capable of 55mpg with
outstanding acceleration for its size. *3rd gear acceleration from
20mph to 80mph in under 8 seconds, through 1st and 2nd I was able to
out-accelerate an XR2 * I doubt that would be possible with wasted
spark ignition.
Makes *you wonder why they bothered with the 2L turbo version then.
20-80 in third gear time 14.6
(http://www.maestroturbo.org.uk/performance.php)
A 1.3 doing it in "under 8 seconds" seems a tad unlikely to me.

I'm not even sure a 1.3 would do 80 in third.

But I'm guessing it should have read 18 rather than 8. And I can
understand the reluctance to change gear, being a Maestro.

I managed to get 33 in first with the tappets rattling, 62 in second
and somewhere between 85 and 89 in third. There was no point in
pushing the engine further without stiffer valve springs and I didn't
fancy the bother that may have led to.

On Jan 26, 10:04*pm, "dennis@home"
wrote:
"Dave Plowman (News)" wrote in ...

In article
,
* thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. *As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require a
reversed coil connection.

I thought many modern systems used AC anyway.

That would explain the get-around and the necessity for resistive
plugs. There were systems that were plasma burners and had to be
regulated so the plug electrodes would last the race.

In article ,
Clive George wrote:
It's a 60 mph increase. The zero to 60 through the gears on a 1.3
Maestro won't be anything close to 8 seconds. More like 12 or so. And
no car ever built will have a better 20-80 mph speed in a single gear.

I'd say more than 12 - that was the 1.6. 14 or 15?

I've got the BL brochure from '85 for my SD1, and that includes the
Maestro.

1.3 1.6 2.0EFI
0-60 12.0 10.5 8.5

While I thought the Maestro was an underrated car, and quite liked mine
apart from the requirement for leaded fuel and the rust, they're nothing
like 36/Trevor describes.

--
*I just got lost in thought. It was unfamiliar territory*

Dave Plowman London SW
To e-mail, change noise into sound.

dennis@home wrote:


"Dave Plowman (News)" wrote in message
...
In article
,
thirty-six wrote:
sure, but why does a wasted spark reverse the polarity on the coils?
you mist have no understanding of electricity to say that.

That was the design of the systems I studied at BTEC level 4. As far
as understand it is inherent in the wasted spark system,

Could you go back to your case notes, or point at the textbooks it used?

I can't think of any reason why wasted spark should ever (have) require a
reversed coil connection.

I thought many modern systems used AC anyway.



I believe some do.

In article
,
thirty-six wrote:
I'm not even sure a 1.3 would do 80 in third.

But I'm guessing it should have read 18 rather than 8. And I can
understand the reluctance to change gear, being a Maestro.

I managed to get 33 in first with the tappets rattling, 62 in second
and somewhere between 85 and 89 in third. There was no point in
pushing the engine further without stiffer valve springs and I didn't
fancy the bother that may have led to.

This was from the speedo?

--
*Learn from your parents' mistakes - use birth control

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 26 Jan 2012 14:21:43 -0800 (PST), thirty-six
wrote:

On Jan 26, 11:07*am, "Dave Plowman (News)"
wrote:


My guess is there's a 1 missing off the 8. Making 18 seconds.

No chance.

Exactly.

If you were to get a time even approaching 8 seconds then you'd need
to weigh less than a jockey... and it would be just you, strapped to
the powertrain. That totals 200kg. 100kg for the engine, and another
50kg for gearbox, driveshafts, wheels and a platform for a grade one
arse weighing 50kg strapped to the powertrain producing about 70bhp.

Now try it with a vehicle weighing around 875kg, with a 50kg driver.
300bhp, might just about do it. Or about 230bhp / litre.

As a reference point the very best small bore 1000cc Mini 7 racing
engines, with 12G940 "1.3" heads and the MG Metro camshaft profile are
producing around 90bhp at the flywheel, at around 8500rpm, with a
knife edged crank that realistically lasts just a few hundred miles.
They breath through a single choke of a 40DCOE weber with mixture and
timing optimised for one purpose only, racing. So that is 90bhp per
litre.

Furthermore, the 3.5 litre engine that won the F1 world championship
in 1994, with pneumatic valvegear, 4 valves per cylinder, and revving
to 13000rpm only has around 700bhp - or 200bhp / litre.

I now have to leave the room as the smell of bull**** coming from your
posts is overpowering.


--

In article ,
Jules Richardson wrote:

... although it triggered a memory and prompted me to check the
wikipedia entry for the Alfa twin-spark engines, which claims:

"As both plugs are connected to the same coil the spark one of them
operates with reversed polarity and requires decreased breakdown voltage"

Interesting. With EDIS, they are connected to the same 'coil' in as much
it has just the one feed to it. But the two plug outputs aren't simply in
parallel - there is a reading of 12K ohms between them, so I'd guess the
coil has twin secondaries. Since it is likely an auto transformer, I
suppose it could look like the outputs are in anti-phase. But the spark
isn't a simple DC arc anyway, and I've never heard of one of the plugs
from a pair wearing faster than the other, and it hasn't happened here
even when using the original plugs designed for conventional ignition.

I'll see if I can find a schematic of the EDIS coil.

--
*Half the people in the world are below average.

Dave Plowman London SW
To e-mail, change noise into sound.

On Jan 26, 11:32*pm, "Dave Plowman (News)"
wrote:
In article
,
* *thirty-six wrote:

I'm not even sure a 1.3 would do 80 in third.

But I'm guessing it should have read 18 rather than 8. And I can
understand the reluctance to change gear, being a Maestro.
I managed to get 33 in first with the tappets rattling, 62 in second
and somewhere between 85 and 89 in third. *There was no point in
pushing the engine further without stiffer valve springs and I didn't
fancy the bother that may have led to.

This was from the speedo?


Yes, from a speedo which was over-reading by probably between 5 and
8% I'm not the only one to use that as a reference, the 20 to 80 time
gains are still significant despite the error. The error was
certainly minimised by using as much tyre pressure as was safe and I
doubt the error was in excess of 4%.

On Jan 26, 11:26*pm, "Dave Plowman (News)"
wrote:
In article ,
* *Clive George wrote:

It's a 60 mph increase. The zero to 60 through the gears on a 1.3
Maestro won't be anything close to 8 seconds. More like 12 or so. And
no car ever built will have a better 20-80 mph speed in a single gear..
I'd say more than 12 - that was the 1.6. 14 or 15?

I've got the BL brochure from '85 for my SD1, and that includes the
Maestro.

* * * 1.3 * *1.6 * 2.0EFI
0-60 *12.0 * 10.5 * 8.5

While I thought the Maestro was an underrated car, and quite liked mine
apart from the requirement for leaded fuel and the rust, they're nothing
like 36/Trevor describes.


In practice the from the showroom times were more like 10.5 to 11
seconds for 0-60 as tyres with lower rolling resistance were fitted
after the tests were made.

On Jan 26, 11:45*pm, "Dave Plowman (News)"
wrote:
In article ,
* *Jules Richardson wrote:

... although it triggered a memory and prompted me to check the
wikipedia entry for the Alfa twin-spark engines, which claims:
"As both plugs are connected to the same coil the spark one of them
operates with reversed polarity and requires decreased breakdown voltage"

Interesting.
Isn't it?
With EDIS, they are connected to the same 'coil' in as much
it has just the one feed to it. But the two plug outputs aren't simply in
parallel - there is a reading of 12K ohms between them, so I'd guess the
coil has twin secondaries. Since it is likely an auto transformer, I
suppose it could look like the outputs are in anti-phase. *But the spark
isn't a simple DC arc anyway, and I've never heard of one of the plugs
from a pair wearing faster than the other, and it hasn't happened here
even when using the original plugs designed for conventional ignition.

That's because the dissipated energy is smaller so the effect isn't
noticable by looking at the plugs, hence they "last forever". The
smaller energy dissipation is noticable in how fast the flame front
develops, the hotter and fatter the spark the faster the flame moves
and the greater the available torque. I suppose one could use a lower
energy output when torque demands are lower and at lower speed this
may be beneficial in assisting a quiet running engine for creeping
about town under the cover of darkness.

I'll see if I can find a schematic of the EDIS coil.

Just pulse it with a button cell and check for direction of needle
deflection.

On 26/01/2012 23:26, Dave Plowman (News) wrote:
In articleW_idnRAeZfRbL7zSnZ2dnUVZ8qCdnZ2d@brightvie w.co.uk,
Clive wrote:
It's a 60 mph increase. The zero to 60 through the gears on a 1.3
Maestro won't be anything close to 8 seconds. More like 12 or so. And
no car ever built will have a better 20-80 mph speed in a single gear.

I'd say more than 12 - that was the 1.6. 14 or 15?

I've got the BL brochure from '85 for my SD1, and that includes the
Maestro.

1.3 1.6 2.0EFI
0-60 12.0 10.5 8.5

Ooh, slightly suprised, but thanks for that. Nippier than their
reputation then.

I'm beginning to wonder if 36 has been looking at the kph scale...

On 27/01/2012 00:22, thirty-six wrote:
On Jan 26, 11:26 pm, "Dave Plowman
wrote:
In articleW_idnRAeZfRbL7zSnZ2dnUVZ8qCdn...@brightvie w.co.uk,
Clive wrote:

It's a 60 mph increase. The zero to 60 through the gears on a 1.3
Maestro won't be anything close to 8 seconds. More like 12 or so. And
no car ever built will have a better 20-80 mph speed in a single gear.
I'd say more than 12 - that was the 1.6. 14 or 15?

I've got the BL brochure from '85 for my SD1, and that includes the
Maestro.

1.3 1.6 2.0EFI
0-60 12.0 10.5 8.5

While I thought the Maestro was an underrated car, and quite liked mine
apart from the requirement for leaded fuel and the rust, they're nothing
like 36/Trevor describes.


In practice the from the showroom times were more like 10.5 to 11
seconds for 0-60 as tyres with lower rolling resistance were fitted
after the tests were made.

That's the first time I've heard somebody claim the manufacturer's 0-60
times were pessimistic.

On Jan 27, 12:42*am, Clive George wrote:
On 26/01/2012 23:26, Dave Plowman (News) wrote:

In articleW_idnRAeZfRbL7zSnZ2dnUVZ8qCdn...@brightvie w.co.uk,
* * Clive *wrote:
It's a 60 mph increase. The zero to 60 through the gears on a 1.3
Maestro won't be anything close to 8 seconds. More like 12 or so. And
no car ever built will have a better 20-80 mph speed in a single gear..

I'd say more than 12 - that was the 1.6. 14 or 15?

I've got the BL brochure from '85 for my SD1, and that includes the
Maestro.

* * * *1.3 * *1.6 * 2.0EFI
0-60 *12.0 * 10.5 * 8.5

Ooh, slightly suprised, but thanks for that. Nippier than their
reputation then.

I'm beginning to wonder if 36 has been looking at the kph scale...

Ha ha, I think I'd notice if the valves were bouncing at 33kph. Oh
yes, the optimal tappet clearance was around 11 or 12 thous, not 14 as
stated. That was a seriously good cam and every one I've met who kept
a Maestro for some years has done so with finding this performance
tweak. And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.

The Other Mike wrote:
On Thu, 26 Jan 2012 14:21:43 -0800 (PST), thirty-six
wrote:

On Jan 26, 11:07 am, "Dave Plowman (News)"
wrote:

My guess is there's a 1 missing off the 8. Making 18 seconds.
No chance.

Exactly.

If you were to get a time even approaching 8 seconds then you'd need
to weigh less than a jockey... and it would be just you, strapped to
the powertrain. That totals 200kg. 100kg for the engine, and another
50kg for gearbox, driveshafts, wheels and a platform for a grade one
arse weighing 50kg strapped to the powertrain producing about 70bhp.

Now try it with a vehicle weighing around 875kg, with a 50kg driver.
300bhp, might just about do it. Or about 230bhp / litre.

As a reference point the very best small bore 1000cc Mini 7 racing
engines, with 12G940 "1.3" heads and the MG Metro camshaft profile are
producing around 90bhp at the flywheel, at around 8500rpm, with a
knife edged crank that realistically lasts just a few hundred miles.
They breath through a single choke of a 40DCOE weber with mixture and
timing optimised for one purpose only, racing. So that is 90bhp per
litre.

Furthermore, the 3.5 litre engine that won the F1 world championship
in 1994, with pneumatic valvegear, 4 valves per cylinder, and revving
to 13000rpm only has around 700bhp - or 200bhp / litre.

I now have to leave the room as the smell of bull**** coming from your
posts is overpowering.



Well I think we had all figured that one out. Its Drivel, with cars, not
combis.

On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six
wrote:

And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.

Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.

On Jan 27, 10:00*pm, wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six

wrote:
And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. *After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. *I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.

Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.

The same techniques are used on every other model on the racetrack.
For a normally-aspirated small capacity engine with siamesed ports on
a single choke, yes it was probably the finest. Never saw a Ford
Fiesta with the same arangement anywhere near it.

On 27/01/2012 22:42, thirty-six wrote:
On Jan 27, 10:00 pm, wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six

wrote:
And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.

Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.

The same techniques are used on every other model on the racetrack.
For a normally-aspirated small capacity engine with siamesed ports on
a single choke, yes it was probably the finest. Never saw a Ford
Fiesta with the same arangement anywhere near it.

Ach, where's Dave Baker when you need him.

On Jan 27, 10:50*pm, Clive George wrote:
On 27/01/2012 22:42, thirty-six wrote:









On Jan 27, 10:00 pm, wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six

*wrote:
And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. *After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. *I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.

Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.

The same techniques are used on every other model on the racetrack.
For a normally-aspirated small capacity engine with siamesed ports on
a single choke, yes it was probably the finest. *Never saw a Ford
Fiesta with the same arangement anywhere near it.

Ach, where's Dave Baker when you need him.

Nice one, just reading his notes and came across a point about tyre
pressure and how it affects dyno readings and road performance.
Well, BL specced the tyre pressure at 28 all around and I had the
fronts at around 36psi. That possibly gives 10% more torque at the
wheels in third gear. he also states that manufacring tolerances will
typically have engines producing 5% more or less than manufacturers
spec.

In article
,
thirty-six wrote:
Nice one, just reading his notes and came across a point about tyre
pressure and how it affects dyno readings and road performance.
Well, BL specced the tyre pressure at 28 all around and I had the
fronts at around 36psi. That possibly gives 10% more torque at the
wheels in third gear. he also states that manufacring tolerances will
typically have engines producing 5% more or less than manufacturers
spec.

But the results you're claiming ain't minor improvements like the odd 5%.

Also, you can be damn sure BL didn't use vehicles down on power etc to
produce their performance figures.

--
*Sorry, I don't date outside my species.

Dave Plowman London SW
To e-mail, change noise into sound.

thirty-six wrote:
On Jan 27, 10:50 pm, Clive George wrote:
On 27/01/2012 22:42, thirty-six wrote:









On Jan 27, 10:00 pm, wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six
wrote:
And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.
Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.
The same techniques are used on every other model on the racetrack.
For a normally-aspirated small capacity engine with siamesed ports on
a single choke, yes it was probably the finest. Never saw a Ford
Fiesta with the same arangement anywhere near it.
Ach, where's Dave Baker when you need him.

Nice one, just reading his notes and came across a point about tyre
pressure and how it affects dyno readings and road performance.
Well, BL specced the tyre pressure at 28 all around and I had the
fronts at around 36psi. That possibly gives 10% more torque at the
wheels in third gear.

er no, it does not.

The torque is entirely a function of engine torque times overall gear
reduction ratio.

Tyre pressures affect many things, but not torque at the wheels.

Do you realise what a fool you are making of yourself?


he also states that manufacring tolerances will
typically have engines producing 5% more or less than manufacturers
spec.

Considerably more than that with a 'blueprinted' engine. Well they
CLAIMED it was only 'blue printed' ..as long as the scrutineers didn't
spot the bored out to the max oversized pistons fitted skimmed to the
min head that ran on 110 octane fuel ONLY.....and the carefully smoothed
ports with the edge of spec large valves and the scrubbed clean air
intakes...an the dymamically balanced crank and matched pistons that
would redline a whole 750rpm beyond the normal and the delicately
corroded and reskimmed flywheel ..and the slightly 'adjusted' camshaft
with the absolutely to the micron adjusted valves and teh somewhat
stiffer springs that fell off the back of..well we never did know where
they came from.

Let say that one in a billion engines might *just* accidentally have
come off the production line like that...

On Fri, 27 Jan 2012 22:00:18 +0000, grimly4 wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six
wrote:

And a check with oil pressure after filling with the 30weight synthetic
as even then the oil pressure can be high and needs reducing to spec to
develop full acceleration. After sorting "everything out" I found that
the baffle plates in the sump to be inadequate for my road use as I was
developing high G on open corners. I never did fit a horizontal plate
to prevent a dry pump, it was a good reminder how hard I should be
cornering.

Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon of
the race track.

All the ones I knew of that were owned by friends went mouldy.

On Jan 27, 11:53*pm, "Dave Plowman (News)"
wrote:
In article
,
* *thirty-six wrote:

Nice one, just reading his notes and came across a point about tyre
pressure and how it affects dyno readings and road performance.
Well, BL specced the tyre pressure at 28 all around and I had the
fronts at around 36psi. *That possibly gives 10% more torque at the
wheels in third gear. *he also states that manufacring tolerances will
typically have engines producing 5% more or less than manufacturers
spec.

But the results you're claiming ain't minor improvements like the odd 5%.

Also, you can be damn sure BL didn't use vehicles down on power etc to
produce their performance figures.


The vehicles they used were on regular oil at least a grade thicker in
both the gearbox(which was overfilled) and the engine. The vehicles
they used would not have had the rings bedded in well after a
significant wear-in period. The vehicles they used, if fully to spec
would have had engine oil in the carb piston damper which did restrict
breathing. The vehicles they used if to spec would have had the tyres
under pressure (and of a higher rolling resistance, economy tyres were
later fitted between brochure publication and actual manufacture). The
tappet clearance on a specification vehicle is too big. the spark
plugs on a spec vehicle would not have been non-resistive, small
gapped and cut back. The specification that they were legally obliged
to follow within manufacturing error still would always result in a
slower vehicle. These were base model vehicles expected to attract a
minimum insurance premium. They would have lost sales based on
expected insurance premiums if they had released a specification
resulting in a quicker vehicle. 68bhp IIRC was sufficient at that
time in an 850kg car meant principally for around town and tight back
lanes outside town. Using the greater capacity I had extracted at the
wheels was rarely fully possible in these environments. The ignition
mods I made allowed the timing to be 4 deg later to produce maximum
aaccelleration IIRC. Every change I made outside specification made
an on the road timeable improvement in acceleration. The use of upper
cylinder lubricant was also not to specification, it was a NO-NO
according to BL. Just because I wasn't throwing money at the cylinder
head (there was nothing wrong with it except the constraint of the
siamese port to valve timings) and fitting aftermarket carbs (BL got
it right with the SU), blah blah blah, doesnt mean that significant
gains over a specification vehicle cannot be made with what on the
surface, to the uneducated, are insignificant procedures. Every
change resulted in timed improvements, they all added up. Adding
10.bhp to specification without any modification was normal, taking to
85.bhp was considered rare. I don't know the bhp figures, I felt it a
waste of money making such a test, the vehicle complied fully to the
insurance policy as it was not modified (meaning a signifant variation
in the powertrain or chassis components) and the acceleration
optimisation was what mattered to me.

On Jan 28, 1:40*am, The Natural Philosopher
wrote:
thirty-six wrote:
On Jan 27, 10:50 pm, Clive George wrote:
On 27/01/2012 22:42, thirty-six wrote:

On Jan 27, 10:00 pm, wrote:
On Thu, 26 Jan 2012 19:30:06 -0800 (PST), thirty-six
*wrote:
And a check with oil pressure after filling with the 30weight
synthetic as even then the oil pressure can be high and needs reducing
to spec to develop full acceleration. *After sorting "everything out"
I found that the baffle plates in the sump to be inadequate for my
road use as I was developing high G on open corners. *I never did fit
a horizontal plate to prevent a dry pump, it was a good reminder how
hard I should be cornering.
Amazing.
Who'd have thought it. The humble Messtro, a giant killer and a demon
of the race track.
The same techniques are used on every other model on the racetrack.
For a normally-aspirated small capacity engine with siamesed ports on
a single choke, yes it was probably the finest. *Never saw a Ford
Fiesta with the same arangement anywhere near it.
Ach, where's Dave Baker when you need him.

Nice one, just reading his notes and came across a point about tyre
pressure and how it affects dyno readings and road performance.
Well, BL specced the tyre pressure at 28 all around and I had the
fronts at around 36psi. *That possibly gives 10% more torque at the
wheels in third gear.

er no, it does not.

The torque is entirely a function of engine torque times overall gear
reduction ratio.

Stop splittin hairs, you know what I mean. The under pressured
specification tyre gives a greater rolling resistance, particularly so
when unworn. The lower pressured tyres absorb more energy so slowing
the acceleration of the vehicle.

Tyre pressures affect many things, but not torque at the wheels.

Do you realise what a fool you are making of yourself?

he also states that manufacring tolerances will

typically have engines producing 5% more or less than manufacturers
spec.

Considerably more than that with a 'blueprinted' engine. Well they
CLAIMED it was only 'blue printed' ..as long as the scrutineers didn't
spot the bored out to the max oversized pistons fitted skimmed to the

Never touched.
min head that ran on 110 octane fuel ONLY.....and the carefully smoothed

Fuel was carefully selected but was only 4star never mixed.

ports with the edge of spec large valves
The standard valves were already maximised for that design that had
already been established.

and the scrubbed clean air
intakes...

Air intake was standard.

an the dymamically balanced crank

Not touched, BL had already done an excellent job, that engine whirred
like a sewing-machine for most of the time, only after about 3/4 revs
with WOT could it sound invasive.

and matched pistons that

It seemed BL managed that.
would redline a whole 750rpm beyond the normal and the delicately
corroded and reskimmed flywheel ..

It was so smooth it could have managed with a lightened flywheel.

and the slightly 'adjusted' camshaft
Sprockets were untouched, only a new chain was fitted after a small
problem which may have affected chain lubrication.

with the absolutely to the micron adjusted valves and teh somewhat
stiffer springs that fell off the back of..well we never did know where
they came from.

No, the standard springs were bouncing at the maximum speeds.

Let say that one in a billion engines might *just* accidentally have
come off the production line like that...

My intention was to make some actual real identiiable changes such as
re-porting the head and modifying the combustion area but as I
researched the subject I found that BL had already made the changes
that "engine tuners" had been striving for, for the previous 12 years
or so. It also emerged that the limitations on timing were close to
optimal for a road engine and making it any "hotter" would always
result in rough running across the rev range due to the siamesed
porting. The single choke carb was all that was required and an
appropriate size was applied, the SU being very versatile in being
able to accurately deliver the correct fuel ratio whatever the
manifold depression.