Anybody here have any experience with hoppin' up the engines ? I've been
asked to mill .045" of one from and OHV motor , don't know the brand . One
thing O found after I clamped it to the mill table , the area over by the
pushrod area is about .005 down from the area around the piston . No obvious
difference in the appearance of the original milling looks like about a 10
or 12 inch face mill on the surface .
If this guy likes my work , there are 4 or 5 more who want the same thing
done . I guess you could call this redneck racin' in it's most basic form .

--
Snag

On Mon, 5 Aug 2013 23:10:47 -0500, "Terry Coombs"
wrote:

Anybody here have any experience with hoppin' up the engines ? I've been
asked to mill .045" of one from and OHV motor , don't know the brand . One
thing O found after I clamped it to the mill table , the area over by the
pushrod area is about .005 down from the area around the piston . No obvious
difference in the appearance of the original milling looks like about a 10
or 12 inch face mill on the surface .
If this guy likes my work , there are 4 or 5 more who want the same thing
done . I guess you could call this redneck racin' in it's most basic form .

Get the guy to being in a used head gasket. You'll be able to tell
what is bearing on what from that.
--
Cheers,

John B.

On Tuesday, August 6, 2013 12:10:47 AM UTC-4, Terry Coombs wrote:
Anybody here have any experience with hoppin' up the engines ? I've been

asked to mill .045" of one from and OHV motor , don't know the brand . One

thing O found after I clamped it to the mill table , the area over by the

pushrod area is about .005 down from the area around the piston .
Snag


How flat was it before clamping the head down? I have no experience on small aircooled engines, but have worked on a couple of car engine heads that were blowing gaskets. Did these with a big file and a carpenters square to check for flatness. As I remember the heads were out of being flat by about 0.030. I probably got them flat to within .005 and they did not blow any more gaskets.

Dan

wrote in message
...
On Tuesday, August 6, 2013 12:10:47 AM UTC-4, Terry Coombs wrote:
Anybody here have any experience with hoppin' up the engines ? I've been

asked to mill .045" of one from and OHV motor , don't know the brand . One

thing O found after I clamped it to the mill table , the area over by the

pushrod area is about .005 down from the area around the piston .
Snag


How flat was it before clamping the head down? I have no experience on
small aircooled engines, but have worked on a couple of car engine heads
that were blowing gaskets. Did these with a big file and a carpenters
square to check for flatness. As I remember the heads were out of being
flat by about 0.030. I probably got them flat to within .005 and they did
not blow any more gaskets.

Dan

The head is pretty flat , max difference is right at .005 , and there's a
pretty good impression around several of the bolt holes - I don't think this
head distorted at all when I clamped it , it's like 4" thick . I was mostly
checking to see if the valve vcover sealing surface is parallel with the
bottom surface last night . It was pretty dern close - checked with just
enough force to keep it from sliding and the same measurements after firmly
clamped . I was wondering if the slight difference was designed in to
cantilever the clamping force over towards the piston area .
--
Snag

On Tuesday, August 6, 2013 12:10:47 AM UTC-4, Terry Coombs wrote:
Anybody here have any experience with hoppin' up the engines ? I've been

asked to mill .045" of one from and OHV motor , don't know the brand . One

thing O found after I clamped it to the mill table , the area over by the

pushrod area is about .005 down from the area around the piston . No obvious

difference in the appearance of the original milling looks like about a 10

or 12 inch face mill on the surface .

If this guy likes my work , there are 4 or 5 more who want the same thing

done . I guess you could call this redneck racin' in it's most basic form .



--

Snag

A loooong time ago we'd mill the heads on Continental (single-cylinder/four cycle) engines for quarter-midget race cars.

A Burke #4 horizontal mill did a fine job of it. In fact, I've still got that mill now almost 50 years later.

Clamped through the spark plug hole for some reason that I no longer recall.

That, and we'd make thin head gaskets from copper sheet.

Another trick was to make offset woodruff keys for the flywheel.
Changes (we advanced) the timing with magneto ignition.

Yet another cheat was to trick the cam profile with a fast & high intake pop up.

Of course, all of the above was NOT legal for the class we raced in.
But a challenge teardown was always possible if we got too fast.

Good times, hadn't thought about it for quite awhile.
We had a ball, hope you do too.

--
PaulS