"oldjag" wrote in message Some metal content,
(barely)...This started last spring actually when
I helped a driver in an '69 olds 442 convertable that died
on the
roadside. Towed the car to my home garage a block away.
Found very
weak spark and traced problem to a made in China, Blue
Steak brand
distributor cap that was molded in such a way that the cap
pushed on
the breaker points, (actually Blue Streak quality was also
bad years
ago before they were made in China). The distributor
bearings were
also in dire shape so the dist was replaced. It started
and ran well
now, but idled poorly. I checked the air/fuel ratio with
a Innovate
wide ratio afr meter and it was lean at idle, about 15-16
afr, and far
too lean for an old car at idle.
The owner had another Quadrajet carb., actually the one
that came on
the car, so I rebuilt it, installed a new fuel filter and
reinstalled
the carb. Other than the usual stripped inlet filter
thread, the carb
looked in good shape. On startup the air fuel was now
okay, around
13:1 at idle, and the idle quality was better but still
almost
sounding like a miss when listening at the the tailpipes.
I checked
for air leaks, brake booster booster, PCV etc. Ran a
propane check to
look for leaks around the manifold, compression was 200
psi. on six
cylinders and 180-190 on two others. Idle vacuum was
kinda low at 14
inches, at the intial timing of 8 degrees. Everything
else looked
okay. The car ran great except at idle, ie it pulled
really well at
WOT, chirped the tires when the automatic hit second gear
etc., and
lots of torque, but still a lousy idle. The owner was
satisfied for a
while, but in the fall decided a engine rebuild was in
order. The
engine had 250K plus miles. He asked me if I wanted to do
it, but I d
too many irons in the fire. So he took it to a decent
local garage
where they yanked the engine for a total rebuild. Two
valves appeared
to have been leaking, so intially this was thought
probable cause for
the poor idle. Well, here is where it gets weird.
It went off too the machine shop, got hot tanked, got a
rebore
0.030" over, stock compression pistons, a 5 angle valve
job, new
valve, and valve springs, lifters, cam and main bearings,
reground
crank, fuel pump, oil pump, roller timing chain and gears,
a new Pro
Comp "mild cam" and a new non points type HEI distributor
and wires.
Now get this...it still does not idle right, in fact it's
worse and
power is down a quite a bit also. So the garage tries two
other
(used) stock Quadrjet and two Holley carbs, still no dice.
The cam
timing and ignition timing are checked and rechecked.
Compression is
now 220 psi on all eight.
The CompCam is pulled, and an Edlebrock Performer Plus Cam
installed.
This is a pretty mild cam, almost stock duration, slightly
more lift.
Idle is still crap and vac. won't go over 12 inches unless
the timing
is advanced way up. Next the garage pulls the stock
intake manifold
and puts on a Edlebrock Performer Plus aluminum intake.
No real
change. (A hairline crack was noticed between the
secondary bores of
the stock iron intake, but this does not cause an external
air leak
and would not effect idle in any case). The exhaust is
then dropped
and idle quality does not improve, ie still poor idle vac.
The torque
converter is unbolted from the flexplate, idle is still
bad, vac.
comes up slightly. Belts are pulled from the fan so no
accessories are
running, still no change.

Now the garage wants more money to go further and the
owner is livid.
I told the owner to get to an agreement with the shop on
who owes what
and bring the car over to let me look at it.
My feeling at this point is that the engine is probably
healthy from a
mechanical standpoint, but that the existing Quadrajet
Carb.may simply
need to be properly set up for the new cam.

The plan now is to put the stock intake back on and sell
the Edlebrock
manifold, as the owner wants a stock looking motor. I
don't think the
hairline crack between the secondary bores on the iron
stock intake
matters one iota. On many manifolds this area is open
anyway. I
could TIG it up, but I guessing this would be a waste of
time. None
of the carbs tried may have been jetted right for this
engine. Any
Quadrajet/Olds experts out there care to weigh in?

It looks like you have already tried all the things that
have been suggested
by the guys responding except for one: The crankshaft
vibration damper.
The outer ring must have rotated slightly giving you late
ignition timing.
My vote goes with those that said that that was the
problem......phil