[azkeebler]

Okay, this question normally has a obvious answer, but this is the first car ever I've had deiseling issues with that I couldn't easily remedy.....

Had the 194 rebuilt in the wife's car. Found the machine shop installed flat-top pistons instead of the dish that were stock in the lower compression 79Y motor. I can only assume they reground the cam for the lower compression specs as no specs were given to me.

We have an issue of occasional deiseling when we shut off the engine after a short to moderate drive(6-12 miles). Have tried various octane available here at normal pump, timing and dwell is dead on, and idle is at norm. Researching the manuals i notice the same distributor number I have, vacuum advance, head, plugs are the same with lower and higher compression fours with an exception of a lower maximum advance on the higher compression, possibly due to stronger mechanical weight springs?

Yes, the conditions are higher outside temperatures in the high 90's that don't help the situation, but hoping any others that run street driven higher compression engines have advice to help the isssue at hand.

I do have a four barrel intake and an edelbrock /carter i can install if there is thought of too lean issue exists with the one-barrel. car runs great otherwise and show no serious heating issues otherwise. Just unsure of how to hook up the tv cable correctly to the edelbrock correctly without binding or having incorrect ratio as the car is powerglide equipped.

[John in Minnesota]

Calif. gas.!!!??? Play with the timimg. You know move it 1 degree or so. Drive it. See what happens. Then do it again. It's got to be in the timing. May lost power. Or you could buy avgas. John

[c5farmer]

Does the car "ping" when you accelerate? If so, the higher compression combined with low octane gas is the problem. If the dieseling is only happening when you shut it off, the problem, according to a GM diagnosis and repair manual, can be corrected by the following steps:
1. Check the following for sticking: carb linkage, choke and linkage, throttle linkage, fast idle cam. The butterflys need to close to idle specs.
2.Disconnect and plug vacuum advance hose from distributor. Hook up dwell meter and timing light, run engine and check timing & dwell.
3.If equipped with a fast idle solenoid, run engine at idle and disconnect solenoid wire. There should be a drop in the rpm. If not replace solenoid.
4. If condition still exists, suggest to owner to try a different gasoline!

That"s the diagnosis procedure from my GM manual. Hope it helps

[mechanickeith]

If the compression is too high, you can use a low comp head from 63. All 63's had flat top pistons & used 2 different heads to adjust compression. If an automatic car, I leave it in gear when I shut it off. manual trans, let the clutch out with trans in gear when shutting off.

[azkeebler]

thank you all for the thoughts.

I'm down to the conclusion where I need to get it to idle better. No pinging at throttle, very smooth acceleration and no desiling if not idling in traffic before switching it off.

Found a set of rebuilt '63 heads (543797), but are the same cc chambers as my current head.

The car shakes pretty bad if idle is any smidgin below the idle it is at now. So either have a small vacuum leak, or valvetrain variance I need to find. I suspect the valvetrain some as I had converted to oiling rockers setup and unsure of the length of the hollow pushrods that came with the motor are compatible.

Of course, the machine shop gave everything a thumbs up, but are the same ones that didn't know how to modify the front cover for the newer crank seal. Shoulda known.

Was hoping to join in on a Rallye to Norwalk with Keith, but between this car giving fits, and work issuing mandatory 6-day/10-12hour a day overtime currently, just can't get away. GRRRRR!!!