<VV> #4 misfire, exhaust 'spit'
kovacsmj at sbcglobal.net
Sat Jul 8 17:43:46 EDT 2006
Mike, the 'spit' is in the exhaust not in the head. Instead of a satisfying rumble like the right side, there is a noise that sounds like escaping gas but it smells rich, which goes along with the low CHT and the fact that removing the spark plug wire from #4 while it is running eliminates the spit and the rpm drops just a tad. Removing any other spark plug wire reduces the RMP much more.
The left exhaust is cooler than the right, the left door does not open up all the way despite a functioning thermostat. All this adds up to #4 is not firing to get the job done. Changing plugs / wires brought NO change in the sound, cap is new, not cracked and spotless.
As suggested, I'll check the lift on the cam for that cylinder, but for sure the valve was moving when I did the hot valve adjustment. I'll also figure out how to do a leak down check. It is about time I used this diagnostic method. Also will carefully check the vacuum.
I'll not pursue this further till after the national when I have the patience to pull the left head off and probably the #4 piston. I'll take the '69 convertible!
I'm convinced that there is a problem with the #4 and it probably is not the head gasket.
Thanks to all for the advice, I'll also work with some local Corvair people with experience.
Mike Ioanes <mioanes at woh.rr.com> wrote:
. Oh yeah, the #4 spark plug did not appear like it was firing (others are a
bit sooty, this one is too clean) when I pulled it. Compression is 150 +.
I would suspect a head gasket more if the compression was lower. Aleaking
head gasket does make a noticeable and distinctive "spit"...don't ask me how
I know this, but it's the same reason I know that the right head will come
off a 64 without taking the engine out of the car.
spent a little time under the back of my 64
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