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Help! Misfiring

Boggie

Member
Joined
Jan 7, 2014
Messages
9
Location
Orange Park FL
Corvette
1981, Silver & Black, red/blk factory hood decal
I have 81' stock (Bowlin' Green), 56,000. Had carb rebuilt because revs wee 2K idle. Within a few days, idle went from 800 to 400, shake, rattle, roll. I'm told cly#8 valve is toast. As a owner with lo technical savvy, I'm trying to build up confidence with local expert. Since I'm looking at head retooled and valve replaced, what else should I throw $$ at while engine is apart? Last year it was 8grand.
 
How many miles did you put on that carb rebuild in that week? I can't imagine you could burn a valve in that short time if it was running smooth but too fast before the rebuild. Have you checked to see if the choke is opening when it warms up? Is it smoking or does it have a real rich exhaust smell (burns your eyes) when it runs rough? Are all of the plug wires on tight?

It sounds like you have a new carb problem and your problem before the rebuild could have been a simple vacuum leak or maybe the fast idle cam sticking or a bad choke pull off diaphragm. Before you let anyone tear into your engine do a compression check and post the numbers for each cylinder back here.

Tom
 
misfire

Thanks for your quick reply. Probably less than 50, no 20 miles. It had been surging ion park and neutral for that matter. Go back a bit-car sat for two years, the story of which I replay in my mind on Halloween Eve. I took the vehicle to a guy who rebuilt '67 and another Camaro, etc. Had them replace battery drain/flush fluids, new tires, new fuel pump, and a bunch of other stuff unrelated to engine. Noticed that engine was surging in park and neutral (2000-2500rpm). So had high Idle solenoid replaced. Stopped surging and idle was high 2000rpm, dropping to 900 in drive. Horrible clunk in gear though. Told replace/rebuild carb was solution. Replaced radiator, all water hoses, all vacuum hoses, rebuilt carb professionally, Intake manifold/gasket, higher thermostat, water pump, spark plugs, wires, ignition set. Drove awhile and while in garage, noticed that before turning off idle had dropped to 400rpm, choke light on, shaking and stop. Hard to restart. Had to go out of town for a week. Started up and battery DEAD. Jumped and took to shop. Diagnosis was misfire #*. Eventually told that they had smoke coming out of that exhaust valve/cylinder, etc. etc. There was strong smoke smell during the early process, but...I always noticed that choke started and would release with pressing pedal. they said that they did compression, but I didn't ask for numbers. They said only to replace defective vales, +gasket, machine head, etc. So th ere's the brief. What should I do now that we are waiting for the heads to come back?
 
Thanks for your quick reply. Probably less than 50, no 20 miles. It had been surging ion park and neutral for that matter. Go back a bit-car sat for two years, the story of which I replay in my mind on Halloween Eve. I took the vehicle to a guy who rebuilt '67 and another Camaro, etc. Had them replace battery drain/flush fluids, new tires, new fuel pump, and a bunch of other stuff unrelated to engine. Noticed that engine was surging in park and neutral (2000-2500rpm). So had high Idle solenoid replaced. Stopped surging and idle was high 2000rpm, dropping to 900 in drive. Horrible clunk in gear though. Told replace/rebuild carb was solution. Replaced radiator, all water hoses, all vacuum hoses, rebuilt carb professionally, Intake manifold/gasket, higher thermostat, water pump, spark plugs, wires, ignition set. Drove awhile and while in garage, noticed that before turning off idle had dropped to 400rpm, choke light on, shaking and stop. Hard to restart. Had to go out of town for a week. Started up and battery DEAD. Jumped and took to shop. Diagnosis was misfire #*. Eventually told that they had smoke coming out of that exhaust valve/cylinder, etc. etc. There was strong smoke smell during the early process, but...I always noticed that choke started and would release with pressing pedal. they said that they did compression, but I didn't ask for numbers. They said only to replace defective vales, +gasket, machine head, etc. So th ere's the brief. What should I do now that we are waiting for the heads to come back?


There is nothing for you to do now but wait if you already have the engine torn down. Only the tech working on your vehicle can advise you on how to proceed, he is the one who diagnosed it and took it apart and has done a visual on the cylinder head and cylinder walls. Hopefully you have a skilled and trustworthy technician.
 

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