327 serious problem

[Verne_Frantz]

I can ask for a pic of the plugs. He said the vibration starts at about 1200rpm and gets worst up to about 35-40mph. He can feel it in the seat and it's bad. He said all the normal suspects have been checked, ie: tire balance, driveshaft, pulleys. The mechanic said he checked the crank and its good.
Right now my question is what caused the appearance on the piston?? The mechanic says the problem is the gas and the carb and that's why he was referred to me. But I disagree that a carb problem would cause a vibration. Maybe a miss or hesitation, but not an actual vibration.
I'll be speaking with him later for more info.


Verne


He just sent this pic of a plug. They all look like this and they look fine to me.

[Bruce]

Could it be the harmonic balancer has spun on the rubber ?
I had this problem years ago on a L-S6, unbelievable vibration.
Bruce

[firstgenaddict]

Catastrophic Engine destroying detonation can be heard from the roadside when occurring on a passing vehicle.

WOW those valves look overheated.
Piston looks like cooked on oil -
a flat top in a 250 hp 327 hard to believe there were detonation.

[RALLY]

Originally Posted by Bruce

Could it be the harmonic balancer has spun on the rubber ?
I had this problem years ago on a L-S6, unbelievable vibration.
Bruce

I mentioned this too. Harmonic balancer could be bad. Never heard of a bad vibration caused by timing. I am sure the timing was set correct when starting engine and then make sure it was correct before driving the car. Same goes with the carb. To me if he got 100 miles on the engine without the bad vibration, then all of the sudden it started and can feel it when sitting in the seat, it could be a drive train issue. Before i would of ever torn the engine back down i would of done some real research on the problems i mentioned. Driveshaft out of balance? bad u-joints? loose flywheel, flex-plate? This is not a hi-perf engine here. Have the crank checked again. Out of balance? Check harmonic balancer. Check complete drive train. Dont over look anything. Its could be an obvious thing. Let us know.

[jdv69z]

Originally Posted by Verne_Frantz

I can ask for a pic of the plugs. He said the vibration starts at about 1200rpm and gets worst up to about 35-40mph. He can feel it in the seat and it's bad. He said all the normal suspects have been checked, ie: tire balance, driveshaft, pulleys. The mechanic said he checked the crank and its good.
Right now my question is what caused the appearance on the piston?? The mechanic says the problem is the gas and the carb and that's why he was referred to me. But I disagree that a carb problem would cause a vibration. Maybe a miss or hesitation, but not an actual vibration.
I'll be speaking with him later for more info.


Verne


He just sent this pic of a plug. They all look like this and they look fine to me.
Attachment 181322

Agree. I was thinking detonation due to an extreme lean condition, but the plugs show otherwise.