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Discussion Starter #1
Why am I having engine vibration. On RPRm excellation. I ask Moron to Balance dont know if he did.

1986 C4 L98 About 10:1 compression
 

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5.7 I assume. One piece rear main or two piece? Did he replace the harmonic balancer? Is it automatic? Did he change flywheels? More info would be nice.

Toby
 

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Yes, give us more information. Was the flex plate replaced by any chance? It may have gotten a weighted flex plate for a 305" put on it. Or a 305" damper. Tell us the whole story and maybe we can help you. Was it your engine that got rebuilt or did you get another engine rebuilt? You might just have 2 plug wires crossed (very likely). Or one cylinder that is missing (also very likely).
 

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Discussion Starter #5 (Edited)
Flywheel was Reground. Harmonic balancer was new before rebuild. Just pulled it off to double check. Install a used Richmond 6 speed and Mcleod 75222 clucth/bearing. 5.7 Bored .30 over big cam. Crank was switch out to a reground. And he supposedly balanced it. I hoping I had a down cylinder. Plug wire was a little Lose on # 6 cylinder. Plug looked ok. I ask engine builder he said. Rare on the Balance to be issue. Hope he right. One piece.

Questions were cranks the same Length for 350. Is there a difference in crank for one piece or two piece up front. Harmonic balancer went on crank. But crank didnt seem to go even 3/4 into Balancer. Long bolt and void? Look like it was push in up to Cam Sprocket. How you know when to stop with balancer?
 

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How close to the timing cover is the harmonic balancer? If the builder got an older crank, the early w/2 piece rear main, I don't think the flywheel would bolt up but I could be wrong but if it did the balance would be off. But if the builder bal. the engine, the crank & flywheel should have been done together & should have been caught during the balance procedure. The only other thing to look at would be the clutch assy. Did they dyno the engine?

Toby
 
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