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I found a 1980 chevy that originally came with a 350 v-8 and a th350 trannie. Now it has a 454 from a '76 with the same 350. It has a terrible shaking problem! IT does not smoke or knock! The motor mounts and trannie mounts are new. The complete bottom end has been gone through and it still shakes. Crank,bearings,timing gears and chains! The trannie has also been rebuilt! I am starting too thing the previous owner did not switch the flywheels. what do ya'll think? Motor is tight but just shakes a lot!!!
 

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IMO if the starter turns the motor over fine with the coil wire pulled, the flywheel is not the problem.

What else on the conversion did the previous owner swap, or not swap over. How are the pulleys running, and what type of engine balancer does it have.

Given that the motor runs properly? these are places to start looking.

Scott
 

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external balancing

I stopped at oreilly autoparts yesterday after work. I pulled a small block flywheel for a th350 to a 350v-8 and a flywheel for a th350 to a 454v-8 they both look too have the same diameter and bolt pattern. Leading up too a easy mix up. BUT!!! The one for the 454 had a huge weight tack welded to it and the one for the small block did not have this. So i am thinking that the person you did the swap just used the small block flywheel and that is why it is shaking. ?????????? The man who owns it now did not do the swap he bought it from the fellow who did this.
 

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Most (But not all) small blocks are internaly ballanced and do not require the weight. Big blocks need that weight to offset the rotating mass of the crank shaft or it will shake.:)
 

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spasch said:
Most (But not all) small blocks are internaly ballanced and do not require the weight. Big blocks need that weight to offset the rotating mass of the crank shaft or it will shake.:)
Not all big blocks are externally balanced, but the 454 is so if they used the 350 flywheel on the 454 then that would be a problem.
 
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