OK got a 502 early bowty block chevy 7/16 rods 2 PC rear main seal crank,don't know par t number,regular 502 pistions,a motor I got. It did not come with flywheel so I put a 454 wheel o n it have a vibration at 3000. Should it have a 502 flywheel,905 part number? I'm aware of 50 2 cranks and the difference between 454 cranks I'm trying to do this without tearing motor apart to rebalanced. Has an y body ever tested unbalance with a vibration tester? I see them on e bay wonder if they work,it's a pain to r+r motor to change wheels to see If I t vibrate s I can r u. On test stand easier. Thanks

Do you have any idea who built the engine originally ? Can you look at the harmonic damper and see if it is external or internal balance ? As far as I know the 2pc seal 454 and 502 flywheels are the same. Exactly which 454 flywheel did you use ? Was it for a 2 pc seal engine or 1 pc seal ?

Just to be certain, you do have a dowel pin in the crank to properly position the flywheel ? Also does the vibration get worse above 3000 rpm ?

you probably need an externally 502 balanced flywheel . you probably have a neutral balanced flywheel on there now .

If the one he has now is a 454 flywheel it is not neutral but there is definitely a difference between the 454 1 pc seal and 2 pc seal ones.

thought there was a different one from cast to forged crank, or did I imagine that?

Correct but I think that is on the 1 pc seal cranks. Its a pretty small difference but it is there.

not as senile as I sometimes think I am. thought there was something about that but could not remember exactly. thanks

I have a 454 balancer on crank has dowel pin its a 456 fl y wheel at 3000 it's bad guy who built motor is in heavn I might try 502 905 wheel it's hard to detect vibration I on ground running it

454 and 502 flywheels are the same for the 2 pc crank. I am not sure what you are calling a 905 flywheel or a 456 one ? What do they fit. Do you have the entire part number ?

Those r last 3 numbers of flywheel I got 2 502s late model w 1 PC rear main one was a 525 other a Sci 700 had 905. On them maybe I'll try one but don't want to put in boat just to try it that's why I was asking if there is a way to detect vibration