So a friend of mine picked u a 425 that used to be in a boat. He wants to to in place of his 350 in his 73 cutlass. Can all the late model brackets and pullies be used if some kind of spacer was used on the harmonic balancer to shim out the pulley? It wouldn't put the engine out of balance in any way would it? Thanks, in advance

 

All of the '73 350 pulleys and brackets should bolt on and work just fine, but be sure to use ALL of them, so that everything fits and works.

- Eric

 

Make sure that the water pump is the same length as the one on 350, everything should line up then.

 

I know the balancer is narrower on the 425 can you shim out the crank shaft pulley so its where it needs to be so everything lines up? He can't use anthing beside the 425 balancer can he? Maybe I'm wrong but I thought on the 330/425 and 350/455 one was internally balanced and one other was externally balance? I hope my question makes sense.

 

Forgot about the water pump.

Yes, change that with everything else.


As for the balancer, as far as I know, they're all the same dimensions flange to flange.
Someone else will be able to confirm that for you, or you can just measure them yourself, since you've got both.

- Eric

 

This is correct. Only the outer ring is different. The hubs are all the same length..

 

And, the pulley mounting surface ends up located in the same place, regardless of the balancer used.

NO GOOD can come from putting a shim or spacer behind the main driving pulley. The crank pulley is indexed [located concentric to the crank] by residing on [around] the balancer's slight protruding ring. The bolts cannot be depended on to situate the pulley concentric to the crankshaft. Any sort of spacer or shim over about oh 1/16" thick would cause the pulley to lose contact with the hub's centering ring.

That little bit of spacing can be accommodated by the rubbery belt.