Motor Swap/Install sorry its long winded.

[joedoozer]

Harmonic balancer from a late Gen 305 to Gen 1 block 350........ Here is how it all started.

I bought my 72 LWB about a year ago. It had a newer (center bolt valve cover) 305 in it, and a 700R4 tranny. The original 350 was in the back on an old tire, complete from pan to carb. I decided to rebuild the 350.......8 months later and I am ready to bolt her in.

I got the the 305 out, and on the ground and I start pulling parts and swapping things. Sending units and fittings and what not. I notice the balancer is shorter and fatter than the one off the 350. It had a triple pulley on the crank, and the inside groove is for the alt, and the outside was the power steering pump (non-a/c). Obviously if I try and bolt the pulleys to the taller thinner balancer they won't line up with the alt or the pump.

Here is what I know of balancers. All SBC (except 400's i think) are internally balanced, so the balancer isn't there to "balance" the engine. If it were, you wouldn't be able to buy them from a catalog. It is in place to absorb harmonic vibrations that occur in the engine at certain RPM's. I know this is extremely important on racecars (short track and drag cars). The engines are screaming, and running in the upper end of the RPM range most of its life.

For a daily driver/cruiser it will never have the abuse a drag engine or a circle track car will get, or run over 4000 for lengthy periods of time. Can I use that balancer off the 305 for the 350? It fits the crank, it is the correct depth for the crank bolt, and the correct diameter for the front seal. I also have an add-on timing plate, so I can use different size balancers. Or should I start walking the junk yards for the correct pulleys for the crank (to get the correct spacing)? And yes I know the correct thing to do is buy a new balancer......but I am trying to avoid that. And if it does have any kind of a shake, I will fork out the money for a new balancer. I don't want to fatigue the crank at all.

Both balancers are in excellent shape. The rubber is in perfect shape, no dry-rot or cracks. So I would like to use one of them.

Sorry this dragged on, I kept going back and writing more stuff.