305/350 crank
 

Got a street 305 Chevy im rebuilding.It had a bad crank,so I came across a 350 crank which is the same stroke.Can I use the 350 crank ,or will it have a balance problem?Dont really want to spend the money to balance it. thanks

Re: 305/350 crank
 

Lyn,
The 350 and 305 cranks that I have done have been quite a bit different in balance. If you are replacing pistons it seems like they are making even the stock replacement pistons a lot lighter so that will make the problem even worse.

I would say it would be worth having it at least checked. You probably don't have to do the entire balance job, making all of the rods and pistons the same weight etc. Just use one of the 305 assemblies as a reference to make the bobweight.

Hope this helps,

Re: 305/350 crank
 

I cant say for sure what a 350 crank in a 305 will do. But I know for a fact that a 305 crank in a 350 will vibrate at around 2500-3000 RPM. Bad enough that you will take it back apart.

Re: 305/350 crank
 

The 305 crank with 350 rod-piston is a problem. The 350 crank with a 305 rod-piston is not a problem. No balancing required for a stock piston or cast replacement. The 305 crank is the nastiest piece of junk that is associated with Small Blocks IMHO.

Re: 305/350 crank
 

Dont forget the 262 and 267 ci motors as candidate for piece of junk award

Re: 305/350 crank
 

305-350 cast cranks were the same casting number and the only difference was the factory balancing. If I recall correct the casting number was 448...last 3 and if you look at the depth of the holes on cranks from a 305 vs a 350 you wll see a big difference in hole depth....the 305 bobweight was lighter so the crank had deeper balance holes drilled.

You could use either crank in either engine but needed to address the balance issue......

There is no difference in the counterweight overall diameter that I can ever recall....

Re: 305/350 crank
 

Steve,
Other than the balancing there is absolutely no difference between the two crankshafts.

I just looked through some old balance cards and found a 305. The piston and pin was about 60 grams lighter than most of the stock type 350's I have done. 622 grams compared to 682 for the 350 If that is not enough to make you believe that the 350 crank needs to be rebalanced to use in a 305, then I don't know what is :)

Re: 305/350 crank
 

267,305,350 all are same crank, EXCEPT for balance,you can identify them by comparing counterweights,267 will have deepest holes,305 a little less, some 267/305 cranks have notches cut in counterweights to remove weight.

I would at least try to find 305 crank, or balance the 350 crank,I balance everything,be surprised how good a 3.5 briggs will cut grass when balanced,took 2- 3/4X3/4 pieces of heavy metal.
Might get someone to balance w/bobweight made up from 1 piston/rod.

Mike Taylor 3601

Re: 305/350 crank
 

Some of the rebuilder manufacturers make 305 pistons that are purposefully heavy for use with a 350 crank in a 305 block.

Re: 305/350 crank
 

I have balanced a few cranks for other shops and the F/M 345 pistons are now appox.72 grams lighter then the older ones.