I've got a complete 305 and a bare 350 block. What I'm wondering is can I put the 305 crank in the 350 or will I have balancing problems? I'd use the 305 flexplate and balancer. Could I lighten 350 pistons to work with this crank? Any thoughts or ideas. It would just be a street motor nothing high rpm. I'd also get one of those cheap $150 rebuild kits with cast pistons.

The 305 and 350 use the same 3.48 stroke crank. Its the same crank! The only differance in the two motors is the bore. You will need 4.00" (350) pistons. everything else will work fine.

Bungy,
The 305 crank is balanced differently due to the fact that the stock 305 pistons are a lot lighter than the 350 ones. You cannot take that much weight off the 350 pistons.

Depending on what year 305 crank it is, if you get a kit with some of the newer hypereutectic pistons, it might be ok. The newer 350 pistons are a lot lightere than the old ones. I know of guys that have swaped them and not had a vibration problem, but I also know of at least one that did it and had to hear the dreaded " I told you so " :(

Thanx, I pretty much knew they were weighted different but I was hoping maybe the weight was close enough that I could use it. Again thanx for the info. By the way the 305 is a 1980.

If you look at the counter weight on the crank it is drilled for balance. I believe on a 305 the hole is drilled a lot deeper. The crank could be balanced to use in a 350 but it would probably be cheaper to use a 350 crank.

Bungy,
Do you have the pistons that came out of the 305 ? If so, get someone that does balancing to weigh them and see if you can find a 350 piston that is close. For a street engine, if you can get within 10 grams you will probably never know the difference.