i have a 90 chevy i bought the motor for my truck it has all the goodies 30 over with 10 to 1 flat top piston's but the crank has 20 thou bearings on the rods and the crank bearings are pretty rough so i was thinking of changing the crank what does any think....i'm not sure if a 305 tpi crank is the same as 350 tpi...........any sugestions would realy help me out thanks

The 350 and the 305 historically have shared stroke and bearing size. The machine shops say a 20 thou will work fine, but I have never tried it. If it won't clean at 10 I replace. You can probably get by if the mains will clean by 20 but I wouldn't unless money was a MAJOR factor, or you intend to sell it quick. I would put the 305 crank in and double check all tollerences. don't forget to wash the metal out of the engine! other wise all that metal that is gone from the mains will be right back eating everything! also make sure of the new parts you put in!!!! I was really pissed when a made in china timeing gear that had been reboxed as USA ate my brand new 350 at 15,000!

You can use a .020 crank in a performance Chevy engine with no issues. Even a .030 crank isn't that big a deal. We grind to .020 all the time. But with the low cost of brand new Scat or Eagle replacement cranks, it's almost not worth grinding.

I wouldn't use a 305 crank in a 350 unless you have a very light piston. Look at a 305 crank, and you will notice it has a lot more material removed from it for balancing. The 305 crank is quite a bit lighter then a 350, and this can cause a balance issue and possible vibration.