If a 305 is essentally a bigger 350 with just bigger pistons and different insides, but an identical block, can a 305 be bored over to be a 350 or maybe the 383 that I want. I heard from my father who is a mechanic that its the same engine except for the insides. I really want a 383 to replace my LG4 but if i could bore it that would be great. He isnt sure if its possible so I was just wondering if anyone knows about it.

 

The 305 is 3.736" bore, the 350 (and 327) is 4.000" bore. Both are cast such that they have about the same cylinder wall thickness. A safe overbore on either is about .060", so if you add 3.736" and .060", you get 3.796" - meaning if you try to bore a 305 block to 4.000" bore, you'll be about 0.102" short on wall thickness (remember, bore is diameter, so only half comes from each "side" of the cylinder).

If you want a 383, you need a 4" bore block casting. You can put a 3.75" stroke crank in a 305 block, but that is never cost-effective (comes out to 334 cubic inches with a .030" clean-up overbore), being smaller and more expensive than a rebuilt 350.

 

I had a friend that said he sleeved his 305 to make it a 350. I had a really hard time believing that, especially because like five7 mentioned you could just buy a 350 at the expense of that much work. I suppose that it's possible, just don't know why you'd bother.

 

Your friend is pulling your chain. The only way to get 350 cubes from a 305 is to have a .60 over bore and a 3.875 crank. I have never heard anybody doing that and I don't even know if they could. It would be the biggest waste of money.Almost all 3.875 cranks are expensive because most are forged.