My dad and I are having a disagreement... What are the differences between the 305 block and a 350 block?? What makes a motoe a 350? Is the entire block bigger? Are the pistons bigger? Does that alone make the diff? He thinks you can make a 305 a 350 by boring the cylinders out and putting in bigger ones. Doesn't this just make it bored "30 over"? not an actual 350? The reason for this debate, I am swapping a 305 for a 350 in my Camaro, and most of the stuff bolts right up. The intake manifold didn't due to a year discrepency. The stock 305 had a flat plane, and theold/ rebuilr 350 had a different angled plane. Just curious.

 

a 305 bored to a 350 would shred. bored 30 over is the same as .030 over. Overall you add only a couple cubic inches but it changes the torque profile of the motor. The stock 350 block may be bigger than a 305.... infact I would assume so. however, it is possible to stroke a motor out to a 350 from 305. This includes creating a longer path of travel for the piston by using a different crank/rod setup. I am not real big on the older motors, so i dont know if a 350 stroker kit is readily found for the 305. but a common is the 350 to 383 lt1 stroker kit.

another note on boring, my buddy bored his 5.0 (302) mustang i think..... um.... .040 over? anyways, it went from a 302 to a 306. Doing that big of a bore (~350)would give you paper thin walls on a normal motor and it wouldnt hold up to the stress of its own power.

 

Externally the blocks are the same dimension, internally the casting are different to accomodate different size pistons. The 305 and 350 have the same stroke dimension, but the 305 bore is 3.74" while the 350 bore is 4". The 305 cannot be safely bored to 4" whitout making the cylinder walls too thin or actually cutting into the water jacket.