Ok, i know it was prolly asked before..but i didnt see an answer to my specific question..the 305 and 350 share the same block, but i'm told the coolant passages are routed different, thus making it impossible to bore out a 305 to be able to be stroked..so i am curious if any of you have ever done it before..and if so do you have pics?

 

305's do NOT share the same block as the 350. 2 completly different cores. The 305 is based off of a 3.735" bore whereas the 350 is based on a 4.000" bore. It is physically impossible to bore a 3.735" bore out to a 4.000" and not hit something. Yes, they are identical externally as far as bolting things up. Internals are completely different.

So, in short, it is impossible to get a 383 from a 305 block. A 305 block with a .030" overbore and a 3.75" stroke yields a 335cid.

 

That, to my understanding, is also the largest that you can safetly overbore a 305. Any bigger than that and you would be getting to close to the water jackets and lower the structural integrity of the engine.

Bruce (90RS305)

 

I have seen .060 305s. Thay are the same as any other engine, sometimes yes, sometimes no, jsut gotta make sure to get it checked.

 

The 305 and 350 DO NOT share the same block. it's the same on the outside, but the internals are different: the 350 has a 4.000" bore, but the 305 has a 3.736" bore ..... more than ¼" different. It is not possible to bore a 305 to anywhere near the 350 bore size.

The 305 and 350 share the same stroke, 3.48"; and even the same crank casting in most of them, in any given year. For example, in 2-piece rear main seal 305s and the 350s that were being built at the same time (77 to 85), it's the 442 crank casting. (casting, not forging) So, if you take a 305 block, and put a 350 crank in it, you come up with {drum roll please} a 305! {cymbal crash} Or, you can take a 400 crank with its 3.75" stroke, and by various machine work and parts matching, put it into a 305 block bored .030" over, and come up with a 334; or put it into a 350 block in the same overbore, and come up with a 383.

But, you can make a 305 into a 383, no problem at all. It's easy. Just 3 simple steps:

1. Throw entire 305 in the trash

2. Get a 350

3. Add a 3.75" stroke crank

Done!

But you cannot do it if you retain any of the 305 parts.

 

4 steps RB.

3.5: Clearances

 

Bah..... details. Consider it part of step 3.

Step 1 is the most important one.

 

Agreed, thats what I did. 305's just arnt worth the effort.

 

There's 5 of them sitting on the floor of my garage right now. Totally useable, I just can't get rid of them.

 

they work really well for boat dock anchors around here...LOL

 

...sold a complete 305 tbi for 50 bucks, i think I came out good on that deal