Small Block chevy rebuild

Ok So I have a 1985 305 TPI engine that originally came from a Trans Am that I intend to put in my 94 Astro van. I intend to rebuild it. At the very least put new rings and all new bearings in it. Depending on what I find when I tear ir down, it got me thinking, If I am going to have to put oversize pistons in it (which wouldn't suprise me being 22 years old) how much can it be bored out? Would I be able to bore it out to a 350 motor? If yes, would it be worth it? I know I would have to use a 350 crank so the engine is balanced, and I'm pretty sure a 350 knock sensor. So, is it feasible?

Hi Astronut, welcome to the forum. I hope you will enjoy it here.

I know that the "bore & stroke" of the 305 is 3.740" x 3.48", while that of the 350 is 4.000" x 3.48". Can this be of any help in comparing as to know how much you can bore it out?

Umm.. unfortunately not really. What I was really concerned with is, could it be bored out to those dimensions without haveing to worry about hitting a coolant passage or if there was enough metal between the cylinder walls to accomodate the larger bore.
Unfortunately I'm not too familiar with car engines, and I've never owned a small block before. I know they are a very common engine with lots of performance accessories. Knowing this, it's just an "assumption" on my part that I could do it without problems, but I wanted to be sure.

Astronut, I'm afraid you would need a detailed diagram of the unit for that mentioning the exact size of the wall. Maybe you can get to a car-depot (garage) and ask if they have a 305 TPI at hand so you can measure it yourself?

Well I think I got my answer. It seems that it is next to impossible to do this. I heard of one person doing this in a strictly racing application, but this is for my daily driver, so that is out of the question.

Sorry to hear that.

you should be able to find a 350 reasonably cheap, thats what I did with my 84 Z28, I t was well worth it, the 305 is like gm's mistake. Very low horsepower for a v8