What To Build?

[CATMAN]

The 75'(?) 350 in my 71',(it was in the truck when I bought it); is getting a little tired. Using the #'s off the right head, I believe it is either a 75' or 76'(vo523flc), and used to be a 2bbl, I don't believe it is a truck motor. I have a 80' Chevy farm truck with the original 350, 4bolt, 4bbl(v1203tkk). For a reason I'm not sure of, I am leaning toward re-building the 80' 350, to put in the 71', and not the 350 that is currently in there. If I do this, should it not be a staight forward bolt in? Having the later model 350 already in the 71', it is already running with HEI ignition. Thanks for any insight!

[Slonaker]

AFAIK they will both be the same. Everything should bolt up to either one. The dipstick should be on the same side for both years, I think. You might look up the numbers on the back of the block by the HEI on mortec.com and make sure both are 350s. The heads could have been swapped, and one could be a 305 or a 307 or something. Surprises like that are not good. The 4 bolt mains are supposed to be better for performance applications, but should not make a big difference unless you are trying to make big horsepower numbers.
Slonaker

[piecesparts]

A 2 bolt main will stand up to just about everything a street driven vehicle will need, however we ALL love a 4 bolt main motor. The newer motor compared to the older motor is a NON-issue. The bolt patterns are the same on the important parts. As a matter of fact I have put earlier motors in my 84 and my son's 86, to get the older "heavy block design for stroking". The items to look for are the number of bolt holes in the front of the heads, so that all of your accessories will hook up, and where the dipstick is, just make sure you get the right stick in the hole. I would like to recommend a couple of things to think about while you do your rebuild. Look at a bigger oil pan, the extra oil and area will give more cooling capacity of the oil and that is important. I run a 7 quart moroso pan on my motors. Also look to make sure that you have the right distributor gear for you application. If you choose something like a roller cam, then you will need the hardened gear on the dizzy. Everything else is a fact of taking it out and re-installing it.

[f.monroe]

With both engines being basically the same , I would build the 80 motor . That way you can keep the engine in your truck and have it running and moveable until your new engine is ready . Then just swap in the new power plant and you have very little down time . Just an opinion . Frank

[CATMAN]

Thanks Everyone!