As a rule does a 350 block need to be relieved when making it a 383?

Say someone were to get a eagle crank, set of 5.7 balanced rods, and a balanced set of pistons............would it be important moreso than a 350 to have the whole reciprocating assy balanced?



What I'm getting at.

A friend gave me a fresh 350 someone spun a rod in and kinda messed up a piston it. Block is undamaged (going to have boiled and cam bearings though). Given I have to have the crank turned and buy pistons..........having priced eagle cast cranks on ebay for $149 shipped and pistons for about the same............had the idea of doing a 383. Figure the price diffrence would be about $150 if all else is the same.

I'm on a very strict budget and sure I'm missing something. This will be a street motor for my wagon.

Should I just go back as a 350?

Thanks, Kevin

Usually takes some grinding to fit the crank, although I hear some of the aftermarket cranks drop right in.

If I were you, I'd spend a little extra for the 383ci. I have a 355 and wish I would've just gone with the long stroke motor to start with.

Tough call, it's possible to build a 350 that will equal or outperform a 383 for the same money if you spend the money you would have used on the 383 rotating assembly on optimizing the combustion chamber and piston for the 350 by going to a small chamber head and D-cup piston vs. the more common flat top and 76CC heads to obtain the same compression. In other words a 9 to 1 355 with small chamber heads will run as good as a 383 with open chamber 76cc heads and flat tops if everything else is the same. But if you can squeeze together the money for both the piston/head combo and the 383 kit go for the 383. You'll be glad you did!

Oh yeah, I built a 383 back in '83 the crank dropped right in no problems the clearance issue is usually when you use 5.7 rods, I used the 5.565's.

if you're building, GMPP has the "pre relieved" 383 bare block

it will cost you more than 150 extra i can guarantee that! there are lots of little things people dont think about when converting..

If you are getting a whole new rotating assembly anyways, the cost difference wont be toooo bad.. but dont forget about putting on a different balancer and flex plate, and possibly a new starter if it doesnt match up. You will most likely need to grind out your block ( hopefully the machine shop would mock it all up to be sure nothing is oging to occupy the same space ) :)

it will cost you more than 150 extra i can guarantee that! there are lots of little things people dont think about when converting..

If you are getting a whole new rotating assembly anyways, the cost difference wont be toooo bad.. but dont forget about putting on a different balancer and flex plate, and possibly a new starter if it doesnt match up. You will most likely need to grind out your block ( hopefully the machine shop would mock it all up to be sure nothing is oging to occupy the same space ) :)
If you use the 5.7 rods you will definately have to clearance the block for them... I think I have some pictures of the block/rods/crank assembled where you can see the places the block is ground. If you want them just let me know... I can email them.

Thanks to all who replied........... due to some financial setbacks mid last week and now some medical problems as of yesterday I'm going to be doing good just to build the 350.

Aint life interesting...........