pdege

Is it possible to have a 4 bolt main L48? I thought only L82s had 4 bolt mains. A gentleman said he had his L48 rebuilt and they put a 4 bolt main in it. How?

73-84 IMSA Widebody

There are a couple ways to convert 2 bolt to 4 bolt, rumor has it that coversion is stronger than original 4bolt. Someone will have an answer or a thread search will turn up some recent discussions

breathial

There are a variety of kits to convert a 2-bolt to a 4-bolt main.

The factory 4-bolt setup had the outer and inner bolts running parallel to each other, while many of the conversion kits actually splay the outer bolts, so they're angled away from the inner bolts. From what I understand, the added strength of this one operation is significant (but how much, I don't know).

Retrofitting a seasoned block for this, should make it a pretty stout basis for a high-performance application.

SanDiegoPaul

This is just a matter of using a 4-bolt block when you build the motor that's all. It is what I did when I built my 383 and thousands of others.

l88rocket

It is possible to have a l-48 4 bolt main block,I had a 79 l-82 with a 2-bolt main block and it was all original

Entropy

I think the question here is if you can have a base model vette (L48) and still have a 4 bolt main motor. The answer is yes, though it is rare. A small block is a small block (for the most part) and if you were building so many corvettes and needed a block, then you got whatever you had around (GM is renowned for this). Some L48 cars ended up with 010 blocks (according to the books I've read). When I rebuilt my 72 L48, it had an 014 block, and even some of those had 4 bolt mains in them (though mine did not).

Chances are the guy is not lying. Or he might have had the type of conversion that breathial suggested.

bams12

I have a 1980 L-48 matching numbers block with 4 bolt mains. It does happen. A forum member said he used to work on the line and if they ran out of 2 bolt blocks for the L-48 they would grab a 4 bolt to keep the line moving. Brent

63mako

True statement. I disassembled the 1973 L82 I was rebuilding to put in my car and it had the nodular crank instead of forged. Original pistons, Rods and bearings. Crank was correctly coded and dated but for 1973 L48 in a L82 original engine.

knbwag73

My 73, matching numbers L48 was overhauled over the past winter. To my surprise, it was a GM original 4 bolt main block.

Trent Mayo

I just pulled the motor out of my 75 L-48 last weekend to start on my rebuild and was surprised to find that it was a 010 - 4-bolt main too.

comp

what are the difference's in the L-48 "77" and the 350 in my 77 P/u ??
it's a 4 bolt block

Bob Onit

This is very surprising
Of course I could never be that lucky

So, the L-48 and L-82 were both 010 blocks but there was no external marking that designates 2 or 4 bolt main?

Entropy

From what I understand, there is no way to externally determine whether you have a 2 bolt or 4 bolt main block. Although there are lots of clues. The end of the block numbers (010 vs 014, 010 are generally 4 bolt, 014 are generally 2 bolt), the type of performance of the engine (high performance factory more likely to have 4 bolt mains) or truck engines. Dropping the oil pan dispels all myths.

trw

pdege

Yes, but that could trash all my hopes that I could have a 4 bolt!

Bob Onit

Unless your looking for 400HP the 2 bolt block will do just fine

mvftw

I thought that the '010' block meant it had 10% nickel and the '020' blocks (rare) had 20% nickel...or something like that...

Bob Onit

http://www.mortec.com/castnum.htm

comp

Hmmmmmm

Trent Mayo

Aren't we all though?!? haha

Bob Onit

Nope...399 HP will do just fine