4-bolt 350

[Space Cowboy]

I'm in the process of selling my 68 Vette. I had a guy ask me if it had a "4-bolt 350" in it. I don't know much about engine classifications, so how the heck do I know if its a "4-bolt"? I've never even heard that term before. I was just told it was a 350 small block when I bought it.

Thanks

 

[MaineShark]

"4-bolt" refers to the number of bolts holding the main bearing caps, which in turn hold the crankshaft in place. 4 bolts is stronger than 2 bolts (on the 350 block, anyway).

As far as I know, 'Vettes have always had 4-bolt blocks, from the factory. So, if your engine is original, then the block should be a 4-bolt. You can check the engine's casting numbers to verify what sort of block it is, and whether it is original. There should be a flat area in front of the passenger-side cylinder head with some numbers stamped in it. If your VIN number is on there, then the engine is original. In any case, if you post those numbers here, someone should be able to tell you what type of block it is.

Joe

 

[76L82]

Main journal caps for the crankshaft - they either came with 2 bolts or 4 bolts. Most people will argue that having a 4 bolt main engine makes it a stronger enigne...although I have heard from engine builders that they have made equal horsepower engines from 2 bolt engines and they perfomred just fine. There is no way externally to identify if you have a 2 or 4 bolt main engine. What you'll have to do is take the casting numbers off your engine and post them here. Folks that have a book that identifies casting numbers can give you a very good idea what you have.

 

[76L82]

Maine Shark is right...whoops..I said main journal caps..meant main bearings.

 

[Stallion]

"4-bolt" refers to the number of bolts holding the main bearing caps, which in turn hold the crankshaft in place. 4 bolts is stronger than 2 bolts (on the 350 block, anyway).

As far as I know, 'Vettes have always had 4-bolt blocks, from the factory. So, if your engine is original, then the block should be a 4-bolt. You can check the engine's casting numbers to verify what sort of block it is, and whether it is original. There should be a flat area in front of the passenger-side cylinder head with some numbers stamped in it. If your VIN number is on there, then the engine is original. In any case, if you post those numbers here, someone should be able to tell you what type of block it is.

Joe

His '68 might have a 4-bolt, but I'm sure of that my '78 has a 2-bolt. So, it's not all Vettes. He will have to look up his specific engine for the specs on it.

 

[CQRT]

If it's original . . .

If it's an original 68 small block, isn't it going to have a 327/300 in it ??

CQRT in AZ

 

[jclit]

I see Stallion says his ’78 L48 is 2-bolt. Is my ’78 L82 2-bolt or 4-bolt? I thought all Corvettes had 4-bolt mains.



Jim

 

[Space Cowboy]

Thanks all. That definitely answered my question.

DNewton

 

[rainman]

I think L-82's were 4-bolt and L-48's were 2-bolt.

 

[Space Cowboy]

Okay... I found the numbers on the passenger cylinder head. There were actually two sets of numbers, one on top of the other and one set was a different stamp type than the other.

The top set = VO3256KH (I'm guessing that the second character is the letter "O", and not the number zero)

The bottom set = 17D475048

Can anyone look this up for me and what is the difference between the two sets of numbers.

Thanks!

 

[Stallion]

Yup, your L82 is a 4-bolt main.

 

[Space Cowboy]

How do you know... where can I verify this?

Thanks!

 

[Space Cowboy]

Sorry... I'm not trying to be a pain. I trust your judement and findings, but I need to learn this stuff too.

How do I look this information up (on the internet if available) and what is the two different sets of numbers?

Thanks again!

 

[Vettehead Mikey]

Okay... I found the numbers on the passenger cylinder head. There were actually two sets of numbers, one on top of the other and one set was a different stamp type than the other.

The top set = VO3256KH (I'm guessing that the second character is the letter "O", and not the number zero)

The bottom set = 17D475048

Can anyone look this up for me and what is the difference between the two sets of numbers.

Thanks!

V indicates that the engine was built at the Flint plant. The last two letters (KH) is the code that indicates what spec of engine this is and it's original installation. I have no record that 'KH' was ever used in a '68 Corvette but it was used in '66 for the 350 horse engine. The numbers 03256 mean March 25, 1966 when the engine was assembled. Small block codes for a '68 Corvette were HT, HO, HP and HT.

17D475048 is a derivative of the VIN number for the car. One of the C2 guys could decode that for you.

 

[Vettehead Mikey]

How do you know... where can I verify this?

Thanks!

I don't think anyone was answering your question, your thread was being 'highjacked' - something that I always thought was rather rude and showed poor 'netiquette'.

 

[Space Cowboy]

Thanks Vettehead! I'm still wondering how Stallion determined I have a 4-bolt.

Maybe he'll reply back.

Thank for you information. At least it taught me something!

 

[GerryLP]

Hey, guys [and gals], try this web site http://www.mortec.com/wmotor.htm

They have a pretty good data base.

 

[Vettehead Mikey]

Thanks Vettehead! I'm still wondering how Stallion determined I have a 4-bolt.

Maybe he'll reply back.

Thank for you information. At least it taught me something!

He didn't - he was talking to somebody else (hijacking= rude)

 

[Space Cowboy]

Strange... I was curious about other numbers on the block. I look on the rear driver side of the block and had large numbers molded in... 3970010. When I looked at various searches all of them stated. 3970010....350...69-80...2 or 4 bolt.

So I guess I'm back to asking how do I determine if its a 4 bolt?

Sorry folks!

 

[Space Cowboy]

Now I know why I'm confused. I didn't realize my thread was hijacked.

I wish folks would start their own threads if they have other questions. Sheesh!