ryan22

Casting # 3959512 dated 1974 was installed by Chevy dealership into 1966 Corvette as a replacement block, stamped "CE".

Can someone please tell me if they know whether this would be a small or large journal block ?
and/Or
tell me how to tell the difference ?

thank you-

MikeM

http://forums.corvetteforum.com/c1-a...olt-block.html

rongold

Good thread Mike pointed out, but 512 blocks were made in large & small journals, and with & without provision for a road draft tube. It depends what the original application was. 3955512 blocks were strictly replacement blocks and had to be made in many different configurations to match the original engine being replaced.

ryan22

The original engine/block being replaced was a 1966 327/350hp L79.

Does that mean this is most likely a small journal since thats what the original block was ?

jimh_1962

I have the same block with the same date in my 62. My block with the downdraft tube hole is a small journal block. Forged crank 4577 something like that. I built the motor myself and did the research on it.

JohnZ

It's likely that it's a small-journal, but you won't know for sure until you drop the pan and remove a bearing cap.

ryan22

John,
as ya can tell i'm not well versed with this, once i remove a bearing cap is there a measurement that needs to be taken to determine journal size ?

thx-

MikeM

The journal diameter on the SJ main bearing is 2.2978-2.2988. The LJ main will be bigger.

If that engine was built to be a direct replacement, it should have two bolt mains, forged crank, domed pistons, machined for rear block vent and the connecting rod nuts should be torque prevailing. That would also indicate a SJ crank.

If that block was for a '67 Camaro replacement, it would have LJ mains and a rear block breather.

It might be safe to say, if the block IS NOT machined for the rear block breather, it is a large journal block. I can't think of any exception.

ryan22

in case anyone is interested i have this block listed for sale in the C1-C2 parts section.

http://forums.corvetteforum.com/c1-a...r-oil-pan.html

thanks-

oldskydog

I think you meant 67 Camaro 350 as the 67 327 still had small journals.