1969 '7115 427 crankshaft usage

[Steve Antonucci]

I was recently involved in a discussion over the factory usage of the '7115
crankshaft of L-88 & ZL-1 fame. This basic topic had been discussed here
a few times over the years and I was wondering if any members here can
expand on this for me.

I know the '6223 crankshaft was used in L/78 & L/34 production. Obviously, the
L/78 application used cross-drilling & tuff-triding. I learned here that the
'6223 crankshaft was also used in the L/68, ( L/36 also I believe ), and the
L/71 & L/72. I know that the L/71 & L/72 got the cross-drilled & tuff-trided
version of this crank as well.

I had always heard the the 427 crank had heavier counter-weights to offset
the increase in piston size. I believe Colvin states this in his books. Based
on the number of members here with 427's with '6223 cranks, I now wonder if the
only applications for the '7115 crankshaft were the L-88 & ZL-1. I expect this
was because of the major power differential as well as the hugh domes on these
two particular pistons ( probably the same piston anyway ).

Can anyone tell me if there were any other crankshafts used in the '69 model
year for passenger car 427 ( Corvette ) applications?

Thanks,
Steve

[Joe L.]

Re: 1969 '7115 427 crankshaft usage

Steve----

The "7115" crankshaft forging was used only for L-88 and ZL-1 and only for the 1969 model year (+ later SERVICE L-88/ZL-1 engine assemblies).

The "7115" crankshaft forging which was used for GM PART #3967811 (and MAY have been used for the earlier GM PART #3942411). Most other 396/427 forged crankshafts were based on the "6223" or "3856223" forgings.

The GM #3867811 crankshaft was designed for use with the heavier connecting rods and larger size connecting rod bolts used only for 1969 L-88/ZL-1 427's. It also differed from earlier crankshafts by virtue of the fact that it was forged from 5140 steel alloy. All other big block forged crankshafts (through 1969) were forged from 1053 steel alloy.

[Richard L.]

Re: 1969 '7115 427 crankshaft usage

I have a new over the counter CE L88 engine short block, assembled in 1967 with a 68 CE stamp. The crank is a 7115 and the pistons are the floating type with 3/8" rod bolts and the 3904367 cam.

[Joe L.]

Re: 1969 '7115 427 crankshaft usage

Richard------

I have no record of the '7115' being used for anything other than the GM PART #3967811 crankshaft and that crankshaft was not released until the 1969 model year. However, as I mentioned, it MAY also have been used for the GM PART #3942411 crankshaft which was also an L-88 crankshaft used for the 1968 and early 1969 model year. It would seem unlikely to me that this would have been used for a 1967 assembled short block, though.

A few questions:

1) Where are you getting the part number for the camshaft?

2) What is the PART number of the short block assembly (on crate or tag)?

3) What is the CASTING number on the block?

4) What is the CASTING date on the block?

[Richard L.]

Re: 1969 '7115 427 crankshaft usage

Joe here is the data that you request:

Cam number stamped on the end of cam---4367
Pad stamp number---CE851165
Block cast number---3916321
Block cast date---H-19-7
Crank cast on counterweight---7115

Joe, this short block is brand new and I disassembled it to clean it up. It was sitting in a fellows garage since new and I purchased it. As I disassembled it I took pictures of each part. It had all the original factory markings on each part. If you are interested in seeing the pictures I can email them to you. I think this engine is fairly rare (for an L88) with the floating pins, 7115 crank and 3/8" rod bolts. Your comments!

[Steve Antonucci]

Re: 1969 '7115 427 crankshaft usage

Richard,

I would also like to take you up on getting copies of those images.
Can you post them here? Or, send them to my email address?

Steve

[Joe L.]

Re: 1969 '7115 427 crankshaft usage

Richard-----

This engine is a 1968 L-88 short block that was manufactured in late 1967. 1968 and early 1969 L-88 used crankshaft GM #3942411. Previoulsy, I could not verify if this crankshaft used the '7115' forging. However, your engine seems to provide "empirical verification" (which is always the best kind).

I did a little more research, too, and I'm finding conflicting information regarding the '7115' forging. From what I can find, it looks like it might have been around since 1966 or, possibly, even 1965. However, none of this is GM-sourced information. Plus, I cannot figure out what applications that it was used for. It's possible, though, that it was used for some HD truck applications. I have very little information on HD truck components.