1975 Engine block Info

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Jan 2, 2022 | 07:18 PM

johnfin

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1975 Engine block Info

Any of you guys know alot about the 3970010 engine block?

Jan 2, 2022 | 08:08 PM

PJO

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From: Laporte, IN

GM engine block # 3970010 was used as early as 1968 on some 327ci engines. From 1969-1979 it was a 350ci engine. It could be a 2 or 4 bolt block used in cars, trucks and even corvettes.

Jan 2, 2022 | 08:15 PM

lars

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From: At my Bar drinking and wrenching in Lafayette Colorado

Casting number 3970010 is a common small block engine casting. It was used in 1968 on the 327 2-bolt engines used in the "A" body, and it was used as a 350 block from 1969 through 1979 as both 2-bolt blocks and 4-bolt blocks in Chevy cars, trucks, and Vette. It was used in horsepower applications from 185 through 370. A common, universal block casting.

Lars

Jan 2, 2022 | 08:53 PM

johnfin

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Did the L42 and L82 blocks have the same casting number?

Jan 3, 2022 | 06:03 AM

4-vettes

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Well John. what matters most is the number on the stamp pad. The block casting number is just that. A foundry number of a casting. How it was machined after that is what matters. A L48 is a 2 bolt main. L82 a 4 bolt main. And of course the L82 got better/stronger internals.
I have had my 77 for over 30 years. I know it's the original engine. the stamp pad verifies that and know the history of the car. But I have never once looked for a casting number from the foundry.

Jan 3, 2022 | 06:13 AM

Gordonm

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From: Forked River NJ

Quote:

Originally Posted by johnfin

Did the L42 and L82 blocks have the same casting number?

Yes

Jan 3, 2022 | 07:36 AM

johnfin

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Block

I read that the 010 block was stronger leading me to believe it was for the L82

Jan 3, 2022 | 07:44 AM

Jebbysan

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From: New Braunfels Texas

Quote:

Originally Posted by johnfin

I read that the 010 block was stronger leading me to believe it was for the L82

There is a LOT of misinformation out there......50 years or fairy tails about "high nickle" blocks and this block being stronger than that block......
Truth is.....the 010 Block was a "belly button" block......it was used for several different applications and most were NOT high performance.......
All L-82's were 010 blocks...but not all 010 blocks were L-82's.....
It is no better or worse than any other 350 cast in that era really......and the 4 bolt means about squat because you will spin bearings on a stock block before you pull a crank out of one.....I have built 500+hp 383's out of 2 bolt blocks that only had ARP bolts as a mod.

Jebby