Anyone know this block GM 41 3970010
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: N J
Anyone know this block GM 41 3970010
I know its a 350, (I believe), has a drivers side dipstick and a "8" for its build year. I would think 1978 cause the small pad in the front of the engine is the smaller square shape not the longer more narrow older style pad for 1968. The pad is smooth so theres no engine codes. Its cast GM 41 by the 3970010. I thought it was an L-48 but I know they had a rh dipstick. Thanks for any help.
Intermediate
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From: Rolling Hills Estates CA
Yes, it's a 350 cid block, hi-performance application. Those ones were manufactured by GM between '68 - '76, but were being manufactured after that in Mexico. The Mexican blocks have the "Made in Mexico" raised letters next to the casting number.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: N J
Thanks for your help, It dont have the Made in Mexico script on it, but with the 8 for the year it was cast (78 I would think cause of the smaller pad so it cant be a 68) and the lack of the mexico script I am still a little confused. Date on rear of rh side of block says J 7 8 Thanks
Last edited by John 65; Jan 22, 2007 at 07:02 PM.
Intermediate
Joined: Sep 2006
Posts: 36
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From: Rolling Hills Estates CA
Thanks for your help, It dont have the Made in Mexico script on it, but with the 8 for the year it was cast (78 I would think cause of the smaller pad so it cant be a 68) and the lack of the mexico script I am still a little confused. Date on rear of rh side of block says J 7 8 Thanks
Racer
Joined: Oct 2005
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From: Grand-Falls New Brunswick
HI GUYS
Looking through my 1965-69 chevrolet by the numbers book this block came into production sometime in late april or early may of 1969 and was used through 1975.It was produced in 2 and 4 bolt application except for 1969 which were all 4 bolt main.They also explain that the date should have three digits,is there a digit that maybe you don't see.Or maybe not everything in this book is true.
Looking through my 1965-69 chevrolet by the numbers book this block came into production sometime in late april or early may of 1969 and was used through 1975.It was produced in 2 and 4 bolt application except for 1969 which were all 4 bolt main.They also explain that the date should have three digits,is there a digit that maybe you don't see.Or maybe not everything in this book is true.
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Thread Starter
Le Mans Master
Joined: Dec 2003
Posts: 5,380
Likes: 415
From: N J
Thank you all for your replys, unfortuntaly the pad is smooth, no codes. I guess I dont have anything special out there under the hood 
I questioned it cause I would have sworn the dipstick was on the other side for that year. Appreciate all your help.
I questioned it cause I would have sworn the dipstick was on the other side for that year. Appreciate all your help.
Last edited by John 65; Jan 22, 2007 at 08:04 PM.
Advanced
Joined: Aug 2006
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In my experience, the "010" block is the most common pre-87 block. They were used in the last 302 and 327 motors, as well as hundreds of thousands, if not millions, of 350s. I have a 69 4-bolt version as well as a 77 2-bolt.
Some had a higher tin and nickel content, designated by 010 and 020 cast into the block to the left and right of the front and rear cam journals. I believe these were mostly used for the 302 and LT1 350s, but some may have been used in trucks.
BTW, one of David Vizard's books says the 010 block was made from 68-79. Mortec.com shows 69-80.
Some had a higher tin and nickel content, designated by 010 and 020 cast into the block to the left and right of the front and rear cam journals. I believe these were mostly used for the 302 and LT1 350s, but some may have been used in trucks.
BTW, one of David Vizard's books says the 010 block was made from 68-79. Mortec.com shows 69-80.
Le Mans Master
Joined: Feb 2006
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From: "cutesy" TN
The bigger trucks (1 ton and bigger) also had forged crankshafts. I am sure they are not "high performance".
1st Gear
Joined: Apr 2020
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as I've been looking through this thread, I seem to have a question. I just bought a motor for street stock dirt racing. Motor is a 3970010, 010 stamp, a ck227? Stamp, along with H24 WR and a g12, then a bear the harmonic balancer, V1203cmb, punched in the block with 58750607 stamped onto that, can anyone figure this mess out, I believe it's a 350 made in flint engine co. On Jan 20? 1973 maybe? And according to the CMB, A 350 from a truck, 2 bolt main..please help