Need help deciphering engine codes
Thread Starter
Pro
Joined: Jul 2011
Posts: 511
Likes: 34
From: NW Michigan
Need help deciphering engine codes
Hi all-
For multiple years I have tried to piece together what it is I have under my 1980 4-speed Vette's hood. I give up. Online resources have led me to no definitive answer... The VIN derivative is 15J217257, which does not match my VIN of 1Z878AS428930. The engine pad is V04I7CMJ. The block casting number found on the driver's side near the bell housing is 3970010.
Much of what I find online conflicts or is unclear... A 1974 350? A 1980 305? Seems that most CMJ codes were automatic cars... But one online source does say casting 3970010 was used through '79 for Vettes...
Anybody here know better than I?
For multiple years I have tried to piece together what it is I have under my 1980 4-speed Vette's hood. I give up. Online resources have led me to no definitive answer... The VIN derivative is 15J217257, which does not match my VIN of 1Z878AS428930. The engine pad is V04I7CMJ. The block casting number found on the driver's side near the bell housing is 3970010.
Much of what I find online conflicts or is unclear... A 1974 350? A 1980 305? Seems that most CMJ codes were automatic cars... But one online source does say casting 3970010 was used through '79 for Vettes...
Anybody here know better than I?
Last edited by SciVette; May 6, 2018 at 01:56 AM.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
J is the plant code for Janesville, Wisconsin. The 5 is likely to be 1975.
Your VIN shows a base engine car from May, 1980.
Flint, Michigan engine plant April 17th, probably meant for an Impala.
...1Z878AS428930...
...The engine pad is V04I7CMJ...
Team Owner
Joined: Sep 2006
Posts: 31,270
Likes: 4,362
From: Westminster Maryland
Hi SV,
"The block casting number found on the driver's side near the bell housing is 3970010."
The 010 block may be the most common small block casting Chevrolet used. There were literarily millions of of them cast.
In the late 60s and 70s the Flint engine plant (where the sb engines for Corvettes were built) was assembling 5000 engines per day in as many as 100 configurations from those castings for use in all sorts of Chevrolet vehicles.
Regards,
Alan
"The block casting number found on the driver's side near the bell housing is 3970010."
The 010 block may be the most common small block casting Chevrolet used. There were literarily millions of of them cast.
In the late 60s and 70s the Flint engine plant (where the sb engines for Corvettes were built) was assembling 5000 engines per day in as many as 100 configurations from those castings for use in all sorts of Chevrolet vehicles.
Regards,
Alan
Le Mans Master
Joined: Jan 2001
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Thread Starter
Pro
Joined: Jul 2011
Posts: 511
Likes: 34
From: NW Michigan
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
so your engine block was cast on april 10 1975
your engine block casting number is 3970010 which was very typical of all small blocks cast in 1975.
it was cast at the flint engine plant and then machined and assembled in april 17th, 1975 and built as a 350 cubic inch 145 ( 2 barrel ) horsepower passenger car engine ( impala, bel air, caprice ) with an automatic transmission.
then shipped to janesville wisconsin to be placed into the big 1975 chevy with a vin# ending in 17257 that was stamped in the assembly line at the car assembly plant.
at least that is what my book tells me.. other results may vary.
your engine block casting number is 3970010 which was very typical of all small blocks cast in 1975.
it was cast at the flint engine plant and then machined and assembled in april 17th, 1975 and built as a 350 cubic inch 145 ( 2 barrel ) horsepower passenger car engine ( impala, bel air, caprice ) with an automatic transmission.
then shipped to janesville wisconsin to be placed into the big 1975 chevy with a vin# ending in 17257 that was stamped in the assembly line at the car assembly plant.
at least that is what my book tells me.. other results may vary.
Thread Starter
Pro
Joined: Jul 2011
Posts: 511
Likes: 34
From: NW Michigan
And now resides in a 1980 4-speed Corvette with an Edelbrock Performer intake and an Edelbrock Thunder Series carb... Ha! Sometimes I wish this poor car could talk and tell me what happened to it! Where did it’s original motor go and what has it seen/been subjected to along the way before it made it’s way into my garage???
Last edited by SciVette; May 7, 2018 at 11:16 PM.
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