Engine Research
Thread Starter
Intermediate
Joined: Jul 2025
Posts: 33
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Engine Research
I have an L88 427 that I'm trying to get some research on its value. The block is stamped with 3963512 and the heads are stamped with 3873858. I believe this is a 435/427. I picked it up from a friend that purchased it as a crate motor. I currently have it in a 1979 Trans Am that someone is wanting to buy just as a roller. I may part with the big block but want to see if anyone is looking for these specific stampings.
Any help would be greatly appreciated.
Any help would be greatly appreciated.
Race Director
Joined: Oct 2000
Posts: 12,661
Likes: 3,118
From: Shamong, NJ
The "512" casting block was used from 69-71 for every variation of 427 and 454, and in both 2 and 4 bolt main bearing configurations. The "838" casting heads are 66-67 396 and 427 closed chamber heads. It's not likely the block and heads were ever sold as a complete crate motor assembly.
On the right front of the block there should be a machined pad. If the engine was ever sold as a complete engine, and not just a bare block, there should be a series of letters and numbers stamped there to identify how the engine originally started life. The format will be a "T" for Tonawanda, four numbers for the month and day of assembly and a two letter code to identify the engine size and horsepower A block stamped T0213LR would decode as Tonawanda NY assembly plant (T), February (02) 13th day (13) 427/435 with a 4 speed (LR). Of course, what it started life as is no guarantee of what the engine is internally now, especially with a mismatched block and heads.
On the right front of the block there should be a machined pad. If the engine was ever sold as a complete engine, and not just a bare block, there should be a series of letters and numbers stamped there to identify how the engine originally started life. The format will be a "T" for Tonawanda, four numbers for the month and day of assembly and a two letter code to identify the engine size and horsepower A block stamped T0213LR would decode as Tonawanda NY assembly plant (T), February (02) 13th day (13) 427/435 with a 4 speed (LR). Of course, what it started life as is no guarantee of what the engine is internally now, especially with a mismatched block and heads.
