I was checking the value of a 69 Big Block 396/375 engine & Hagerty has 2 listings, 1 is for a L78 & the other is for a L89. If both came with the big block 396/375 engine how can one tell the difference between the two?
Hi there! While the displacement and output are rated the same, the difference is that the L78 has iron heads and the L89 are aluminum. Original, documented L89 cars are incredibly rare, thus they carry a substantial premium. L89 engines usually have the aluminum heads in a bare finish rather than painted. You can also look for a Winters logo on the casting.
The trick with identifying an ORIGINAL car is tough though. These car cars that are more often cloned than real. Documentation is an absolute must for authenticity as the VIN does not contain any information about what engine the car was delivered with originally.
The VIN would indicate weather the car came with a 6 or 8 but beyond that you are correct that it would not indicate which 6 or 8 it came with. You can use a combination of engine ID and VIN stamping on the block to see if it was an L78 and if it came in that car, but to determine if it had the L89 heads you would need the build sheet or Protecto Plate.
Yes, you are correct. My oversight. Too bad GM was too lazy to just include a digit for the engine in their VIN. Would be so much easier to call out a clone being passed for a real car. But then again, I doubt anyone thought these cars would be collectible when they were making them.
They did include it in the VIN but not until 72. I do agree with you that I don’t think anyone at the time knew that these cars would be so valuable.