Engine Codes

Q: Engine Codes

I am currently in the process of having my engine for my 1967 400 Convertible rebuilt. The mechanic has cross-referenced the (YD) code to a 1967 400, but it says it is a 2 barrell, and my engine has a 4 barrell. I am unable to find a cross reference for the engine code under the 1967 sectioin of this site. I do not see the letters referenced in this section. Can someone help me?

The code on the block is: 0081718 YD
Also stamped is: 20P105982

A: The 20P105982 is your clue to what that engine really came from. The first zero means it’s from a 1970 car, and the letter “P” means it was from a car built at the Pontiac assembly plant, where that year they were building full-sized cars like Catalina and Bonneville. The YD for that year indicates a 2 barrel 400, 290 gross HP from a Pontiac, meaning big car. Although the chart I have says a 10.0:1 compression ratio, it does not say what head cast numbers were used.

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