Classic/Antique Car Repair: 1966 pontiac with 1972 400 engine, pontiac gto yr engine codes

Question

engine numbers   good morning mr. russell
i spoke to you a couple of days pertaing to the 400 gm engine i have in a 1966 pontiac caatalina. well guess what i have a photo for you from the front of the right bank of the engine for you. i would like to know what this tells me according to the engine year, size and the amount of bolts in the main bearing caps it \\if it can
thank you
mioke

Answer
Hello Michael,

Thanks for the pictures. As they say, it's worth many words and helped. I did some more research and it appears you have a good find there! YR codes were on Pontiac 400's from 1965-67. This was the GTO 360 HP Ram Air version with 10.75:1 compression!

I couldn't find any data on the internals but obviously if any 400's were 4 bolt mains during this era, this would be one. For some reason, YR codes were automatics in 65-66 and manual in 1967.

If you want to find out more about these engines, there's a good mag. out there: High Performance Pontiac.

Hope this helps. Good luck to you!

Bob