So I just bought a 22 roadster hot rod. The mechanic that works for the estate I bought it from told me the engine is a 425 super something or other. It sounds cammed up but he swears that other than the intake manifold and the carb everything else is stock. What should I be looking for to better dial in what this engine really is and where it came from? He says it came out of a 65 I believe.

 

Oldsmobile nicknamed their V8 engine rocket.

​​​​​​The 425 was nicknamed super rocket. It is as the nickname implies. Their greatest engine. It came in their finest cars.

It's best version for 1965 was rated at 370 HP and 470 lb ft torque. My guess being that you have an after market intake and carb. Is that it's a lesser version, but who knows ... It's extremely powerful regardless. Base 425 for 1965 was rated 300 HP and 430 lb ft torque.

 

He did mention 380 hp at the crank

 

What codes should I look for and where would I find them?

 

No Olds engine from the 1965 model year was factory rated at 380 HP. "Super Rocket" was simply Oldsmobile's marketing name for the 425. It could have had anywhere from 300 to 360 HP gross, depending on which one. There's no way to know without tearing the motor apart and measuring valve size, piston dish, and cam profile.