Lou's1966442

I have a 1966 F85...recently purchased. Was told engine is 455. Doesn't really matter to me...I just liked the car. Anyway, I looked at the numbe to the right of the oil fill tube. The heads have a "C". Intake is from Edelbrock. Carburetor is a Holley double pumper...not sure of cfm. Anyway, can someone please decipher what I have?

2blu442

Welcome to the site Lou! Please share some pictures of your car with us when you have time. The block number you posted is for a 425, but the bore is the same as a 455. If someone had put a 455 crank and rods into it that would have made it a 455. The only way to know for sure is look at the tail of the crank behind the flexplate/flywheel. But if you have a good running car I'd encourage you to just enjoy it! If something happens and you have to tear it down you can evaluate what's inside it then. The C heads were used from 1967 through 1969 on big block engines. The 1967 did have an application stamp on the passenger side front of the head. If you find that we can tell you what that head came off of, but over the years who knows if those heads came with the motor or not. All C heads could have come with large or small intake valves. The application code would say what they were from the factory, but that again could have been changed from small to large valves by a competent machine shop.

John

Lou's1966442

Also, is there numbers/letters on both block and heads to verify originality to one another? If so, wouldn't the "C" heads verify the block as 66/67?

joe_padavano

C heads were used on the 1967 425, but obviously can be bolted to any Olds block. There is nothing that ties a particular head casting to a particular block casting. At this point, it really doesn't matter. You've got a 425 block with C heads. It's a nice combo. Go with it.

Lou's1966442

Thank you Joe! I appreciate your knowledge and input!

Lou's1966442

Also, would the "C" heads have the small or large valves (considering they are original)

2blu442

They could be either one. Olds used the same castings, then cut the valve seat size for the application. There's no way to tell without removing the head and measuring the valve.

Lou's1966442

Thank you sir!