I have an 80 as well and I bought it with the big block in it. But I don't kno which one it is. How do I find out. Looking at the numbers on the spider it told me it's an Oldsmobile engine and may be a 442. But I want to be sure. They did replace the radiator to a hi performance one as well

 

Post a pic of the front shelf next to the oil filler tube.

 

I moved your post to a new thread. You'll get more views this way vs. resurrecting a thread that's 13 years old.

 

 

the intake manifold casting number indicates 307

We need more info but it looks like a 307

 

See this thread to help identify your engine.

https://classicoldsmobile.com/forums...engines-13691/

 

This is the location for the engine casting number between the oil filler tube and oil pressure sensor hole.

 

There is no such thing. It's a common misconception that 442s came with a 442 CID. In reality they could be 442 optioned and have anywhere from a 231 CID V6 to a 455 CID V8 when RWD.

Another misconception is caused by the fact that the most famous small block, the Chevy 350 looks small compared to a small block Olds. While a big block Olds upon initial view gets confused with small block Olds often because of the subtle difference in appearance. Unlike a Chevy big block that due to its enormous valve covers is instantaneously recognized.

 

This is my engine. Took off the carb to put on a 75 Chevy shortened. But gonna reinstall after repairs. I want to know do I have a big block or small block.

 

When YOU post a pic of the engine block casting number, we can tel you. See post #7 for where to look.

 

Its definitely a small block. The big block intake manifold is much larger. As Don71 stated your pics show the intake manifold to an Olds 307.

Modern Oldsmobile big blocks are either, 400, 425, or 455.

Here is your intake manifold matched with casting #, on bottom of screenshot.

https://www.chicagomusclecarparts.com/products/282122

 

Is your car a Calais ?

1980 442s came with blue small blocks...

As OLDSter Ralph pointed out in post #7 and #10 of this thread. That number sequence is key to identifying which small block you have.

1980 442s were Calais not Supreme. And the 442 engine in this case would be a small block 350. Very rare, one of the rarest 442s in history.

Otherwise it is my understanding that some early Olds 307s came with blue valve covers.

 

The intake is an A5 peanut port.intake. NOT great for performance, although a little torque plus on the low end. If the engine came with that intake, it's likely a VIN Y 307. 140 HP range.

Note the small ports and "A5".





86 and 87 442 (VIN 9) had 170 HP and used this intake. But the key is it had a thick balancer. Y engine balancers are super thin. You could almost shave with them. So look there. Doesn't mean someone couldn't have changed it, but...if the original carb is there, it's likely a 17086008 (Y engine) or 17086009 (VIN 9 engine). VIN 9 engines used cast iron exhaust manifolds and VIN Y had the stainless log tube exhaust. They used the 307 in later cars like Cadillac and stuff up through 1990 as well. They used the same 2 carb numbers previously mentioned from 86-90. Tow package Caddys and heavy framed cars supposedly got the VIN 9 engines and the others got VIN Y.

If that intake is on a 350 larger port head motor.....OMFG. No. Just...no.