I think I'm about to jump ship from Pontiac and jump into a 1970 Cutlass resto. I always have my eyes open for any pre-73 muscle cars, and so yesterday I spot a Cutlass 3/4 hidden under a car cover. I get a conversation going about another car on the property (junker) and then slowly turn my attention to the car under the cover. The elderly man then shows me a 70 Cutlass S, white gold/tan interior buckets/console, 455, 12bolt posi, nice rallyes etc. He's the 2nd owner, swears it is an original factory installed 455. It's not an SX (there's one of those about 5 miles from me behind a shed), and it's not a Hurst or 442 (there's a guy with a field full of those rotting away close by too, including a 69 442 convertible 4 speed W-27)... so is it possible? Could you order a 455 in an S. I searched the forum, nothing... If it's a swap, someone did a very very good job. Not one rigged wire, clip, or piece looks out of place.

 

didnt the cutlass s begin in 71?

 

It's very easy to determine if the car has it's original engine. There's a VIN-derivative stamped on a pad on the block. The pad is located on the driver's side of the block, just below the deck surface at the front - roughly below and forward of the No. 1 exhaust port. This pad is usually covered with crud and will be partly obscured by the PS pump bracket. You will likely need to hit it with a wire brush to read the numbers.

The pad will have a nine digit number. The first character will always be a "3" to signify Oldsmobile Division and will match the first character of the car's VIN. The second character signifies the year and will be a "0" for 1970. This should match the sixth character of the VIN. The third character is a letter signifying the build plant and should match the seventh character of the VIN. The final six digits are a sequential build number and should match the last six characters of the VIN. This would be a "numbers matching" engine (well, at least the block) and would prove that this engine was factory installed.

Another clue to look for is the transmission - if it's an automatic it should be a TH400. Olds NEVER put a TH350 behind a big block. Note that the TH400 is longer and the crossmember must be located at the rear-most set of holes pre-drilled in the frame. Look for evidence that the crossmember was previously bolted in the forward position, indicating a TH350 was installed at one time. I found this on a supposed Supreme SX, for example. Note that this does not apply if the car is a manual trans.

Also, a factory big block car would have come with a Type O axle with the smooth 12 bolt cover (though it is still a 10 bolt ring gear). Canadian built cars did get the Chevy 12 bolt, however. A small block car may have come with a 10 bolt cover on the axle.

By the way, it isn't terribly difficult to bolt a 455 into any Cutlass and make it look like a factory job.

 

Joe's tips are correct - here's a link to the VIN pad location on my website (scroll down the page):

http://www.highoctaneauto.com/newpage66.htm

Yes, you absolutely could get a 455 in a Cutlass 'S' in 1970-72 with a TH400 or manual trans.

And the Cutlass 'S' started in 1968.

Terry