Cobra Jet casting number

Apologies if this is posted elsewhere but where do I locate the casting number for a 428 Cobra Jet block? I did find the VIN numbers on the rear of the driver’s side cylinder head but I want to know if the block is also numbers matching. Where do I look. 1970 Cougar Eliminator, 428 CJ, 4-speed.

Thanks in advance,

Try poking around on the Cobra Jet registry. The engine block page is here:

For a 1970 CJ block you will only find the casting date, it is by the oil filter adaptor.

This is the casting date on my 70 428PI.

Thanks for the info. I’ll check it out.

Externally with the engine in the car there is not any way to ID a 428 CJ block. The date code will tell you what day that block was cast, but the block could still be a 390. Or a 360. Or a352.

For your car the VIN was supposed to be stamped on the rear face of the block near the cylinder head mounting surface. If you carefully clean the area with solvent and a rag, then take a photo using a cell phone with the flash turned on, you MIGHT be lucky enough to see it. If you already found the VIN stamped on the block then you indeed are likely to have the original 428 the car was born with. I would take photos and keep the photos with the car for future reference.

OK, I found the casting number at it is:

It seems to be “9K31”; does that mean October 31, 1969? If so, that would be even more spooky as this car is called Project Freddy (Cougar, not Kruger) but the motor would have been cast on Halloween day in 1969?

Yes on the East foundry line, first shift.

Yeah, 9K31 would be a casting date of Oct 31st, 1969.
Compare that with the build date for your car on your Marti Report.
Looks like the block was swapped out at some point. Maybe a casualty of the racing history?

As far as I know, it is most definitely a casualty of the racing history. And now the big question is, “is that the same block that was in it when I bought it 50 years ago?” or has it been replaced again since I owned it? I plan on dropping the oil pan and seeing if it looks familiar on the inside. There are a few clues that would tell me if it is the same thing that I saw inside of it when it was newish.


70scj4spvert said, Royce, what does the number 12 stamped next to the casting number mean on an scj block?

Fixed the links.

There is no such thing as an SCJ block. All 428 blocks were identical. Some decame SCJ’s. Some became CJ’s. Some became cop cars. Some went into Colony Park wagons. Some went into T-Birds. Some went into LTD’s.

If you can show me a photo of what you are talking about I could likely explain it.

Probably added by a machine shop during service work.

Fixed the links.


Here is a picture of the back of the block. Looks like a big “C” or it could even be a “G”. Whaddya think? CJ?

Here is a photoshopped enhanced view of the casting mark rotated to right side up…

Thanks in advance,

I’m going to say it was up side right to begin with. I think the guy on the foundry floor was in a rush and you can not erase a minor mistake. This proves it is a 428. The CJ comes from the heads more then anything else.

This is the “C” scratch on my 428PI.

I would say you have a CJ as you have the “N” heads and the correct intake. If I recall yours has headers instead of the correct exhaust manifolds. I think your good with this block.

All 428 blocks should have the big “C” scratch on the rear bulkhead sand cast mold starting about August 1967 and going until the end of production. Nothing special for the 428CJ or SCJ - it was all 428 engines whether they were for a cop car, a 428SCJ, a 428 CJ, or granny’s Colony Park 428-4V station wagon.

I have the original cast iron exhaust manifolds. I’m having them powder coated in a deep slate color so that they look like new cast iron.

Didn’t some have an A scratch?