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I have a 70 corvette with a BB 454 with matching numbers, engine and body. The block casting number is 3963512 with a stamp of T03I8CZU. The head casting number is 3964290. I am having to replace the engine and trying to order a long block from ATK/Vege-Gearhead. However, they tell me they do not have my numbers in their data base, so not sure which of their engines to order. Is this a common problem? Has anyone else had this problem when replacing an engine?
You are tagging on a nearly 20 year old thread. You should start a new one but I would ask first why are you wanting to replace the engine? Your car is worth a hell of a lot more with the original engine.
You are tagging on a nearly 20 year old thread. You should start a new one but I would ask first why are you wanting to replace the engine? Your car is worth a hell of a lot more with the original engine.
Exactly what I was wondering. Why not rebuild the original engine?
Now I am worried about your builder..... The 70 Corvette only had one BBC engine option available, a 390HP 454 called the LS5.
The CZU block stamping is correct for a 4 speed version. a CGW stamp for an auto version and a CRI stamp for a 4 speed version with Transistor Ignition. That is why there are 3 stamp codes.
Only took me a 3 second Google search to find that. Your block casting number sounds correct also.
And the car is probably worth 2-5-?? K dollars more with the factory original engine, so why change it?
It is worth it to salvage the original block even if something is wrong with it.
I was quoted $2400 for a "correct" replacement block for my 72, with correct casting numbers, correct block casting date codes and "supposedly" correct pad re-stampings. Which most experts can usually tell were re-stamped anyway. It wasn't worth it to me, but my car is very far from numbers matching anyway. For others I guess it is.
I found 4-5 sources for blocks. Just google "date coded big blocks" or similar.
Short version: ran in Jan 2021, decided to sell it in May when it would turn over but not start; after trouble shooting ordered new carb; took four months to get, put it on and engine/pistons/valves (see piston Piston 3 Piston 7
pics) had locked up; no idea where leak is, head, block, gasket, gouge damage in piston sleeve, etc; thought it is worth $2-3,000 for long block to get better offers to purchase.
That is by no means the end of that block.
One of my numbers match 327 C2's had similar damage to one of its cylinders. I was having the engine rebuilt anyway and simply had that cylinder sleeved. Excellent fix and saved the original engine. I also had a 1966 GTO with it's orig. engine which had sat for years exposed to the elements. Cylinders were rough and it had previously been bored to .060. I had all eight cylinders sleeved back to standard bore. Another good solid fix and another good save.
If I had your car/block, I would remove all the pistons, soak and then drive out the corroded piston, it will probably come out in pieces but it is much softer than the cylinder walls so that's OK. Take the block to your machinist, have it checked over and ask him about installing a sleeve in that one cylinder.
A numbers matching big block 1970 Corvette is one of less than 5,000 built in a short run year. It is certainly worth saving.
Cheers, Greg
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Re: 3963512 What does it mean? (mixtli)
3963512 blocks have a LOT of wall thickness so you may not have to go the sleeve route.
