350 and 327 [1966 - 1980]
MorTec.com has casting numbers and information
Chevy block with casting #3970010 is not a 4-bolt main block---1968--327 cid/250hp A body car---1969-79-350 cid/185hp--car , truck , vette.
Those may not be the numbers needed for correct identification. I've seen that 3970010 on many, many blocks. The block number you need is usually stamped into a small id plate just ahead of the right cylinder head. The head numbers are under the rocker covers, and can be difficult to read if they are covered in sludge, which is common. With the correct numbers, you could go to a website such as: http://www.auto-ware.com/techref/castnum.htm to answer your question.
It is stamped into the top of the heads where the valve springs are.
How can I identify if my engine is a 350 or 327? Engine block casting # 3970010 Vin stamped code 18l611487 thnaks, Julio Zamago 3970010 shows up on both 1968 327's and 1969-79 350's could be either originally. without disassembly no way to really know for sure.
It's a 4" bore block, so probably a 350. Less likely a 327 or 302. There are more characters stamped on a pad in front of the right head that provide additional information. You can write down that info and go to this website: http://www.nastyz28.com/decode.php
Look at your oil filter housing and see if there is a 010 or 020 stamped there. This will tell you that the block was made with an extra 1 percent tin and 2 percent nickel content. That means it's very desirable for a performance block.
this page will give year and model type and application for all chev blocks: -MorTec, Inc. Chevy Smallblock V-8 Casting Numbers List- copy and drop this on your browser, then choose - -CHEVY V-8 BLOCK AND HEAD casting numbers-
Facing the engine and to the right of center just below the intake manifold you will see a flat area about 1/2 inch wide and 2 inches wide. The numbers will be stamped on that area.
Yes, the serial number is stamped in ex: AH 23 10 2 and the part numbers are part of the casting, ex: 001 301 173
The block casting numbers are on the top driver side of the bellhousing flange at the back of the engine. The engine code is stamped into a pad on the block deck in front of the passenger side cylinder head.
1966 or 1968 327.