The 4 or 6 digit casting number is found around the center exhaust side rocker arm cover bolt or among the rockers on really early heads [pre-68]. Really late heads have #'s like 4417 or such, they might be out closer to the top of the exhaust port. This number is also found on each side of the lower middle valve cover bolt, split into 3-n-3 on each side of that bolt. If it's an 1, 2, 3, or 4 head, look for the engine unit number/ID code as detailed in the
Small Block ID section. If no such ID is stamped in, then it's either an 1968 and later head, or a 1967 head from the left side of the engine. Check the other end of the other head.
Code:
ID/ Use Casting
Code Year(s) CID CCs Number Notes
1 '64 330 385101 Used ROCKER SHAFTS rather than
pairs on PEDESTALS.
2 '65 330 ?????? All V-8s now using PEDESTALS.
3 '66 330 60 389394
4 '67 330 60 394497
5 '68 - '69 350 64 397742 Excellent candidate for use today.
Good flowing, and high compression.
6 '70 350 64 403859 W-31's had larger 2.000 intakes. '69
W-31's?
7 '71 350 64 409147 W-31's had larger [2.000] valves.
7A '72 350 64 409147 The 'A' is a subscript, like ¼"
tall, to lower right of the '7',
like | 7A.
8 '73 - '76 350 79 411929 Smog heads. Have huge bb-sized 79cc
chambers yielding poor compression
ratios without extremes of
compensation.
10 '76, '77? 260? 57 550362
2A '76 - '81 260 554715 Easy way to ID a 260 engine.
3A '77 - '80 350 75 554716 1/2" bolt holes.
4A '77 - '79 403 83 554717 Matches the 4A or 4B block, get it?
Easy way to ID a 403. 1/2" bolt holes.
5A '80 - '84 307 64 3317
'85 also???
6A '85 - ?? 307 67 5844 Non-ECM Canadian cars?
7A '85 - '90 307 67 0142 This 'A', and the others from 2A to
6A, is a large capital letter equal
in size to, and immediately adjacent
to the 7, like | 7A.
D3A 350 3948 Diesel.
The OldsZone has some excellent pictures of where to look to see the casting numbers.
Small Block Head ID/Codes, Casting Numbers
