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alum cylinder heads

961 views 4 replies 4 participants last post by  1971ls6 
#1 ·
I have a set of alum heads #3946074 where do I find the date code all I can find is the casting # and a number on the inside that looks like casting tag with the number 12345 ? does anybody know what that means
 
#3 ·
Even if they are over the counter heads,as long as they are 074’s, they are desirable for the few select cars that came with them. These heads have porosity issues and break rocker arm pedestals, drop valve guides and pull the studs out.

Do they have any welds?
 
#4 ·
Listed as a single application,

3946074,

1969 Camaro, 427, 430 h/p. (ZL1)
1969 Corvette, 427, 430 (L88), 430 (ZL1)
1971 Corvette, 454, 425 h/p (LS6),

2.190/1.88, 118.00 cc.

With these notes:

1969: "This aluminum head was a totally new design for the 1969 L88 Corvette and is an open chamber design. The head is similar to #3904392. This cylinder head has a round exhaust port instead of the eonventional high performance square port design because this head uses a 12.50 compression ratio. - This head was also used in 1971"

1971: "This aluminum cylinder head was a totally new design for the 1969 L88 Corvette, The head is similar to #3904392. This cylinder head has a round exhaust port instead of the conventional high performance square port design. - This head was used in 1969"

Date code is just below casting number, and should have a letter, and numbers, as such, Example: D276, D - April - 27 day, 6 - 1966
'
 
#5 ·
71 LS6 ran these heads with 9.5 compression. All of the heads I have seen have the date code on the underside.

A lot of these heads ended up in boats back in the day. 80#’s is a lot in a small drag boat
 
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