Need Help Decoding some BBC Chevy Heads and Block [Archive] - Chevelle Tech

: Need Help Decoding some BBC Chevy Heads and Block


thechevellekid
Jun 20th, 10, 9:03 PM
All,
I need some help in decoding some BBC Heads and Block I got for free.........

Here we go....................

The first set of heads (oval port)
-Pass 3931068 C18 9 GM3T
-Pass 2964290 D27 70 GM9T

What are they???

The next set of heads came with the block also (oval port)
-Pass 336781 J11 73 GM 11T
-Pass 336781 J10 73 GM 12T

The Block (454 2 bolt main)
casting # on rear of block - 3999289 GM T12 Pass HI PERF
number on deck T1012CWX 46448613

I think that the heads and block may be from a 1973 or 74 Chevelle / Monte Carlo 245 HP via the chevelle books I have. The HI PERF casting in the rear of the block is throwing me for a loop. The CWX code can also be for a 1972 454 270HP for a Corvette. I need some assistance in figuring out what I have here. :)

70-SS454
Jun 20th, 10, 10:48 PM
HEADS:

I think your first head is actually 3931063:

3931063 68-69 oval CLOSED 396, 402, 427, 101cc chamber Cast 3/18/69

3964290 69-70 oval CLOSED 396, 402, 427, 454, 101cc chamber, Large or small hex spark plugs* Cast 4/27/70

336781 73-85 Oval OPEN 454, 118cc chamber, 256/114cc ports Cast 10/10 & 11/73


BLOCK: (Same block I have)

3999289 454 71-79 2 or 4-bolt mains (Some "CE" replacement blocks had four bolt main caps) Cast in Tonawanda 10/12 (of the casting date year, which you didn't include, its on the opposite side of the rear of the block as the casting number where the trans/bell housing bolts) Need to to know the casting date to translate the CWX make/model indcator.

All Big Block passenger (including lt Trucks thru 1 ton) blocks got the "Hi Perf PASS" designation to my knowledge.

Hope this helps....

chrisstandring
Jun 21st, 10, 5:17 AM
One of the Village People must have been working at the foundry when my block was cast because it reads "Hi Perf Ass".

rodent4
Jun 21st, 10, 5:34 AM
One of the Village People must have been working at the foundry when my block was cast because it reads "Hi Perf Ass".

That's gold Jerry :D

thechevellekid
Jun 21st, 10, 9:00 AM
Frank....thanks alot!!! :thumbsup:

BTW, the casting date was pretty hard to read. I will need to look at it again tonight or tomorrow night to get it.