Senior Tech Team
Join Date: Feb 2006
Location: Lenexa (KC), Kansas
Re: Need Help Decoding some BBC Chevy Heads and Block
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....