help with engine numbers
Thread Starter
Safety Car
Joined: May 2005
Posts: 4,176
Likes: 7
From: Jennings LA
help with engine numbers
here are some numbers off of my 454 in my 71. I know the block is not original but it looks like the heads and intake may be.
head #'s GM12T
H27-70 (date code?)
3993820
the numbers are the same on both heads
intake #'s GMT
H26-70 (date code?)
3955287
block #'s GMT7
the block has HI PERF stamped on the back of the block passenger side
OK what do I have, are theese heads any good?
head #'s GM12T
H27-70 (date code?)
3993820
the numbers are the same on both heads
intake #'s GMT
H26-70 (date code?)
3955287
block #'s GMT7
the block has HI PERF stamped on the back of the block passenger side
OK what do I have, are theese heads any good?
Instructor
Joined: Jun 2003
Posts: 182
Likes: 0
From: Clinton Indiana
Hope This Helps..........
Per "Chevymania".........
#3993820 - 402/454 71 2.06/1.77 113cc Oval port
#3955287 - 402/454 70-71 Q-jet Oval port LS-3/LS-5
Ya' got anymore block numbers, besides the GMT7???
#3993820 - 402/454 71 2.06/1.77 113cc Oval port
#3955287 - 402/454 70-71 Q-jet Oval port LS-3/LS-5
Ya' got anymore block numbers, besides the GMT7???
Le Mans Master
Joined: Feb 2006
Posts: 7,582
Likes: 1
From: In The Hardwoods Up North
I'd say the 820s are the best oval/open port heads
edit: and with the 2.19 1.88 valves make more horsepower than rectangle ports
edit: and with the 2.19 1.88 valves make more horsepower than rectangle ports
Last edited by 78SA; Feb 15, 2006 at 10:45 AM.
Thread Starter
Safety Car
Joined: May 2005
Posts: 4,176
Likes: 7
From: Jennings LA
Originally Posted by djgrelli
Heads are correct for your year 3993820 454ci, 365hp
Block is correct also for your year 3963512 454ci 365hp,425hp.
Block is correct also for your year 3963512 454ci 365hp,425hp.
the block must have been changed early in its life. I know for sure it has had that engine for the past 25 years
