I started checking the numbers on my 1970 GTO Ram Air III to see what might still be original, only to find that the driver side head is a 12, and the passenger side is a 13. The motor has not been run since it was "rebuilt" a few years before I bought it. A carb is the only thing in my way before trying to start it, as it did not come with one. I just finished re-wiring the engine because it was a mess. My question is; could this set up even work? I have never heard of someone running two different heads. I do have a parts car with a 400 motor as well that has 6x heads. Maybe rebuilding those might be the safest way to go? I would hate to somehow ruin those other heads in case I can find the matching ram air head in the future. Any thoughts would be appreciated.
87 player bird said
Sep 17, 2010
There is another thread about this on a different board, seems the # was miss cased on that link, dunno about yours though. As long as the valves,guides, etc.. are the same, should not be a problem in my opinion. 1 head not close chamber, the other open chamber are they? Not too familier with BBP as I've only done 1 always been a bowtie guy. Mine the casting #'s were the same.
Goatboy said
Sep 17, 2010
Thanks, I'll check into it. I haven't even lifted the valve covers yet. I will check out that other thread. I guess anything is possible.
rabbit64cs said
Sep 17, 2010
Year(s)
Engine
Code 12
Intake
Exhaust
Volume
62-62
389/421SD
544127
2.02
1.76
68
70
400RAIII
12
2.11
1.77
72
Year(s)
Engine
Code 13
Intake
Exhaust
Volume
70
400
13
2.11
1.77
72
should be no problems here, you can check the date code on the heads ,the 12 will be a 70 head, 62 would not bolt up.
-- Edited by rabbit64cs on Friday 17th of September 2010 09:57:02 PM
pontorquer said
Sep 17, 2010
The 1970 Pontiac 400 head #12 and 13 are basically the same heads, I've seen 1975 Pontiac 400 6X head on one side and 5C on the other, same idea, I don't know why Pontiac did this on the assembly line, one of those mysteries ?
Highlander said
Sep 17, 2010
rabbit64cs wrotwhat i got
Year(s)
Engine
Code 13
Intake
Exhaust
Volume
70
400
13
2.11
1.77
72
should be no problems here, you can check the date code on the heads ,the 12 will be a 70 head, 62 would not bolt up.
-- Edited by rabbit64cs on Friday 17th of September 2010 09:57:02 PM
I have a set off late 60's Heads, the guy i got them from said they are 400 ram air Heads...how do i know for sure what i have?
Beaumont4008 said
Sep 17, 2010
Look at the casting number on the centre exhaust area as in fig 2. That number will identify the heads.
1-Certain heads, like this 1970 Ram Air IV, had the casting identification number on the end exhaust port. Still others would feature the number on the area just below the valve cover rail.
2-Most Pontiac cylinder heads feature an identification number cast into the external surface, which greatly simplifies identification. This number was usually the casting number, or a portion thereof. The area above the two center exhaust ports was a popular location for the casting numbers. 7F6 is the code for a 1972 455 H.O. head, while 13 is a 1970 330-horse (Firebird) or 350-horse (GTO) 400 head.
3-The head casting date is usually found on the exhaust side of the head just below the valve cover rail. These dates are read just like the block codes. The first letter identifies the month, the next one or two digits represent the day, while the last digit denotes the year the head was cast. C090 decodes as March 9, 1970 (this date code was taken from a 1970 #13 head).
Beaumont4008 said
Sep 17, 2010
Check out Wallace racing site for the list of casting numbers. See link below.
Thank you guys for all the information. I will just continue on towards getting this thing started. I will keep you posted on my progress.
Highlander said
Sep 17, 2010
Beaumont4008 wrote:
Look at the casting number on the centre exhaust area as in fig 2. That number will identify the heads.
1-Certain heads, like this 1970 Ram Air IV, had the casting identification number on the end exhaust port. Still others would feature the number on the area just below the valve cover rail.
2-Most Pontiac cylinder heads feature an identification number cast into the external surface, which greatly simplifies identification. This number was usually the casting number, or a portion thereof. The area above the two center exhaust ports was a popular location for the casting numbers. 7F6 is the code for a 1972 455 H.O. head, while 13 is a 1970 330-horse (Firebird) or 350-horse (GTO) 400 head.
3-The head casting date is usually found on the exhaust side of the head just below the valve cover rail. These dates are read just like the block codes. The first letter identifies the month, the next one or two digits represent the day, while the last digit denotes the year the head was cast. C090 decodes as March 9, 1970 (this date code was taken from a 1970 #13 head).
Thanks..I'll check that out tomorrow.
Highlander said
Sep 18, 2010
Highlander wrote:
Beaumont4008 wrote:
Look at the casting number on the centre exhaust area as in fig 2. That number will identify the heads.
1-Certain heads, like this 1970 Ram Air IV, had the casting identification number on the end exhaust port. Still others would feature the number on the area just below the valve cover rail.
2-Most Pontiac cylinder heads feature an identification number cast into the external surface, which greatly simplifies identification. This number was usually the casting number, or a portion thereof. The area above the two center exhaust ports was a popular location for the casting numbers. 7F6 is the code for a 1972 455 H.O. head, while 13 is a 1970 330-horse (Firebird) or 350-horse (GTO) 400 head.
3-The head casting date is usually found on the exhaust side of the head just below the valve cover rail. These dates are read just like the block codes. The first letter identifies the month, the next one or two digits represent the day, while the last digit denotes the year the head was cast. C090 decodes as March 9, 1970 (this date code was taken from a 1970 #13 head).
Thanks..I'll check that out tomorrow.
This is what i got..A8..
pontorquer said
Sep 18, 2010
Frank, Are you sure it's not 48 ie. 1969 Ram Air III heads ?
Highlander said
Sep 18, 2010
pontorquer wrote:
Frank, Are you sure it's not 48 ie. 1969 Ram Air III heads ?
I'll go check.
Highlander said
Sep 18, 2010
Highlander wrote:
pontorquer wrote:
Frank, Are you sure it's not 48 ie. 1969 Ram Air III heads ?
I'll go check.
Yep your right..it's a 4 not A..lol..
Beaumont4008 said
Sep 18, 2010
Highlander wrote:
Highlander wrote:
pontorquer wrote:
Frank, Are you sure it's not 48 ie. 1969 Ram Air III heads ?
I'll go check.
Yep your right..it's a 4 not A..lol..
Good set of heads 72 cc chamber will give you over 10-1 compression.
Highlander said
Sep 18, 2010
That's good too know.. was it originally on a 400.. how much hp would that make? Here's the head casting date..A309.
unburt said
Sep 18, 2010
The heads will work because of the chamber volume. They are identicle .
The #12 heads were used on manual tranny cars and #13 on auto equipped GTOs.
The heads were also used on 70 Grand Prix models.
Two years ago i ran #13s on my 400 and they work very well, but you have to pay attention to detonation because of the 10 plus compression.
Make sure your vacuum advance is set correctly and your total timing.
They work but your tune is important along with running good gas (octane)if you can get it.
Highlander said
Sep 18, 2010
Will they work on a 455 pontiac.
unburt said
Sep 18, 2010
Yes they will work on a 455 but the compression will be higher still with the icreased bore size and thats bad territory.
The only way to get them to work is if you are doing a rebuild and go to a dished piston to lower compression.
I am running 72cc eldebrocks on a 461 stroker but i have 20cc dish pistons to keep me at 10.3.
the70judge said
Sep 22, 2010
Usually its because someone needed a head so grabbed on that had the same cc's , I doubt Pontiac would do that and have a warranty issue
the70judge said
Sep 22, 2010
unburt wrote:
The heads will work because of the chamber volume. They are identicle . The #12 heads were used on manual tranny cars and #13 on auto equipped GTOs. The heads were also used on 70 Grand Prix models. Two years ago i ran #13s on my 400 and they work very well, but you have to pay attention to detonation because of the 10 plus compression. Make sure your vacuum advance is set correctly and your total timing. They work but your tune is important along with running good gas (octane)if you can get it.
# 12 heads are the 1970 Ram Air III heads for the Auto YZ block
lotsatas said
Sep 23, 2010
unburt wrote:
Two years ago i ran #13s on my 400 and they work very well, but you have to pay attention to detonation because of the 10 plus compression.
Very very special attention ...........I have learned that the hard way.
12
13
should be no problems here, you can check the date code on the heads ,the 12 will be a 70 head, 62 would not bolt up.
-- Edited by rabbit64cs on Friday 17th of September 2010 09:57:02 PM
Look at the casting number on the centre exhaust area as in fig 2. That number will identify the heads.
http://www.wallaceracing.com/head1.htm
Thanks..I'll check that out tomorrow.
Good set of heads 72 cc chamber will give you over 10-1 compression.