[Interceptor]

Found a 1970 Pontiac Grand Prix engine advertised locally with the following #s:

"--1970 Block Casting # 9799914, Block Code XH
--1970 Head Casting # 13 High Compression Ram Air III Heads
--1970 Intake # 9799068
--1970 Carb # 7040264"

#'s all check out to 1970, XH I believe is Grand Prix only, but I'm wondering if this might be a 4-bolt main RA block (9799914 w/#13 heads.). Any chance?

[Kenth]

No way.
It´s a Grand Prix XH engine as you already found.
Block may be drilled and tapped for 4-bolt caps but it uses 2-bolt caps.
And, #13 is not and has never been RamAir III heads, #12 is the 1970 RamAir III heads.

[steve25]

The number 13 head came on the 350 hp GP motors and are the same in function as the RA III 12 head!
The block is likely a 4 bolt and if you will be planing to build it up to 450 hp or more you should cut of six 1/2" course bolts and lock tight them down in those un-used bolts holes as leaving them open makes the mains prone to cracking!

[Kenth]

Originally Posted by steve25

The number 13 head came on the 350 hp GP motors and are the same in function as the RA III 12 head!

Yes, any D-port head functions the same..........only #13 has oilshields, larger combustion chambers, weaker valvesprings, shorter standard valves versus the #12 heads.

[steve25]

You sure about the bigger chambers and springs?
The big car motors if they where the of the highest hp optin always got the same set up as in the GTO !

[Kenth]

Yes, i have had enough of these heads on my bench to be sure.

And from 1970 Pontiac Performance brochure:

[Interceptor]

Look like press-in studs, big chambers, small valves. Number is 7B2.

[ponyakr]

"Number is 7B2."

The Wallace site doesn't show a 7B2 head. They look like '72 heads with no end holes.

I see a 7J2, which show to be '72 400 small valve 2-barrel heads. Could that be the number ?

I don't see any divider, making the d-port. Is this some sort of special Canadian head or something weird, that's not shown in most of the head ID lists ? Or did somebody hog out the center exhaust ports ?

[Kenth]

7B2 is a very early 1972 casting used only a very short time.
The open center exhaust did not work well so a revised series of heads, w/letters J, H, K, L and M were cast with the usual exhaust port style.

If my memory serves me right Pete McCarty wrote an article in Pontiac Enthusiast, "Mystery Heads", some 15-20 years ago?

[Interceptor]

Definitely 7B2

[Half-Inch Stud]

Is still funny to me that Heads like 13 & 16 is as Ram Air III, as a Q-JETs 7040262, 7040268 are as 7040263, 270, 273.

The (16s, 48s, 13s, 12s) Stamping indicates the calibration combo of little parts, not the casting features (sans air injection versions).

So I remain equally impressed to see 16s & 13s employed when the casting condition is excellent, and decidedly put to service.

[Steve C.]

Someday I'm going up into my attic and take a hard look at the numbers on my cylinder heads off my 1970 Trans Am 400 RAIII engine, the car came equipped with no air and automatic transmission. Other than a few tid bits removed from the engine compartment, headers and custom exhaust it was sold to me as numbers matching. I did confirm the block numbers and the VIN number. For year I thought the #12 d-port heads were on a stick car and the #13 d-port heads came on a automatic car. I swear on the center exhaust port there is a "3" and not a "2" cast in, but admit it is very hard to tell because of the cast material condition. Correct me guys is where the '12' or '13' was cast in, the center exhaust ports ? I know there are other numbers to look for clues but it has been years. I bought the car in 1988 !


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