I found a set of 13 heads today while going through a bunch of pontiac parts a guy has for sale, they should be a 70 RA III but instead of the raised numbers on the exhaust port the numbers are stamped, a 1 on one side and a 3 on the other doesn't appear to be ground off and stamped, never seen this before and was wondering if anyone has an idea before I buy them. He also has a 64 421 HO short block he's looking for a price on, any thoughts

Jerry,

Often, a "reject" from one "line" would be restamped more "accurately" (like a 12 with too much chamber volume COULD become"13"). It' unusual, but not unheard of.

13s are not "Ram Air" heads. NO "d-port" head is, as ALL of them were used in non-Ram Air applications. Please reserve the name "Ram Air head" for small-chambered "round port" heads.

These heads will require a rather large "dish" in the piston for using 93 octane gas. Static compression is WAY too high with flat-tops.

Jim

70-RAIII(d-port) m/t FB's and GTO's used #12's.
With a/c #13's.
Some auto's w/o a/c got 13's too.

I've read this before too. However, this has also been a point of confusion to me as per Mr Pbody's post I also thought RA II and on were round port only.

Briefly...

The term RA originated in 67 with the d-port exhuast and continued till bout mid 68 when the RAII o-port exhuast heads came out.
In 69 Pontiac made slight engine/head changes and changed the terms to RAIII(d-ports) and RAIV(o-ports) which continued thru 70.
Every year both style of heads had different casting #'s.
BTY, Pontiac never listed RAI's in 67 or 68 even though they had a 1st and 2nd design 67(closed chamber), and different casting starting in 68(open chamber). Just called them RA.

Clear as mud right?

Dont even get me started on H.O.'s

Hmmm, I'm 50 and there is so much to learn and so little time!

The funny thing is that all the Ram Air hoopla was marketing. Isn't the term "ram air" meant the means of forcing air into a desired location in order to improve fuel air mixture and gain horsepower/torque? Scoops are cool no matter what the outcome. Bragging rights to "these scoops are functional" is so much better. I know someone will correct me but this is my understanding on the whole matter.

Actually, the fist reference to "Ram Air" was for the '65 TriPower GTOs. A "Ram Air" pan was made available "over the counter". The only truly effective versions (according to "lore") are the "reverse" scoops like on T/A (shaker) and the '71-'72 GTO and Firebird "Formula" scoops, which stick out in front, into the "air flow". The rest simply offer "ambient air" for the carb, making it a bit more efficient at mixing the fuel for performance.

The "Ram AIr" engines were far more than a simple "open scoop". Different heads, cams, intakes, exchaust, carb (calibration), distributor curves, etc. By '69, a Ram AIr GTO was again, a "force to reckon with" in the muscle car arena. Ever notice when they "test" muscle cars, they ALWAYS use a 400 GTO against the 454 Chevelle, 455 Olds and Buick, 429 Ford, 440 Dodge (or even Hemi), etc.? They put a "boy" in a man's world, and he did okay, actually... Imagine had they produced a 428 Ram Air IV!!! Or even just PRODUCED Ram Air V...

I object to using the term "Ram Air head" for d-ports because, while they WERE used on the lower Ram Air engines, the same heads were also used on other "non-Ram Air" engines. The best/easiest way to avoid the "confusion" is to restrict the use of the term for the "special" stuff unique to Ram Air engines.

FWIW

Jim

Makes sense to me. Any way to avoid further confusion.
Now if we could just decide whether it should be called a RA car with out open air or an HO instead, that would be good too.

I would agree on the std. 16, 12, 13, 62, 48 head issue that every ebay seller claims RA status, but would disagree that all D port heads can’t be called a RA head.

The late 67 – “97” head and the 68 “31” head was unique to the GTO/FB RA option. Both are D port, but were not installed in any other size or HP rated engine. I would elevate them to RA level. (And the price when they do pop up reflects it)

To me when looking at engine options from the day. I see perfomance mods to make more power and increase performance. Ram Air terms in regards to pontiac was just there little niche. I believe later in production the did make cars ram air IE; 70-73 formulas. But we have talked that the functional scoops on early birds done very little for performance. Any head modification improves performance. Basically they put racing mods on stock cars from the day and did a word play to inhance sells.

I can agree to point.
The exhuast port didnt "really" make'm much better. It was the intake port.
Valve head size is the same except IV's where taller, tulip shaped heads, with taller/stronger springs and 1.65 rockers.
Strange they ran no better then 68 RAII's with 1.52's.
67-70 RA/RAII/H.O. d-ports did use stronger springs vs standard d-ports.
068/744 cams.
Also better exhuast man's just like the o-ports.
And of course different curved distrib's/jetting in carbs.

I got the cam out of the block tonight it is stamped 066,not even a 1970 number must have been changed at some point, still havent decided if Im going with the 670's or the 13's for heads yet, may get both rebuilt since there just laying around anyway