1969 RAM AIR III heads - Pontiac GTO Forum
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post #1 of 45 (permalink) Old 01-24-2014, 09:32 PM Thread Starter
 
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1969 RAM AIR III heads

Hey guys, I have a question about heads...specifically '69 RAM AIR III heads. First, are '69 RAM AIR III heads good heads to use? I understand aluminum heads are better, but there is a local guy selling a set for $450. Second, do I necessarily need the full RAM AIR set up in order to benefit from using RAM AIR III heads? Lastly, will after market headers work well with RAM AIR III heads or should I use stock RAM AIR exhaust manifolds?

Any advice would be appreciated. Thanks.
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post #2 of 45 (permalink) Old 01-24-2014, 10:06 PM
 
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Not an expert. I just like to read a lot. I'm pretty sure the RAIII heads were no different than any of the other D-port, small chambered (72cc), big valve (2.11/1.77) heads from 68-70. They are all desireable, but have the same specs. Maybe there is a difference in flow, but someone with hands on experience could answer that better than me.

I've also read a lot that the RA exhaust manifolds fit and seal better with only a slight loss of power compared to headers.
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post #3 of 45 (permalink) Old 01-25-2014, 06:34 PM
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^^^^^this. Good heads, but you must use dished pistons to use them with today's poor fuel. If you just bolt them on, you will be stuck using race fuel. Too much compression. The RA manifolds are superior to tubing headers for a street/strip car in every way.
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post #4 of 45 (permalink) Old 01-25-2014, 08:26 PM
 
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OK. Now, I'm more than curious. Would someone please explain the difference between Ram Air III heads and.. say the standard heads you take out of a 400 GTO or Lemans, without Ram Air. I was interested in Ram Air heads when I rebuilt my GTO 400 and a buddy of mine... very knowledgeable about Pontiac engines, I might add sold me a set of nice clean heads for $350, that I rebuilt and used for my project. He said the Ram Air heads weren't worth wasting my time looking for. Besides, he said I'd pay an arm and a leg just to get them and they would not add 13 HP like I had been told in performance when engaging a Ram Air system. He did say something about the fuel of today, vs the fuel of yesterday. Sure it was all about the lead content... back then compared to the crap we're burning now.

So. With that been said should we all be burning Premium (91 or better octane) be a better choice? It would be nice if someone would give us a quick or somewhat detailed education here. My engines not running yet, but soon will.
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post #5 of 45 (permalink) Old 01-25-2014, 09:51 PM Thread Starter
 
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Well I was able to pick up the RAM AIR III heads for the low price of $400. They are complete, but could use cleaning and likely a good rebuild (or at least a valve job and new valve guides).

Geeteeohguy, thanks for the heads up on use on the heads. Before I use them, I likely to need to rebuild engine and heads. The heads are #48 heads, whereas my current heads are 7K3 heads.

Besides the pistons and RA manifolds, what else do I need to get the benefit of these heads?
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post #6 of 45 (permalink) Old 01-25-2014, 11:37 PM
 
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Rvp986, RAIII engines used the same D-port heads as on other engines. The difference was the cam and fresh air intakes. The RAIV, 455HO, 455SD had round port heads which flowed much better and are very rare.
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post #7 of 45 (permalink) Old 01-27-2014, 11:46 AM Thread Starter
 
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So in short, if I do not have a Ram Air engine block (meaning the cam and/or pistons), is there any advantage to using RAIII heads (72 cc chambers) over the 7K3 heads (96 cc chambers)? With 91 Octane fuel as being the best here in California, will RAIII heads (with RA exhaust manifolds) perform any better than the 7K3 heads I currently have?

I have also noticed that the casting number "48" is used on both 1969 RAIII heads for the 400 as well as non-RA heads for the 350. How do I verify that these heads are RAIII heads? Also, looking up on a chart of Pontiac heads, I see that the #48 RAIII heads are for a Manual transmission. I am running a TH400 automatic tranny, is this going to be a problem?

Last edited by mrvandermey; 01-27-2014 at 01:03 PM.
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post #8 of 45 (permalink) Old 01-27-2014, 03:24 PM
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Having or not having a Ram Air block has nothing to do with how well the heads work to make power. The crank/pistons/rods make up what is called the "rotating assembly" and are not considered part of the block. The rotating assembly contributes to power output because the combination of bore/stroke defines the swept air volume - cubic inch displacement. The parts are installed into the block. It can be a little confusing because the combination of engine block and rotating assembly is what is referred to as a "short block".

Likewise the cam shaft - not part of the block. The cam, lifters, pushrods, rockers, and valves collectively make up the "valve train". The heads plus valve train make up what is called the "top end" of the engine and is also the second primary determinant of power output because these parts determine peak volumetric efficiency (how much of the swept volume the engine can actually use) and also the rpm where peak VE occurs.


As already noted, RA III's are pretty much the same as any other D-port, large valve head. Do NOT try to run these with flat-top pistons on a factory spec engine even with 93 octane, let alone 91. You might as well take a hammer and knock holes in the tops of all your pistons before you even assemble the engine and save it the trouble of doing it for you.

To use them with 91 octane, you'll need pistons with at least 15 cc's of dish volume in the tops, assuming everything else is nominal.

With the 7K3's, you have the opposite problem. ASSUMING that they are actually 96 cc's (they may have been milled, and also untouched heads can vary quite a bit from the published specs), you'll be at 8.144:1 on a factory nominal 400 bored +0.030, lower if it hasn't been bored. IF the heads are 96 cc's and IF they've never been milled, you could mill about .045 off them and get close to 86 cc's, which - along with zero-decking the block - would put you at 9.150:1. But before you start cutting on anything, make sure you measure everything, all the chamber volumes, piston deck clearance, head gasket compressed thickness and gasket bore size - first. Also, milling the heads that much is a one-way street. If you ever need to rebuild the engine in the future and have the heads "decked" to make sure they're flat, there won't be able to without leaving that surface too thin to use.

As far as ID'ing the heads. On any piece of Pontiac cast iron, always start with the 4 character date code FIRST - to determine the model year of the part. Then you can use the casting code to ID it correctly. (If they're model year 1969 with casting code 48, then they're both 350 heads AND RA III heads - it was the same head.)

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post #9 of 45 (permalink) Old 01-27-2014, 04:31 PM
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What Bear said, in spades. Me, I'd be measuring those 96cc heads and plan on milling them (and possibly the intake) to work on your block for about a 9-ish CR. I have a nice set of Ram Air heads, #12, sitting on the shelf because they are ping monsters on my '67, and that was with 94 octane fuel at the time. Running 87cc #15 heads now, and it's still marginal on a 100 degree day with 91 octane. Rule of thumb, to figure out what octane is needed with compression ratio: 8.7:1 needs 87 octane, 9.0:1 needs 90-91 octane, 10:1 needs 100 octane, etc. With today's pump gas , you are limited to a bit over 9:1 CR with iron heads.
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post #10 of 45 (permalink) Old 01-27-2014, 04:34 PM Thread Starter
 
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I am so glad I am not deep into these heads. I am about $400 into them (a trade for a endura bumper). Well, I may just flip them to some one else. I truly wish I could afford a proper engine build and just go out and buy a set of new aluminum heads. But that simply is not in my budget right now.

Now I see why folks just opt to drop in a LS1/2/6.....seems like it might be easier. This is one of those times I am having information overload. All roads seem to be coming back to an expensive rebuild, or just buying a turn key car. The good news is I can easily sell these RAIII heads. From what I am understanding, RAIII heads are the worst of the RA heads, do not make much difference, and these particular ones, are the least desirable of them all. I guess it is time to dump them.
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