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Discussion Starter · #1 ·
I've read a lot lately about how good the Pontiac iron intakes are. They have proven, in various tests, to out perform the popular Edelbrock Performer intake. And, they have run some mid 10's, on the strip, with 750cfm Q-jets, in legal Stock Eliminator class cars. So, I decided to start this thread, with info concerning the Pontiac iron Q-jet intakes.

No, I am not the ultimate authority, on the subject. :no But, I've gathered quite a bit of info and downloaded quite a few pics. So, I thought it would be a good idea to share some of that info and pics, in this thread. If any of ya'll see any of the facts I get wrong, PLEASE post your info, and help me get all the facts correct. THANKS ! :smile22:
 

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Well, the Q-jet was 1st used on a Pontiac V-8 in '67. So, that's the one we'll look at 1st. It's casting number is 978286, which is cast just in front of the carb mount. All the Pontiac iron Q-jet intakes are, of course, the dual plane type.

Many avoid the '67 intake, unless for a numbers matching build. The reason for this is a 1-year only deal. There are 2 holes connected by a small trough, all the way across the front, under the carb. Some call this a "hot slot", or a "smilely face" intake. The purpose was to use exhaust gas to heat the carb up quicker, when cold. But, it proved to transfer too much heat, and was discontinued, on all GM intakes within just a few years. I think the '67, is the only Pontiac intake with this feature. Most say that if you wanna use 1 of these intakes, you should plug these holes or in some way render them non-functional.

http://www.corvetteforum.com/forums/c1-and-c2-corvettes/1978466-q-jet-carb-base-gasket-tech-info-the-hot-slot-manifold-problem.htmlhttp://www.corvetteforum.com/forums/c1-and-c2-corvettes/1978466-q-jet-carb-base-gasket-tech-info-the-hot-slot-manifold-problem.html

http://cliffshighperformance.com/simplemachinesforum/index.php?topic=873.0

The '67 intake had a divorced choke mount on the passenger side, over the exhaust heat crossover. Pontiac used the divorced choke thru '72. The '67 400, with this intake and a 750 Q-jet, proved to make just as much power as the earlier GTO Tri-Power 389's.
 

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Don,I think the Fierbird 68 RA II cars in the FAST series has run low 10s.Dan Jensen Scott Tiemann prepared cars.Tom
Yeah, the quickest NHRA Pontiac Stocker I know of, running an Iron intake, is also a RA2 Bird, which belongs to Leo Glasbrenner. Not sure exactly how far below 10.50 he has run. Looks like he ran a 10.339 at Pomona.

http://www.dragracecentral.com/DRCStory.asp?ID=308213&Filter=Year2015#indextop

Anyhow, the stock iron intakes will definitely run down into the 9's, on the right engine, in the right car. There are probably several of the 9 sec GT cars that would still run high 9's with an iron intake. They are not the bad choke point that some have thought. :no
 

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Discussion Starter · #6 ·
The dual plane intake will always be the choke point on our pontiacs!Tom
Yeah, I don't think the iron Pontiac dual plane intake was made for racing and max high rpm performance. But, I think they are very efficient street/strip intakes, for good street manners and low rpm torque and power, especially on 400 and smaller engines. :yes
 

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Ok, for '68 Pontiac dropped the "hot slot". But it appears that the rest of the intake was basically unchanged. For the early part of the model year, the casting number was 9790140, for most of the 350's, 400's, & 428's.

Later in the year, which some refer to as "68 1/2", they used the same intake which was used in '69. It's casting number is 9794234. Haven't noticed a lot of difference in the two intakes. :no
 

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For 1970 the main change I can see is that there are no longer splits thru the 2 center bolt holes, on the passenger side. Not sure why the splits were use on the '67-'69 intakes, nor why they were discontinued for '70. Anybody know ?

The casting number is 9799068, for all 350, 400, & 455's which had an iron 4-barrel intake. And, the casting number was moved back to just in front of the carb, and the firing order back to the #1 runner.
 

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For '72, there is what I consider a major change. From '67 thru '71, the passenger side exhaust crossover hole was a large rectangular shape, while the hole on the driver side was a smaller square shape. For '72, the intake had the small square crossover holes on both sides.

This had to be done because in '72 Pontiac added a blind hole to their heads, just above the exhaust heat riser-to-intake crossover hole. This blind hole was used on thru the last 6x heads, on the '79 model 400's. Because of this blind hole, the large intake crossover hole, will not seal off the heat riser hole in the '72 and later heads, without modifications. Some say there are Fel-Pro gaskets that will make 'em work. But I looked at 'em, and would not recommend trying them. If some of you guys have successfully used 'em, for this purpose, please post your info.

There is an article which shows how to fill the passenger side blind hole with furnace cement, so that the '67-'71 intakes can be used with '72 & later heads.

http://www.hotrod.com/how-to/engine/hppp-1301-pontiac-cylinder-head-modification/

Because of this crossover hole change, I consider the '72 intake the best choice for any '72 and later heads. This is not based solely on the small hole, but also because in '73, as most of ya'll may know, Pontiac intakes had a big ugly EGR gizmo, hooked to the passenger side, just below the carb. :(

So, again, the '72 intake is my #1 choice, if using '72 up heads. The casting number is 485912.

Now, if you don't wanna use the exhaust crossover, you can just remove it from any '67-'71 intake and make plates to cover the heat riser holes. Lots of us have used these type plates when running a factory alum RA4 or 455HO intake, without crossover.
 

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Well, as mentioned, the '73 intakes had the EGR valve hooked to 'em. Pontiac also switched from the divorced choke to the "hot air" choke. So, the '73 intake marked a major change. :(

And there are at least 3 different casting numbers shown for '73 intakes.
 

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Discussion Starter · #13 ·
Not much change in '74, but in '75 they got the ugly top, which used a stainless metal plate, under the carb.

Only 2 more after that. The '76-'77 were the same, and the '78-'79 were the same.
 

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Sorry for having to stop, before I got all the intake info posted. We are almost out of data usage on our Verizon hotspot. So, I'm having to spend the remainder of our monthly pay period, posting from the library in a nearby town. And yesterday, we were out of town, so I didn't get to go online. :(

Anyhow, I'm back. So, I'll try to post some more intake info that might help somebody down the road.

One thing I've noticed is that some of these 40 year old parts are really rusty, when you find 'em. But, the iron intakes are thick enuff so that they can usually be sand blasted(or whatever) and cleaned up so that they will work just fine.

Sometimes the rust is so bad, you can't even make out the part number and/or date code. Same with some heads. So, just in case somebody who reads this might someday run across a rusty iron intake, which they can not identify, I'll point out some things that might help make a positive ID.

For the '67 intake, it's easy. Look for the "hot slot" or "smiley face" groove, just in front of the primary holes. :smile22:
 

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For '68 there is no longer a "Hot Slot". Also, if you look just in front of the carb mount, on the '67, you'll notice that there is a cast ridge going along the #2 runner. At the end of the ridge, there is a round pad, which has a hole in it. I assume this hole is for a vacuum fitting.

Now, if you look at the '68 intake, you'll notice that there is no ridge on the runner, and no hole in that location. Instead, the hole is almost directly in the center, in front of the carb mount. And it appears that there is a special pad cast for the hole, which was not present on the '67 intake. I assume this hole is for the PCV hose fitting.

The next intake which was used in late '68 & 69, does not appear, to me, to have any major significant changes, other than the cast numbers & letters, which would allow you to tell the difference between it and the early '68 intake. It's minor, but it appears that the vac fitting hole in the #1 runner is quite a bit larger in the later intake. It even appears to be larger than the PCV fitting hole. So, I suppose this is one way you could ID the two. If some of ya'll know of any other differences, please post that info. :smile22:
 

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It's easy to tell the difference in the '70 intake, compared to the '68-'69's. The passenger side flange on the '67-'69's had a split thru the 2 center bolt holes, + some large openings below the splits. In '70, the flange was solid--no splits--no openings. Otherwise, it looks to me to be almost identical to the '69 intake. Can ya'll spot any other differences ? :smile22:
 

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OK, for '71 there was a change, which makes 'em easy to ID. The divorced choke mounting pad was changed, from previous years. It was completely flat. And the choke itself was different, with the attaching holes in a different location than in previous years. The new pad had 2 holes. It appears that one hole was threaded, for the hold down bolt, and the other hole was for the choke locating stud(or whatever it's called). The last pic below, shows a typical '71-'72 choke.

And, the '71 still had the large rectangular exhaust heat crossover hole, under the choke pad. So, the '71 intake was definitely a 1 year only model. :smile22:
 

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The '72 intake was also a one year wonder. As I mentioned in post #11, '72 was the 1st year the Q-jet intake had a small square exhaust heat crossover hole on the passenger side. Aside from that, it looked very similar to the '71 intake.

One other difference I've noticed is on the water crossover. In '72 there is still a pad for a hole, on the driver side of the crossover. But, of the several pics I've found, I have not seen a single pad which had a hole in it. In previous years, even if the hole had a plug in it, at least the hole was drilled and tapped. So, I assume that it is possible that the '71 was the last year which had a hole on that side. :smile22:
 

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Then, as mentioned, '73 brought some major changes to the intake. They had a big EGR valve attached to the passenger side, below the carb. They also no longer had a divorced choke. Instead there was a "hot air" choke attached to the side of the carb. And plumbing to the choke went down through a plate, which covered a hole in the heat crossover.

Another bad thing about the '73 intakes was the big sump under 'em. These had 3 big pipe plugs in 'em and required a different valley cover, which had a deep depression in it, for the sump. With all the hardware and plumbing attached, these intakes were heavy and ugly. But, it has been proven that they flow just about as well as the earlier intakes.

As, mentioned there were at least 3 different casting numbers, in '73. All these, plus the '74's looked to be very similar. And they all still had the flat carb mounting pad, like the '68-'72 models. So, with this info, the '73-'74 series of intakes should be easy to ID, even without any numbers. :smile22:
 

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The '75 is also easy to ID. It not only was the 1st year to have the ugly carb mount pad, which used a stainless plate under the carb, but it had 4 round pads in front--two on the water crossover, one over #1 runner, and one over # 2 runner. These 4 pads had no holes in 'em. So, there is no way to get the '75 confused with any other year. :smile22:
 

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