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Author Topic: Trans Am vs Formula intake manifolds - are they different?  (Read 3532 times)

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lessasdragon

  • Message Board Member not current NFTAC Club Member
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  • Posts: 4
Trans Am vs Formula intake manifolds - are they different?
« on: August 15, 2007, 11:23:22 AM »
I recently replaced my Formula's carburetor with a new one. The old one was warped on the bottom and could not be sealed, a spacer had to be installed for the linkage to clear the intake manifold.  I have a '76 Trans Am engine in my '78 Formula, the new carburetor is the same as the old one except for the 1 inch spacer for the Rochester stock carburetor.  Now the hood will not close, what is the problem? Does the Trans Am have a higher intake? Could it be the engine mounts? Apparently whoever installed the previous carburetor just bolted it directly down on the intake? Suggestions please or where to look for information?
« Last Edit: August 15, 2007, 11:47:13 AM by firebirdclub »

Todd Stahr

  • Firebird & Trans Am Club Tech Staff
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Re: Trans Am vs Formula intake manifolds - are they different?
« Reply #1 on: August 19, 2007, 12:52:08 PM »
2nd gen birds have a very low hoodline, the 70-75 Formula hoods have it the worst. The stock airfilter housing will not fit with a 1 inch spacer under any carb. It is just too tight in there.

The mounts for your 78 wont fit the 76 chassis, but the block has the provisions for both, so its probably not anything to do with them. :)

All Pontiac intake manifolds for D port heads are pretty much the same from 1967-1972, there are some differences but they are relatively minor. The later EGR manifolds have the same height for the carb flange as the early manifolds, but they are different in the internal passages.

Aftermarket intakes have the carb flange at different heights, Edelbrock's Performer is quite similar to the stock intake, if your engine has a Performer RPM, Torker II, or other Weiand single plane intake, the carb will be sitting too far up for the factory air filter.

My 79 Formula had a Torker II with an 850 Holley, 1/2" spacer, and a drop base Moroso air filter. To close the hood I had to adjust the hinges so the rear edge of the hood was raised as far as possible. The pic attached shows what I mean. That is the only way the stock hood would fit with that carb and intake. A 1 inch spacer would have needed a shaker from a Trans AM modified to fit, or bolted to the hood for clearance, or come kind of aftermarket hood like the cowl induction that I put on it later to clear the Victor and 1050 Dominator.

If you need a spacer to mount a Qjet, then you either have an aftermarket intake, or you have a 65-66 intake that had the carter 4 barrel on it. The Qjet intake is a better piece than the older intakes were. If you have an aftermarket aluminum intake, and your engine is relatively stock with a cam under 240 degrees duration at .050 lift then the stock intake should work best for it, with a well built Qjet carb.
Performance and general repair tech. Traditional Pontiac V8 is my specialty, as well as automatic transmission repair/diagonossis. 2nd gen speciality, and with the addition of the 98 Formula 4th gen LS1 I am getting to know them real well. Holley and Qjet advice as well.

Chalk mark restoration and date codes arent my thing. W.O.T. is my thing..

Is it strange to have 9 firebirds?

lessasdragon

  • Message Board Member not current NFTAC Club Member
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  • Posts: 4
Re: Trans Am vs Formula intake manifolds - are they different?
« Reply #2 on: August 22, 2007, 11:11:46 AM »
Thanks so much for the reply you seem to know more than what I have found in research and in the tech manuals, after a lot of research we have found this engine was manufactured in 1968, as far as everything else it has remained stock from the factory we have ordered a new airfilter to lower it another 1/2 inch and if it still will not close we are going to replace the spacer with a 1/2 inch one, we have to have something there to allow all the mechanisms to work on the carb...

2nd gen birds have a very low hoodline, the 70-75 Formula hoods have it the worst. The stock airfilter housing will not fit with a 1 inch spacer under any carb. It is just too tight in there.

The mounts for your 78 wont fit the 76 chassis, but the block has the provisions for both, so its probably not anything to do with them. :)

All Pontiac intake manifolds for D port heads are pretty much the same from 1967-1972, there are some differences but they are relatively minor. The later EGR manifolds have the same height for the carb flange as the early manifolds, but they are different in the internal passages.

Aftermarket intakes have the carb flange at different heights, Edelbrock's Performer is quite similar to the stock intake, if your engine has a Performer RPM, Torker II, or other Weiand single plane intake, the carb will be sitting too far up for the factory air filter.

My 79 Formula had a Torker II with an 850 Holley, 1/2" spacer, and a drop base Moroso air filter. To close the hood I had to adjust the hinges so the rear edge of the hood was raised as far as possible. The pic attached shows what I mean. That is the only way the stock hood would fit with that carb and intake. A 1 inch spacer would have needed a shaker from a Trans AM modified to fit, or bolted to the hood for clearance, or come kind of aftermarket hood like the cowl induction that I put on it later to clear the Victor and 1050 Dominator.

If you need a spacer to mount a Qjet, then you either have an aftermarket intake, or you have a 65-66 intake that had the carter 4 barrel on it. The Qjet intake is a better piece than the older intakes were. If you have an aftermarket aluminum intake, and your engine is relatively stock with a cam under 240 degrees duration at .050 lift then the stock intake should work best for it, with a well built Qjet carb.

National Firebird and Trans Am Club Message Board

Re: Trans Am vs Formula intake manifolds - are they different?
« Reply #2 on: August 22, 2007, 11:11:46 AM »


 

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