TAC Tech => Mechanical => Topic started by: BlueBaron762x39 on August 27, 2021, 11:34:28 PM
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Looking at the shape of the dualjet carburetor I'm not sure this would be possible. I recently bought a base model 1979 Firebird with a Pontiac 301 engine. It appears to have the factory dualjet carburetor. Will a factory 1979 shaker scoop system be able to mount to the top of it some way? I know the 1979 Trans Ams with Pontiac 301s had shakers but they were placed on quadrajet carburetors on the Trans Ams.
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Assuming a dualjet is 2v carb., the answer would be no (at least that how it is for 350, 400 and 455, don't know much about 301s).
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It’s literally just the front half of a quadrajet. If you have a welder, you can run cut/fit a piece of metal to fill in the area of a 4 barrel air cleaner.
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^^^ that, would improve performance as well.
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I ran a shaker on a 2V carb on my car for about 10 years. The shaker fit on the 2V filter base and I used a chrome aftermarket filter top. This was on a '70 so fit on the later filter bases may be different.
My '70 Esprit originally had a 350 2v and since it had low mileage on it I figured I'd just leave it stock and run it while I did a lot of other work to the car. I planned on leaving it as an Esprit, painting it and just using it as a daily driver. While doing the bodywork a friend convinced me to swap all the TA body parts on the car, which of course he happened to have available since he was parting 2nd gen Firebirds at the time. So I needed to figure out what to do about the shaker, turned out to be pretty easy.
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Like Jon said the dual jet is essentially the front end of a quadrajet. I personally would go with Wellington’s suggestion of finding a donor 301 with a four barrel intake and quadrajet. If you can find one from a 1979 or 1980 Trans Am with the air cleaner and shaker it would be that much better. Especially if you can get the hood with cutout. Then you would have all the parts the factory used and would be assured everything will fit correctly. Keep in mind some 1980 301’s and all 1981’s had an ECU controlling the Carb, you want to stay away from those. Also, the 301 makes most of its power at low rpms, so adding a quadrajet won’t boost performance very much.
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Because the air cleaner mounting pad on the air horn dual jet is the same radius as the QJ, (but only runs about 180° at the frt,), I don't see why the shaker AC base wouldn't drop right on. The only problem is it would be open on the back side, and maybe not be too stable. But why wouldn't the AC stud hold it to the carb. tight? Worth a shot. In time, I would up-grade to a QJ anyway.
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I ran a shaker on a 2V carb on my car for about 10 years. The shaker fit on the 2V filter base and I used a chrome aftermarket filter top. This was on a '70 so fit on the later filter bases may be different.
My '70 Esprit originally had a 350 2v and since it had low mileage on it I figured I'd just leave it stock and run it while I did a lot of other work to the car. I planned on leaving it as an Esprit, painting it and just using it as a daily driver. While doing the bodywork a friend convinced me to swap all the TA body parts on the car, which of course he happened to have available since he was parting 2nd gen Firebirds at the time. So I needed to figure out what to do about the shaker, turned out to be pretty easy.
That's basically what I'm looking at doing with this 1979 Firebird (using it as a daily driver). When I get the car back from the repair shop I think I'll see if this shaker will attach to the filter base like you mentioned you did with your 1970. That might work for now. Will converting it from a dualjet to a quadrajet affect the performance that much? From what I've read online so far, it doesn't look like the quadrajet equipped 301s had much more horsepower than the dualjet equipped ones.
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Once the QJ is tuned properly for the 301, it'll be a noticeable improvement. Not only in acceleration, but the visual and sound appeal will be worth the investment.
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I agree with Tajoe, nothing beats the sound of those large secondaries opening up on a quadrajet.
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Do any of you know what the correct dualjet carb number is for a 1979 301? Thought it'd be a good idea to check and see if the dualjet that's on the car now is actually the correct one.
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So this is what Pete McCarthy lists...
135HP dual-jet# 17059160
150HP Q-jet#s -17059271, (stick shift), or 17059272 auto.