Author Topic: Duel Power Piston  (Read 1394 times)

Offline lightning boy

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Duel Power Piston
« on: July 28, 2022, 05:12:41 AM »
I have a Qjet from a 74 Pontiac that has the aneroid valve in the front with two power pistons. One controlling the primary metering rods, and another controlling an additional rod.
I have never worked on one of these before. What were they for and can they be modified for street use?

Offline Cliff Ruggles

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Re: Duel Power Piston
« Reply #1 on: July 29, 2022, 01:30:29 AM »
Pontiac carburetors didn't use that arrangement.

What is the carburetor part number?

Offline lightning boy

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Re: Duel Power Piston
« Reply #2 on: August 01, 2022, 05:02:22 AM »
It's a 7045184

Offline Cliff Ruggles

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Re: Duel Power Piston
« Reply #3 on: August 03, 2022, 02:39:20 AM »
Without taking the time to look it up I'm pretty sure that's an Oldsmobile Q-jet, not one from a Pontiac engine.....

Offline Burd

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Re: Duel Power Piston
« Reply #4 on: August 05, 2022, 08:57:26 AM »
My carb booth says Old’s, 1975, 455, w/ AC, delta, cutlass, ambulance, and hearse or Hurst for the dummy’s that say that. 
1978 YEE
1995 Q45
F ire
B irds

Offline quadrajam

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Re: Duel Power Piston
« Reply #5 on: August 05, 2022, 10:33:23 AM »
A long long time ago I tackled one of these. I had to convert it to conventional
metering rod setup and it actually ran well. The problem was that it had multiple
primary well plugs and leaked so bad I scrapped it for parts. Instead of aneroid
they should call it hemorrhoid because it was a PIA.
Can be done though.

Offline Cliff Ruggles

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Re: Duel Power Piston
« Reply #6 on: August 07, 2022, 05:22:46 AM »
With some work you can convert them to the later style APT but this does NOT correct the fundamental flaws with the design.

I recommend in most cases to move to a later unit in the first place.

The only time I'll tackle one of those variety is when it's a numbers matching restoration and even then I try to stay clear of them.....

Offline lightning boy

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Re: Duel Power Piston
« Reply #7 on: August 08, 2022, 01:51:48 PM »
Okay, thanks guys, I'll use it for parts.
What were they for? and what are the flaws?
Just trying to learn something.

Offline Cliff Ruggles

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Re: Duel Power Piston
« Reply #8 on: August 09, 2022, 05:11:13 AM »
The flaws are many and too lengthy to go into great detail.

Right to start with that APT simply puts fuel under the jets, so fattens it up everywhere. 

The flow path from the APT jet/rod is unequal in length.

The flow path requires a common connection between both jets.

ALL of it is at the bottom of the carburetor where all the water, dirt and debris would go.

That's the short version.........