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61
Quadrajet Carb Talk and Tips / Re: Need some help and parts for my 17058213 Build for my Big10 Truck from 1978
« Last post by Kent on January 28, 2026, 03:19:30 PM »
Another question I have read at Hemmings or somewhere there are modified Accelerator Check Valves you can buy from mikes carbs parts WA and special squirter from quadrajet parts NJ what is going on with these special parts?
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Quadrajet Carb Talk and Tips / Re: Need some help and parts for my 17058213 Build for my Big10 Truck from 1978
« Last post by Kent on January 25, 2026, 01:16:12 AM »
Is Cliff not reading here?
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Quadrajet Parts and Numbers / Re: Carb 17057258
« Last post by Hojs69 on January 24, 2026, 02:06:16 PM »
I do have the book. Thanks for the reply.

Took it apart yesterday and it appears to be "stock." Ordering a kit and a few upgrades next week.
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Quadrajet Parts and Numbers / Re: Carb 17057258
« Last post by Kenth on January 24, 2026, 08:56:23 AM »
Looks like a nice unmolested unit.
Be sure to order Cliff´s book on Quadrajets, if you don´t already have it.
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Quadrajet Carb Talk and Tips / Re: Opinions on these "custom-50m-metering-rods"
« Last post by Kenth on January 24, 2026, 08:46:05 AM »
Here are the specifications on the M rods:

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Quadrajet Carb Talk and Tips / Re: Secondary vacuum draw vs air door opening - test
« Last post by novadude on January 23, 2026, 09:56:28 AM »
Interesting, but I'm not sure I understand what is happening from 1.35 to 1.45?  Also, would more CFM change the result from 1.2 to 1.35"?  Intuitively, you would think that smaller door opening would pull harder on the well, but maybe this doesn't show up until you have more CFM air flow?
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Dialing in your rebuilt Quadrajet carburetor / Re: Adjusting Secondary Air Flaps
« Last post by jagness on January 22, 2026, 03:04:35 PM »
Big surprise! Cliff was right again. I had made a lot of progress on this problem, but never completely eliminated the bog. So I modified a 4 hole spacer into a divided spacer (divider down the center), and that worked. Now there is no bog whatsoever. So if Cliff recommends something, you might want to try it before you argue with him. In my experience, his advice has always been right on the money. Thanks again Cliff!
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Quadrajet Carb Talk and Tips / Re: Secondary vacuum draw vs air door opening - test
« Last post by 77cruiser on January 21, 2026, 03:11:20 PM »
That's pretty cool.
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Quadrajet Carb Talk and Tips / Re: 71 T/A 455 HO build
« Last post by Will B on January 21, 2026, 01:37:15 PM »
It's alive!

https://youtube.com/shorts/aVpUbiHDcxE?si=2gc7YCJT8q1aGZ41
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Quadrajet Carb Talk and Tips / Secondary vacuum draw vs air door opening - test
« Last post by 70GS455 on January 21, 2026, 01:20:01 PM »
I have built a crude flow test bench using a fabricated box to adapt my 7043240 to my leaf blower. It flows about 450 cfm, and with the primaries closed and secondary butterflies zip tied open, provides a relatively close approximation of a flow bench. I wanted to measure the secondary vacuum draw as a function of the rear air door opening ( my carb has an adjustable stop screw with the stop ground down). The carb is instrumented to provide the vacuum depression present in the secondary main wells by 2 tubes sealed to the jet discs in the floor of the bowl, and the secondary air bleed/emulsion tubes soldered shut. I have both a digital and home made water manometer to measure vacuum. The door measurement method is the one depicted in Cliff's book.

The blower is powered by an adjustable regulated power supply although I did not adjust it for flow or depression across the carb as the door was varied so bear that in mind. The blower is not a positive displacement pump.

The graph shows the recorded pressures and surprisingly the vacuum does not drop off very much and drops only when the door is almost vertical. The drop due to the door closing I believe is a limitation of my setup; the velocity has slowed and I did not adjust to maintain constant flow.

I do realize the door will be close to the discharge nozzles when open that much but I have scarf cut mine on the bottom to allow plenty of room for the emulsified mixture to escape. BTW, my engine made 590 HP/ 608 ft lbs on the last dyno test. I plan to resume testing and air door vs hp will be tested.
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