Swapping Q-jet bodies and guts, Frankenstein style

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Radiohead

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I've been reading around the internet and as usual, it only creates new questions needing answered. I figure the brain trust here has probably heard of my problem and what it takes for a good and proper jury rigging. Here's the dilemma.

Basically I ruined the body of the carb I have by overtightening the fuel filter housing and cracking the aluminum. I doubt it is a weldable problem so I'm not going to waste time on that course of action. I do have a newer model Q-jet not doing anything so I thought I would just swap them over and be done with it.

The spare carb came off an early 80's 305 and I'm trying to feed a 454. I read that carbs that came on big blocks have larger passages for bleed air due to higher volume at idle and that small block spec'd units won't work properly. Is there any truth to this statement? It's so hard to separate the wheat from chaff these days.

I can't definitively answer the question now because the needle and seat won't let any fuel in the bowl. This carb sat out in a moist area for several years and between the rust and ethanol corrosion, it's apparently plugged up tighter than a well diggers bunghole. It would require a cleaning just to test its efficacy for the task. So, my thought was to swap the main housing out with all the guts from the original in hopes of cobbling up a solution to the problem for the cost of a good kit and some time to perform the operation.

I suppose what I'm trying to decide is whether or not it's worth the effort. Can I swap out my throttle blade section and top horn over onto this other, newer housing and have it do what it's supposed to do? I'm not experienced with this level of carb dallying and don't want to cause a six month hair tearing session over some arcane but important factor. Keep it cheap plays well here, but if I need to get a replacement unit from a specialist, so be it.

Have any of you tried to do what I am proposing? Or something similar? As always, your feedback is appreciated in the highest order. And thanks for taking the time to read my thread post.

Details - 1979 c20, 7.4 CA emissions, original carb # 17059520 with the heat crossover style choke and the donor carb # is 17084426 with an electric choke version. I hate Amazon but I am looking at getting that Q-jet book anyway.

Cheers!
 

ali_c20

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Measure the bleed holes, idle down tubes, jets and metering rods on both carbs to see where they differ.
I think swapping parts and increasing some hole sizes should work with the right Q-jet book.
That's my guess but I could be completely wrong.
 

fast 99

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Reading up on these carbs is a good idea.

Q jets are vehicle, engine, emissions specific. I have mixed housings when one section is not usable, swapping as many original parts as possible. It's not ideal especially if an infrared isn't available. You may have some driveability issues to contend with but can be done. If possible try to find a used replacement for rebuild. Many are for sale on e bay. Just be sure to ask if water ever got in the bowl. Most of those are junk.

There used to be a repair kit for the fuel filter area, unsure if it is still made. Do not buy a new reproduction carb. There have been quality issues.
 

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