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I found the APT spring missing as well. Probably when it was apart someone lost it.
Bet it ran nice and lean all the time like that. Might even be why it was removed from the car and shelved.
From: At my Bar drinking and wrenching in Lafayette Colorado
I assume you're referring to the Power Piston Spring. The reason that many are missing is that people don't see that there is a spring in the piston bore when they take the carb apart. During cleanup, the spring falls out. They either don't notice it falling out, or it hits the floor and goes bouncing off to an irrecoverable location. So the carb is re-assembled without it. Very common issue.
Lars
I assume you're referring to the Power Piston Spring. The reason that many are missing is that people don't see that there is a spring in the piston bore when they take the carb apart. During cleanup, the spring falls out. They either don't notice it falling out, or it hits the floor and goes bouncing off to an irrecoverable location. So the carb is re-assembled without it. Very common issue.
Lars
Yes, power piston spring. Terminology, lol, purely layman here.
Last edited by REELAV8R; Aug 16, 2021 at 12:27 PM.
It's kind of a tough business selling rebuilt carbs to the general public like Summit is trying. You just don't know what the skill level is of the guy who laid down his credit card, or what other problems his engine might have. I've known a number of guys who've called themselves 'mechanics' who I wouldn't let put a hubcap back on my car (and I'm sure you guys have too). Are there vacuum leaks? Timing Issues? Other fuel-related issues? The customer is NEVER wrong!
Quick story: Years ago the company I worked for was selling one of the first 'smart' networking thermostats. We were targeting the light commercial market (office buildings, malls, chain stores, schools, etc). We were selling to mechanical contractors who were factory trained (at our factory ...by us), how to use it, how to wire it, how to hook it all up, software. We pretty much held their hands (where required) on projects, and provided unlimited phone support. Still, we had so many contractors badmouth the product, "It's crap", "Doesn't work for $ht!" and so on. They were 'going to sue our a$$', etc. I drove multiple states away with our lead engineer and we looked at many installations for a few years where a contractor was at witts' end and was blaming our product up and down.
In every instance, we found just about every mistake in the book that we trained them NOT to do!! Communication wires run parallel inside high-voltage conduit, thermostats with the same addresses (how many times did we explain that!!?). Bent eProm pins. Wrong voltage to the thermostats (C'mon!), I could go on and on. And they were all things they swore on tech support they had quadruple-checked! On one particular installation with over 100+ thermostats, they claimed 75 were a factory defect. And the system didn't work right, software no good. In a half a day we found and documented every mistake and there were a couple thermostats we couldn't get to work (which our techs later determined in the lab were fried by over-voltage). We left with a proper running system. This level of stupidity happened more than you might think. We had to stop 'trusting' your wanna-be contractors and only sell to guys we determined could install it properly (which wasn't that difficult).
I hope Summit's rebuilders figure out how to do a good job on them and deliver to the general public. It would be a boon to a lot of classic car owners. But they're going to get a few bruises along the way from guys who the carb may not even be the issue, or dropped it on the concrete floor, or dog scratched dirt into it on the shop floor. And the 'customer is always right', LOL. I'm sure Lars could tell a few stories too....
I'm sure that Summit just buys them from some jobber in a foreign country...like Mexico....or China. I seriously doubt that Summit has any 'hands-on' hardware mechanics in their employ.
This carb was taken apart enough to do the usual adjustments. A great exercise in diagnosing problems, and this Qjet is already on its way back to Summit. Bad carb, good customer service; in stock parts always get here in two days and include a return shipping label.
Overall this carb was not completely cleaned out, and not assembled using any bench settings. Secondary choke pull-off only and it has to move over 1/2 way before it does anything. Primaries open 5* shy of all the way and by that time secondaries are 5* past vertical. Accel pump is very sticky. Float level set to 0.8, with float pin clip thru one of the holes in the float arm. Jets are the same size .076, but one of them has a short passage due to hollow on the bottom. Primary rods (42) with a little curve in the tip. Secondary rods DD (0.103” tip, taper right to the tip).
The rust oozing out from around the throttle shaft and their amount of play, even with bushings, were the most worrisome.
Cliff, Lars and others and been writing for YEARS about how to put a Qjet together and how commercial rebuilders allow such poor quality control. Shame on these commercial rebuilders; they are destroying perfectly serviceable Qjets by the thousands. 1975-1979 AT and electric choke
Bushing fit and how much more crud is there were you can’t see it?
Not what the little holes are for! Someone didn’t read up on COMMON assembly errors.
A little curve in the tip
Any comments on this difference?
Didn’t check for reamed-out secondary jets to go with these really fat rods. Squished in tip on fuel outlet. What is the flap spot-welded to the air valve?
From: At my Bar drinking and wrenching in Lafayette Colorado
Thanks for the excellent photos and inspection. Carb looks about like what I would anticipate, and it's pretty bad. Additionally, that carb is a truck-specific carb - not a passenger car application. Another real hack job commercially built carb..!
