General Category > Quadrajet Carb Talk and Tips
I need the stock specs for a 17050213.
GSP7:
Whats the 17080231"C" ?
--- Quote from: Kenth on November 18, 2025, 03:07:46 AM ---This is what i have on the 1980 350 HD Truck 17080213 Rochester and Carter units.
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--- End quote ---
Kenth:
C is the Carter mfd Quadrajet.
GSP7:
I have a Rochester 17080213 that had 73 jets and 49 rods
Cadman-iac:
Well I've had to continue to calibrate this one, not sure why the results of the tip in test were spot on by Cliff's book, but on the road test it ran lean.
It took multiple jet and rod changes to pin down the right combination that yielded good results.
What's really weird is that with a 71 jet and a 44 rod it ran lean, but with a 72 jet and a 44 rod it ran rich.
I ended up going with 70 jet and a 41 rod to get the afr into the correct range. The 71/44 combo gives a cruise area of 2.43, which apparently is not enough, yet the 72/44 combo with an area of 2.55 proved too much.
So going through what I have on hand, I had a couple of options, a 69/40 giving me 2.48 cruise and 3.20 WOT, and a 70/41 with 2.52 cruise area and 3.31 WOT. And since the 72/44 combo was rich at WOT as well, with 2.55/3.54, the smaller jet/rod combination brought the AFR closer to optimum.
Even though it's running much better now, the tip in procedure is indicating that it's running rich.
I may have to try another combination to see just how far it will go, but I'll have to order a couple of rod sets in order to find out.
If I go with a 71/43, that'll give me a 2.50/3.42 cruise/WOT area, or a 72/45, which gives a 2.48/3.52, but that keeps the WOT area too big and too rich.
The other things I had to change were the air valve spring setting, that went back to 1 turn, and the secondary rods are now a pair of CT's instead of DP's. The WOT AFR is now around 11.0 at 3500 rpm.
I also had to go to a .067 on the LIAB's to get the off-idle mixture correct.
I tried advancing the timing to 16° initial, but I think that's a bit much, I'm afraid I won't hear any detonation if it occurs, so I reset it back to 10°.
On another note, I was getting a fluctuating AFR at idle still even after replacing the well plugs. It was much improved, but still noticeable. So upon disassembling it after leaving it sit overnight, I noticed that there was fuel in one of the small pockets next to the accelerator pump well, and the bypass air passage looked like it was wet as well.
Looking at the air horn it had a slight curve at the front, so I filed it flat in the hope of stopping any fuel from leaking into the bypass passage.
I haven't had it off and apart since installing order to check for leakage, but the AFR doesn't seem to fluctuate as much now.
It was going from 13.5 to 13.9 and back at idle, now the fluctuations are just like .2 instead of a .4.
Novadude, what is your AFR range when you're cruising at around 3000 rpm at light throttle? Mine runs around 15.2 to 15.5 and I'm wondering if it's still a bit rich.
And at a WOT, just how rich should your AFR be? I've been shooting for around 11.0 to 11.5, but I really don't know if that's too lean, or too rich, or just right.
My thanks again to you guys for all your help, Novadude, 77cruiser, Kenth, MCX, and Cliff.
Cadman-iac:
I wanted to share how I locked out the secondaries this time. Last time I used a wire to keep the secondaries from opening by wrapping it around the lockout lever and the shaft. The problem with that method was that it caused the secondary throttle shaft to move to the right side and not allow the plates/blades to close correctly, resulting in a vacuum leak.
The wire apparently jammed between the base plate and the little pin that goes through the shaft.
So to prevent that this time I made a bracket that bolts to the side of the carb where a rear pull-off would typically go, and it fits against the pin in the shaft.
Another tip for locating an internal fuel leak is to use a blue Sharpie to color the surface around the suspected leak. If it is leaking, the ink will run showing the source.
Since it's not possible to use a camera to actually see what's going on inside the carburetor, I figured if you could use something to cover the surfaces that would come off with fuel, that would hopefully show you where it's leaking.
I initially tried this on the well plugs which revealed multiple leaks. So this time I "painted" the bypass air passages and set screws in the base plate, but I haven't taken the carb off and apart yet to see what is happening yet. When I do, I'll post a picture of the results.
Another thing that I do to keep the idle mixture screws in "synch" is to paint the heads of the screws so it's easier for me to see. I paint one half of the screw head with a red welding marker and the other half with a yellow marker.
Because I wear trifocal glasses it's sometimes hard to focus on the screws when I'm working on it in the evening, so this helps me see them better. If the red halves are both towards the left or right side, then I have them "synched". Its really easy to lose count of how far you've turned them, especially if your screwdriver slips off. I didn't think to get a picture of them though, but next time I've got the carb off I'll get one and post it.
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