General Category > Quadrajet Carb Talk and Tips
I need the stock specs for a 17050213.
Cadman-iac:
Well, this carburetor runs rich from off-idle to 3500 rpm. It's not the timing.
I noticed that this one has a .016" smaller LIAB than the other 3 previous carbs, so is this the whole problem with the other 3, the LIAB's were just too big?
And how would I get this one to lean out a bit in the off-idle to 1500rpm range? Enlarge the LIAB'S slightly?
Something else I noticed is that the jet/rod combination in this 17080213 carb, (#72/49M), has a cruise metering area of 2.19 thousands of a square inch, yet runs much richer than two of the other carburetors that have a jet/rod, (#72/44 from Cliff), metering area of 2.55 thousands of a square inch, and the 3rd one has a metering area of 2.52 thousands of a square inch, (#70/41K). What's up with that?
Does the LIAB's have that much effect on the AFR?
77cruiser:
Have you tried adjusting the APT on this carb? How's heavy part throttle?
Cadman-iac:
--- Quote from: 77cruiser on November 18, 2025, 06:53:53 PM ---Have you tried adjusting the APT on this carb? How's heavy part throttle?
--- End quote ---
No, not yet, it was just getting dark when I got back from the test drive. I do need to look at that, I didn't think about it being set too high. I set it at 3 3/4 turns according to the specs I got from Kenth. I thought it was a bit much right off the bat, I don't usually run it up until I try it set at minimum first. But since I was trying to set this one up exactly like it left the factory I figured I'd try it and see how it works.
I'll give that a try before I do anything else.
But if this doesn't change it, would the LIAB's be a possible cause?
The heavy part throttle is rich as well. I don't remember the reading, I forgot to bring my recorder for notes this time. But it's definitely fat from top to bottom.
Im actually glad too, I was beginning to think I had some other problems with the engine instead of the carburetion. This just proved it.
Thanks for the suggestion.
novadude:
I think the LIAB could definitely be part of the problem with the other carb. I've found that 0.062 vs 0.078 just seems to work better for off-idle. As for metering area... I don't think you can compare SMAB carbs with DMAB, as they seem to behave different with regards to main system metering area.
I've shrunk the LIABs with an old accelerator pump ball and a punch, and cleaned up with a drill. This doesn't always go smooth though, so be careful.
Cadman-iac:
--- Quote from: novadude on November 19, 2025, 05:25:18 AM ---I think the LIAB could definitely be part of the problem with the other carb. I've found that 0.062 vs 0.078 just seems to work better for off-idle. As for metering area... I don't think you can compare SMAB carbs with DMAB, as they seem to behave different with regards to main system metering area.
--- End quote ---
Novadude,
The last carb was a SMAB, #17084226, and it had a larger metering area than this one does.
I'll start with adjusting the APT, and if it doesn't work I'll make the LIAB's on this 17080213 replaceable with set screws, and try smaller ones until it gets into an acceptable AFR range. Hopefully it doesn't change anything else. The higher RPM mixture can be fixed with the jet/rod combo and the APT setting.
The difference between these two is definitely confusing, but I'm gonna figure it out, it might take me a while, but I'll get there, (most likely with help from you guys).
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version