General Category > Quadrajet Carb Talk and Tips
I need the stock specs for a 17050213.
77cruiser:
At cruise mine runs about the same as yours, but at WOT I'm around 12.5 -13. I'm running non ethanol gas 91 oct.
novadude:
--- Quote from: Cadman-iac on December 09, 2025, 08:11:26 PM ---
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.
--- End quote ---
My car with a Muncie and 3.36 gears and a ~26" tall tire runs down the highway at ~3100 rpm. I am right in that 15.2-15.5 AFR range. Crowding the throttle, it will swing to ~16.5:1 before power enrichment / secondary opening. WOT is ~12.5-13.0 range. Seems to get great MPG set-up this way, and there are no drivability issues. It is very responsive. At idle, the meter shows around 13.0, and light throttle in the < 15 to 40 mph range is 14.3-15.0.
Cadman-iac:
--- Quote from: 77cruiser on December 10, 2025, 12:56:27 PM ---At cruise mine runs about the same as yours, but at WOT I'm around 12.5 -13. I'm running non ethanol gas 91 oct.
--- End quote ---
I'm just running 87 octane pump gas with ethanol, my AFR at WOTwas hitting as rich as 10.0, and probably worse, but the gage will only register to 10.0. I don't know, but I keep thinking that's too rich. At 11.0, I'm guessing that is too rich yet.
So do you know which way the AFR goes between fuel with ethanol and without? If I'm getting 11.0 with ethanol, would this same setup give me a leaner AFR without ethanol, or does it run richer?
Do you recalibrate for ethanol free fuel, or is there not enough of a difference between the two fuels to bother with it?
Thanks for your help.
Rick
Cadman-iac:
--- Quote from: novadude on December 11, 2025, 08:10:48 AM ---My car with a Muncie and 3.36 gears and a ~26" tall tire runs down the highway at ~3100 rpm. I am right in that 15.2-15.5 AFR range. Crowding the throttle, it will swing to ~16.5:1 before power enrichment / secondary opening. WOT is ~12.5-13.0 range. Seems to get great MPG set-up this way, and there are no drivability issues. It is very responsive. At idle, the meter shows around 13.0, and light throttle in the < 15 to 40 mph range is 14.3-15.0.
--- End quote ---
That sounds like what mine is doing, except for the WOT AFR. My cruise AFR is almost identical to what you reported, so i think I've got the primary side set just about right. Going to the smaller rods and jets cut the WOT AFR with just the primary side to about 12.0 if I remember correctly. I might have to lock out the secondaries again and recheck it to be sure.
But do you think a good WOT AFR would be somewhere around 13.0, or is that too lean?
This ain't no hotrod, it's a 3/4 ton suburban with a 3.73 rear gear and a LT235/85R16 tire, gotta measure them again, but I think they're 28" tall.
My rpm at 75 is about 3200-3300 if memory serves. To verify that I have to either hope the local cops are having their morning coffee or drive 45 miles to get to the interstate, lol.
Maybe an AFR of 12.5 at WOT because of how heavy this thing is would be better, I honestly don't know.
I'd like to get it to where it gets decent mileage, I've got a LOT of scrap metal I need to haul to Tucson next summer, so it'd be nice if the scrap would cover the cost of the gas at least.
Thank you for replying.
Rick
Cadman-iac:
Here's a couple of pictures of how I marked my idle mixture screws to keep them synched with each other. Not foolproof but every little bit helps when it's hard to see them hiding underneath the carb and all kinds of stuff in the way.
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