Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Dialing in your rebuilt Quadrajet carburetor => Topic started by: MRSOFTE on December 21, 2016, 04:18:50 PM
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Good morning
Finally got too the point where I felt tuning my 7028210 by the seat of my pants was over. So I sprung for an AF gauge. So with 69 jets and 46rods and AX secondary rods on a K hanger. It idles at 13.7. heavy acceleration with out the secondary's is also mid 13's. Cruise is 14.6 to 51.1. I'm happy with that but maybe I could go a tiny bit leaner?
Anyway my question is....When the secondary's open it drops too 10.6- 11.1. Is that good/normal???
Thank you!
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If it goes back 12 -13 it's OK. If not you should lean it out.
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When you say you could go a little leaner, do you mean at idle or cruise speed ? Is that a stock motor or does it have a non factory camshaft ?
Assuming it's a pretty stock motor with plenty of vacuum, I do run leaner than that at idle myself and also a bit leaner at cruise as well. It's easier to changer the cruise AF with the later APT carbs like I run, but if I were you, here's what I would do, but that is just me. I would slightly enlarge the upper idle air bleed which is most likely on the air horn on your carb. That would lean out the idle and also have a small influence on the cruise AFR as well, but much more on the idle which I think you could lean out more.
Frank.
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I think he's mainly concerned with WOT with secondaries hooked up. Sounds like it needs to be leaned a little on the secondary side.
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Yes just WOT. Stock 396 and the Rochester has not been abused by a weird rebuild. The carb has the stock AX rods, I have two hangers a K and M the M is leaner that's the one I'm using. Adjusted the door tension until it bogged then tighten up a bit. Not sure what else too try? :P
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AX rods are pretty rich at .0400. I'd try DA's which are .0443. If still too rich try something in the range of AU's which are .0530.
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question for the group some say 10 some 12 where are you getting these as good numbers . stop light to stoplight . 1/4 mile . i got 5 11 to 1 pistons and a bad block sitting here . but that was 2 0r 3 miles racing someone flat on the floor so the question is what would be a good number for that type of run?