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terrymason |
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#1
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Member ![]() ![]() Group: Members Posts: 346 Joined: 23-November 05 From: Virginia Beach Member No.: 5,174 ![]() |
The problem - The car will go very lean around 2500 rpm, as if the pump jets were too small.
History: New fuel pump (3.5 PSI to each carb) 55 idle jets 55 pump jets 140 main jets 175 air correctors These carbs are new to the car, and I'm trying to dial them in. The car is lean when I first start it (16 / 17 on my air / fuel gauge), but then levels out to a nice 14.7 idle when warmed up. While driving, I can give the car 20% or so of the pedal, and drive up to highway speeds nicely, but when I goose it, it will go very lean (18-22 on my gauge) followed by a series of backfires and loss of power. I started off with 35 pump jets, and have moved up to 55s, which appear to be the most popular around here. I've also adjusted the pump jet linkage, from the nut fully loosened, and moved it in as far as it would go before affecting the main throttle shaft (like 60 turns or something). What do you guys think, do I need 75 pump jets? |
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terrymason |
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#2
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Member ![]() ![]() Group: Members Posts: 346 Joined: 23-November 05 From: Virginia Beach Member No.: 5,174 ![]() |
OK, I have made some big headway on this. I pulled all the jets from the car, and blew them out with carb cleaner, along with the places they go. Replaced my 52 idle jets with 60s.
I think cranked the idle up to 2500, and used my unisyn gauge to check the flow. The passenger was a 5, while the driver was at 12. I adjusted the linkage so that they are both at 11 around 2500 rpm. I then addressed my mixture, making all screws 2.5 turns out. I then adjusted my pump jets. turning them about midway out. They were previously all the way tightened (I was trying to get a larger pump squirt) I finally closed all my air bypass screws. Now, the car idles around 10.5 a/f (probably from the 60 idle jets). It drives 100% better, but still goes lean when it starts to pull (2nd gear feels it most). It also seems that if I goose the gas it will go lean. |
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