Backfiring |
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Backfiring |
BfloRandy |
Apr 10 2017, 06:02 PM
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#1
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Dimwit Extraordinaire Group: Members Posts: 66 Joined: 20-September 14 From: Buffalo, NY Member No.: 17,927 Region Association: North East States |
Happy Spring, aka fix your car so you can drive it all summer!
Having an issue tuning my Weber 40's. The car does run, and idles quite well, sounds smooth and even. If I rev beyond 3k, I get backfires. Starts fine too. Ordinarily I would assume it's a simple matter of resetting and resyncing. Passenger side carb is as it always has been, fine. Mix adjustment screws work normally, idle adjustment also. I see the squirt from the accelerator jets. Driver side, not so much. It's getting gas. For some reason, the mix screws have little to no effect. This is on BOTH cylinders. The only time I notice any change in the engine's sound is if I back them way way out, then I get backfiring and carb throat sneezing. Otherwise, I can have them set just about anywhere, including fully seated, and there is no difference. I've pulled the carb off, (three times now) torn it down and blown everything out a couple of times already. I did see some blockage in the idle jets and mains before I blew them out. I also noticed that I didn't see any squirt from the accelerator jets. I tore it down again, and fiddled with the pump (new last spring) and reassembled it. Accel jets now appear to work normally. It doesn't at all help that my kids decided to reorganize a ton of things, and I now can't find my Weber manual. (IMG:style_emoticons/default/chair.gif) Can anyone help? Thanks! |
BfloRandy |
Apr 13 2017, 04:02 PM
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#2
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Dimwit Extraordinaire Group: Members Posts: 66 Joined: 20-September 14 From: Buffalo, NY Member No.: 17,927 Region Association: North East States |
Ok, time for an update, and some replies.
Elliot, I have pulled the idle jets a few times, they're still pretty clear. Justin, yes, at 3k I'm moving to the mains. I replaced the jets last spring to conform to what is listed in the Weber manual. Now using 55 idles and 115 mains. Adjusting the idle mixture screws is necessary to set the carbs to best lean idle, isn't it? Cylinder 1 does nothing. Cylinder 2 gets rough if I open it WAY up, like 2 or 3 full turns. New plugs are going in in a few minutes, will check wires (though they're new last spring also) and timing, etc. George, so many questions! (IMG:style_emoticons/default/biggrin.gif) There is one prog port exposed below the throttle valve on Cylinder 2. Always been that way, hasn't had too much effect in the past. Idle screws worked normally. Yes, idle does drop a little when rotating the linkage bar manually, also always been this way, and the throttle valves appear to close fully. (Looked at them while it was off the car) Valves were adjusted late last summer. Idle speed was at about 1200, I have it at 950 now, hope to keep it there! Just synched the carbs, disconnected. Backfiring is actually worse now. Can't tell which carb is backfiring. Just reset float on driver's side, as it seems to be the issue. Will check passenger side in a bit when I'm pulling plugs. I get a nice stream of gas when I disconnect the line (only 3.5 psi) using a mechanical rotary pump I bought from CB Performance. I don't believe that is the issue. It's 10 times the crappy Facet one it replaced! |
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