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Cevan |
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Senior Member ![]() ![]() ![]() Group: Members Posts: 1,079 Joined: 11-December 06 From: Western Massachusetts Member No.: 7,351 ![]() |
I'm trying to sync the carbs (Weber IDFs) on my new engine. I warmed it up and then let it idle at about 800 rpms. I disconnected the linkage and used the synchometer. On one carb, both barrels were very close to each other (5 and almost 5), while the other carb read a 5 and a 3. Is this indicative of a bent shaft or some other problem, or can this be adjusted?
I do recall removing the throttle plates from one of the carbs while I was cleaning them. I was going to remove the shaft but decided against it and put the plates back on. Might I have changed the position of one or both of the throttle plates in relation to the bore? Would this cause the problem? Also, fuel seems to be almost weeping in the area of the brass bolt and washer (#5 and 6 in the picture) directly under where the feed line connects to the carb. I used a new washer and tightened the bolt real good. Any ideas? ![]() |
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IronHillRestorations |
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I. I. R. C. ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 6,828 Joined: 18-March 03 From: West TN Member No.: 439 Region Association: None ![]() ![]() |
Chris, unfortunately there could be a few other factors that are causing one cylinder to pull less, valve adjustment, lower compression in that cylinder, intake leak, right off the top of my head. You also need to make sure there isn't an air leak on that velocity stack.
Do a search for carb tuning, and you'll probably find my method. The key for the air bypass is to start with all of them screwed all the way in on thier seats, find the barrel that's pulling the most, and match the others to that one. I'm not 100% sure, and it's been a while since I've had a set of those carbs apart, but I think there's only one way to put the throttle plates. The aluminum sealing washers can be a pain to get to seal. You will probably have to just tighten them a bit more. When you could get new Weber 3 barrels, they torqued the heck out of covers for the float valves, to the point that you could strip the hex head on the cover plugs. PMO used to and probably still sells fiber sealing washers that didn't require that much torque. |
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