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O.k., it's time to ask for help. As you may recall, I picked up a 79 Mikado. It coughed and sputtered on the way home. An inspection of the carb revealed it was full of sediment and debris. I picked up a NOS Holley rebuild off e-bay (I think I was bidding against one of you guys!) Installed it, and can't get the truck below 1200-1300 rpm. Just as it tries to transition to the idle circuit, it dies. Using some carb cleaner, I found a vac leak on the back side of the carb, down where the flange meets the intake manifold. Can't pinpoint it exactly, but it's back there somewhere. I've tried a couple different things. I took out the spacer and extra gasket, and just put the carb and one gasket on. Still vac leak. Tried some non-hardening gasket maker, made a friggin mess. Tried rtv--still vac leak. I can't afford to spend $300-400 for a new weber setup. If someone can make me a deal on a weber setup, e-mail me. Otherwise, anybody have any ideas how to stop this **f8#@ vac leak ? Thanks.

How did you specifically find the leak? How did you go about it?

I used carb cleaner, and sprayed various areas. I started outward and worked inward. For example, I sprayed where the intake manifold meets the head, and got no reaction. I sprayed by the three tubes on the back side of the manifold, and got a small reaction. I moved up to the base of the carb, and got a significant change in engine rpm (up). I sprayed at the front of the carb, no reaction. I sprayed down the left side of the carb base and got a medium reaction. I sprayed down teh right side of the carb base and got a mild reaction. I went back to the back of the carb at the base and got the strongest rpm change. Does that tell you anything?

I had a similar problem and went thru 3 Hitachis before getting a Weber. Holley doesn't do a good job rebuilding. On one, that was driving me nuts, the bushing for the throttle plate shaft was leaking gas. Obviously, you don't see it with the engine running because of throat ventura vacuum. I found it on mine when I pumped the linkage that actuated the accelerator pump while the engine wasn't running and the gas dripped out of the rear bushing onto my hand. If it can leak gas, it can suck in air and degrade the fuel/air mixture.

O.k., good tip. I'll check that.