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I recently rebuilt the zenith carb on my 80 MGB. It runs much smoother, but until the manual choke is all the way in before warm-up, the engine revs as I'm shifting the gears. This dissipates afterchoke is pushed home, but is annoying for the first five or so minutes of driving. I believe all the vacuum hoses, carb gaskets, etc. are air tight. Throttle return spring is okay. Any suggestions?
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Car revs upon shifting gears
- Thread starter BKRTEE
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Adjust the choke so that the fast idle doesn't come in so soon when you pull the choke.
D
D
I could be wrong, as it has been a few years since I worked on a modern MGB with a Zenith, but I recall there being a stop screw for the fast idle lever controlled by the choke. You should be able to lower the fast idle with that screw stop so that the engine does not race during choked operation. Check and make sure you don't have a bent connector to the fast idle choke control too!
Bruce /ubbthreads/images/graemlins/cheers.gif
Bruce /ubbthreads/images/graemlins/cheers.gif
I bought a can of carb cleaner and sprayed around the carb to manifold joints. Seems I do have a leak of sorts on one side since the engine idle went up. I'll be taking the carb off again in the next couple days (as soon as I replace the 1/2" box-end wrench I somehow lost a couple days ago) to inspect and hopefully rectify. Then we'll see, I guess.
Leaks were not at the carb gaskets as I had thought. One was where the small tube from the gulp valve enters the manifold by the left side of carb. The large nut w/copper washer that holds the gulp valve bracket was also loose. I also backed off the fast idle a bit and snugged up the manifold nuts. Will see tomorrow how it runs tomorrow.
No difference in rev problem, but she seems to idle a little smoother when warm, so at least there was an improvement in something.
The original water choke was replaced by a manual one before I bought it. Is the plastic "stepped" cam inside the assembly supposed to move a bit independently from the rest of the cam or could that have been damaged somehow? It returns to a normal position slower than the rest of the assembly when I manually move the choke piston with the cover removed.
The original water choke was replaced by a manual one before I bought it. Is the plastic "stepped" cam inside the assembly supposed to move a bit independently from the rest of the cam or could that have been damaged somehow? It returns to a normal position slower than the rest of the assembly when I manually move the choke piston with the cover removed.