TOPIC: Carb adjustment

Hey All,

In was trying to tune in my freshly rebuilt carb last night and ran into some problems. The engine is a 1962 johnson 40hp.

When I adjust the low speed so that it runs smoothly at idle, midrange develops a buck or sneeze. If i adjust the carb so that midrange no longer sneezes, it will buck or sneeze at idle. I cant seem to find a happy medium.

Im wondering if there is something i am missing? I've had the carb apart several times and i dont think i missed any passages.

Im wondering at what point is the fuel flow measured by the fixed main jet and not the low speed needle? Is midrange supposed to be controlled by the high speed or low speed cicuit?

also, im not sure if it matters or not, but i was doing all tuning with the engine running on the hose, not under load.

Any ideas?

Thanks in advance!
Scott

All the fuel goes through the fixed high speed jet.

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Sneeze means it is running lean on the low speed jet or throttle is opening too soon.----The rod that goes back to the tower shaft has a collar that can be adjusted.---Often times folks adjust that because there is a gap at idle position.--That gap should be there !!----It is often adjusted because it " looks to be wrong " and then throttle opens too soon.

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Not saying that is the issue here but it has to be checked on your motor.

Thanks for the thoughts. I know exactly which collar you are referring to, and now that i think about it, i dont remeber seeing a gap at idle. (could be wrong though). Ill have to check it out tonight.