Thread: O-320 Help!
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Old 01-20-2020, 01:00 PM
RVDan RVDan is offline
Join Date: Jun 2012
Location: Frederick, MD
Posts: 965

Originally Posted by 8213C View Post
Thanks for the input. Prior to the new carb the #3 cylinder was running 1390 in cruise configuration. The prop shouldn't have been messed with when the new carb went on. Ill have to try to move them and see what reading i get. My mechanic claimed he matched the serial #of the old carb to the new one, but could be the old was modified and we dont know it.
So one of the problems with messing with the carb jet sizes is that you can?t really match it by carb p/n. The engine and prop combo determine the proper carb p/ n. If you have a constant speed prop vs a fixed pitch, it can change the jet requirements. When you drill or ream out a jet, you fix your problem, but create a new carb configuration, that you can?t buy or possibly get overhauled without what you get back being different. There are several p/ns of carbs that are the same except for jetting.
That said, total fuel flow can be used to see if the jetting is off.
Dan Morris
Frederick, MD
PA28-140 sold
Hph 304CZ sold
RV6 built and sold
N199EC RV6A flying
Retired Aerospace Engineer and A&P/IA
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