Hi.....I understand that a lean condition will cause pops on a downhill on compression. So I turned the screw at the base of my Rodchester B out about 1/2 turn from where it was set and it helped...but.....how much is enough. I'm afraid of losing the spring and needle. I have the engine tuned by the vacuum method and the needle is steady at 19 at 2800 foot elevation and about 650 rpm idle. She runs a treat but when on compression down a hill I get those small rumble farts which my wife hates. Thanks in advance for your help to us.
Steve