Engine pops when I push in the clutch
 

I recently reset my timing and adjusted the carb to get the idle right. I've been noticing a "pop" or two when I push in the clutch. It's not a backfire just a "pop". I think it may be coming from the carb but I've been driving with the top down so I can be sure. My engine is a low mililage rebuild and has a Simmons HC head and Zenith carb. I had to adjust the carb quite a bit to get the idle speed down. I've since turned the mixture up a bit but no change. I thought I'd ask here before going further. Any suggestions would be appreciated. Thanks

Steve

Re: Engine pops when I push in the clutch
 

Well, I'll bite and take a stab at this.. I'm going to assume that you're talking about a 'bloop' between no throttle shifts.. I have no idea what is meant by turning the mixture up.. How much have you played with GAV, idle mixture, idle speed, or timing setting ?? You could well have a slight vacuum or exhaust leak.. Since you call this a 'pop' when pushing the pedal I'm also wondering if this has nothing to do with engine operation and may be something mechanical such as dry or binding clutch linkage,etc.

Re: Engine pops when I push in the clutch
 

Yep, I think Patrick is correct in that it appears your fuel mixture is too lean. Could be GAV setting, ...or a vacuum leak. One thing to note is generally if there is an exhaust leak at the manifold or muffler clamp, it will cause the fuel mixture to be a tad rich if anything because the carburetor is trying to inhale the exhaust fumes which the carbon monoxide tends to kill the oxygen in the fuel mixture thus richening up the mixture.

Re: Engine pops when I push in the clutch
 

Are you sure it is an engine pop? Maybe the clutch pedal hitting a battery cable?

Re: Engine pops when I push in the clutch
 

I'm sure it's a pop. I think that you are on to something with the GAV. I've always kept it about a quarter open and I never changed that habit after I made the timing and carb adjustments. I feel like an idiot for not thinking of that.

What I meant by turning the mixture up was richening the fuel to air ratio.

Re: Engine pops when I push in the clutch
 

The pop is most likely from a gas air mixture that is lean. It happens when you push in the clutch because you also just took your foot off the gas pedal. It is the closing of the carb that forces the fuel mixture to an even leaner condition. My guess anyway!
Good Day!