Why am I running lean all of a sudden??
 

540 with a Whipple, BG King Demon Carb.

Mallory fuel pump and regulator-non return style.

Mechanical pressure guage @ idle was 8 1/2. At speed electric guage on dash would drop to around 7 and bounce +/- a little

Motor was running a little fat, especially at idle. plug readings were black after idling in to dock. After a hard run they were a little cleaner looking.

2 weeks ago I felt a stumble at about 5200 rpm. Back at the dock I checked the plugs and they were pure white.

This weekend, between rain showers, I took a ride after installing mech. guage at the dash. Never went above 3500 rpm, had my 2 1/2 yr old daughter with me. Fuel pressure @ idle was 8 3/4 and 8 @ 3500 rpm. Back at the dock I checked plugs and again they were white. Rear plugs were a little darker and wet with fuel.

Also discovered distributor was loose. Have not had a chance to check timing.

I have not had a chance to check to see if jets are clogged.
Ful/water sep. has been changed and found no debris.
Just looking for any other thoughts.

Thanks

Re: Why am I running lean all of a sudden??
 

start by checking float levels.

Re: Why am I running lean all of a sudden??
 

Bowls are actually higher than before, thats why I think maybe I have a clogged jet.

Re: Why am I running lean all of a sudden??
 

timing will have an effet on jetting, probably was way too far advanced, reset timing check your jets and reset your float levels. good luck. if they still look lean you may have gotten some bad gas.

Re: Why am I running lean all of a sudden??
 

Start with the timing.

Re: Why am I running lean all of a sudden??
 

Ditto! Unless you want to hurt it!

Re: Why am I running lean all of a sudden??
 

Start with the timing. Once you've done that if you're still having problems make sure you don't have any dirt caught up in the carbs. Carburetors won't change their calibration on there own, so something has to have changed. Most likely your timing if the dist is loose.