B carb fuel starvation
 

Friend sent me this B carb to check over ( it is fitted to a stock A engine with gravity feed tank) - All the symptoms he describes (stalling/stuttering when trying to power up hill etc )point to fuel starvation. Fuel level is 5/8 inch below gasket
No surge baffle with the float (has it been removed or are some like that?}Is the baffle essential?
Fow rates test out ( ml/min at 36 inch): main 88, cap 390, comp 158, power 35. Biggars book recommends, main 136-142, cap 372-462, comp 110-118, power 110-118. I don't want to take all the airway plugs out- the carb looks very clean. Apart from some of the jets being obviously way out are any other things I should be aware of?
Attachment 276326

Re: B carb fuel starvation
 

Your starving fuel because of a plugged main jet. Get them all to specs first. Check your throttle shaft for wear.

Re: B carb fuel starvation
 

Also check the ignition, many carb are actually ignition problems.

Re: B carb fuel starvation
 

has he opened the GAV more.....it is there to play with....many fuel starvation issues are because the GAV is turned in too far....don't be afraid of it

Re: B carb fuel starvation
 

Chuck Sea, the throttle shaft certainly has some play. I find the A carb is fairly forgiving with throttle shaft wear... But is it more critical on the B carb? Would this play cause lack of suction up the power jet, with the controlled port leaking?

Re: B carb fuel starvation
 

I would get the main and power jet back to Biggars specs, and make sure the tube leading to the throttle shaft is clear, the B carb doesn't need the GAV after warmup which eliminates that, I don't believe the throttle shaft is a problem, should you need one they are now available

Re: B carb fuel starvation
 

Make sure the small hole in the throat or passage way , where the fuel from the pickup tube exits when the throttle is opened, is not plugged.

Ron

Re: B carb fuel starvation
 

I don't know anything about a B carb, but if the fuel line goes in too far, like it can on an A carb, and hits the screen in the carb, this is exactly what happens. A little circumcision of the tube will fix it.

Re: B carb fuel starvation
 

The 32 B and 33-34 C passage ways and throat is no way like the Zenith- or Holley Carburetors that came on the A.

Ron

Re: B carb fuel starvation
 

check to see what color the spark is and how far it jumps.