I have a standard Holly 4Bll carburettor, the engine would NOT run slow so Ive set the timing at 10 degrees ( correct) and backed of the speed srew until it doesn't touch, then still no good so I backed off the CHOKE screw which allowed it to run slow, the engine runs relatively smooth but now has NO vacuum until I accelerate it, and a random POPPING noise. all plugs are ok the two fuel screws don't seem to make much difference either before or after I adjusted the speed. when I accelerate the engine ( still in the garage0 the vacuum appears good at 22-24 and NO POPPING at that speed. but when I let it idle the popping returns
Neil
Neil
Jul 3, 2013 at 5:27 AM