I’m trying to sort out why my engine is missing at 2000-3000 rpm under heavy throttle load but not medium, looking at whether the engine is being starved by low fuel level at jets. I have the float levels set correctly per the manual and see the fuel level is at top of jet in front carb but not visible in rear. Should I try to raise rear level by raising float? Also, I just noticed that the rear float bowl is about 1/8" lower than the front in relation to its carburetor body, doesn’t seem correct but I don’t really know. Can anyone help me understand?
Have you already conformed the health of your ignition system? Points, plugs, plug wires, timing etc?
Yes, thanks…I think we’re ok there and that it is a fuel/carburetion problem.
How about a partially sunk float? They leak. I’ve had it happen twice, so I always carry a spare float.
I only mention ignition since those engine conditions
Full throttle, low speed generate high combustion pressure, which results in higher resistance across your spark plug gap. Increases voltage so alternate path to ground my be found. My carb problems normally get traced back to a Lucas part…
thank you. i checked that out, no problem at the moment.
I hadn’t thought of this, but how do you check it? All the ignition wires seem ok, not old, and the plugs are new too.
New points and condenser? To check for ignition wiring issues, open the bonnet at night while running and check for sparking wires. Can also spray mist wires with water while idling to see if idle gets rough or slows down.
thanks for the tips, Kris. i do need to go thru the ignition system again.
Are the SU needles correct, and correctly installed? I have an E where it would misfire at 3500 under heavy load. Changing to U0 needles sorted that problem.
I spoke with Joe Curto who told me to try WO2 needles instead of the stock CI needles, and that appears to have solved the problem. Just did this yesterday so need to do more driving, but fingers crossed!