Dieseling

My experiences with dieseling were usually ratified by using manifold vacuum for the vacuum advance, which increases the timing at idle and allows you to close the throttle blades while still maintaining spec idle rpm. Having the throttle blades open too far allows enough air into the engine to keep it running on.
Do you suspect there might be carbon in the combustion chambers?
Have you changed brands or grades of gasoline lately?
 
So, two webers, M30 engine, auto trans. Dieseling. Hmmm. have had the very same with my '72 CSA. Annoying. So, just my experience, ("your mileage may vary", sort of advice) but, first step, I made certain timing was spot on, all plugs at least clean and proper gap, perfect distributor cap and rotor, trusted plug wires, webers taken down to initial setup, inspect linkage and be certain everything is free and operates the same for each carb. Don't be afraid to adjust rods and all linkage operations to be sure each carb operates as the other. Tune when fully warmed up. Auto trans especially sensitive as it "costs" at least a couple 100 RPMs when out of gear. Experiment, play with idle adjustment screws in identical increments. I can get mine down to about 550 rpm at a stoplight, and still in "gear". When out of gear, (Neutral or Park), of course RPMs increase and if they exceed 1000 you will definitely get run-on. Takes some patience, but can be sorted. Just make sure you are working with clean slate. Ignition variables must be nailed down, then you can work the fuel mix and idle. Good luck! Mike
 
Your alternator may be backfeeding into your ignition circuit
You can't turn your ignition off.
 
thanks guys, after getting info from you guys and putting everything to test I found out its the fuel!
Started using 93 octane gas and that has taken care of the problem so far. Thanks Mike, Mike, Viphoto, Chris, Steve and Don
 
Hey that's great. Always nice to hear of a resolution. But mark my words...you will be back! LOL. Higher octane fuel helps a lot, but I think that is just a clue that you may be on the edge of tune. Whenever you have more time and as you move down your list of "to-do's" you may revisit and really dial ignition and fuel systems in and optimize performance. Mike
 
Thanks Mike, I am thinking combustion chambers may have carbon build up, since the car is tuned and carbs are adjusted. Hope the high octane gas will take care of it and I do not have to pull the head off!
 
A gallon of water and six feet of vacuum line will get rid of the carbon.
Takes about an hour and 50 miles.
 
Drive down the careterra at Cien km
Es mejor que nadia esta por atras!
Cada minuto ponga la manguera in la bottella de agua por cinco segundos.
Usted puede ver por la ventana cuando todo es limpia.
 
Ha ha Don. that real old school combustion clean up. we used to do a quicky 20 min job on 320's as part of major services at the dealership that I worked at back when 320's were new Sure made lots of smoke when we did it because we did not go for a drive, just did it in the parking lot, loved doing it when salesmen were around, used to freak them out but it did work

Thanks, Rick
 
sfdon said:
Drive down the careterra at Cien km
Es mejor que nadia esta por atras!
Cada minuto ponga la manguera in la bottella de agua por cinco segundos.
Usted puede ver por la ventana cuando todo es limpia.
Click to expand...

no puedo creer lo que me esta usted contando
increíble, ¿ esta usted seguro que no producirá daños en el motor ?
muchas gracias por compartir su truco conmigo
;-)
 
stphers said:
Ha ha Don. that real old school combustion clean up. we used to do a quicky 20 min job on 320's as part of major services at the dealership that I worked at back when 320's were new Sure made lots of smoke when we did it because we did not go for a drive, just did it in the parking lot, loved doing it when salesmen were around, used to freak them out but it did work

Thanks, Rick
Click to expand...
Hey Rick, is that anything like the Seafoam "treatment" some drivers would pour into some vacuum port when they failed an emissions test? Also produced tons of smoke, and though it was "guaranteed" to help you pass next test, many times test yielded same result : "Fail". ask me how I know! OK... was my son's mega mile E36. We are over that now. Nothing like a new catalytic converter, muffler and O2 sensors to help register clean numbers. Mike
 
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