Engine dieseling

LAR, SOMETIMES, I HAVE FOUND THAT TO HIGH OF AN IDLE SETTING, AS IN THE THROTTLE BLADES BEING OPEN TO FAR, WILL CAUSE "RUN-ON" DEISELING. AS WELL AS RUNNING HOT TEMP, OR AS YOU SAID, TIMING WILL BE AT FAULT. YOU MIGHT FIRST TRY CUTTING BACK ON THE IDLE SPEED. SAY IF YOUR AT 900-1000 RPM, TRY 700-800 RPM. I'AM ALSO ASSUMING, LIKE THE REST OF US, YOU ARE RUNNING AT LEAST 91 OCTANE. THIS IS ALSO WHY IT IS IMPORTANT TO POLISH OFF ALL OF THE SHARP EDGES WITH-IN THE COMBUSTION CHAMBER WHEN WE GET THE CHANCE! MINE WILL RUN-ON FOR 15-20 SECONDS AFTER I SHUT THE KEY COMPLETELY OFF!! BUT THAT IS CAUSED FROM "RESIDUAL" ELICTRICAL CURRENT WITH-IN THE IGNITION CURCUIT! GOOD-LUCK! MARLIN.

[This message has been edited by MARLIN JACK (edited 06-29-2002).]

Marlin:I was going to say the exact same thing

Marlin and RC
Thank you both and you hit it right on the head. I am running a 750 Holley with a mech. choke that is not hooked up. When the car is cold it wants to idle and then die @ 600 rpm. When its warm it want to run @1200 rpm. I did have a residual electric charge from the fan motors, but we put a kill switch on one side and its okay now, in that regards..The timing marker has been removed(?) and we need to work around that with a dyno shop. The car has been in paint and upholstery for the last 4 months and I just got it back. I have many more things to sort out, but with help from you guys and a lot more patience than I have things will be okay. Thanks Again
Lar

I would set the idle speed with the engine warm and just live with it cold.You will have to keep it running until it warms up but it dosn't take long.Small price to pay if you ask me.

LAR! I JUST REREAD YOU STATEMENT!! YOU NEED TO GET YOUR MECHANICAL CHOKE HOOKED BACK UP, THEN YOU WILL HAVE EASY STARTING WHEN COLD, WHEN WARMED UP AND YOU SLIDE THE CHOKE OFF, YOU WILL BE IDLEING PERFECT!!(ONCE YOU SET THE IDLE WHILE WARMED UP!) THEN SINCE YOUR BUTTERFLIES WILL NO LONGER BE OPENED TOO FAR IN ORDER TO IDLE THE ENGINE IN THE COLD,(BECAUSE YOU DO NOT HAVE A CHOKE), IT WILL SHUT OFF "RIGHT NOW" WHEN THE KEY IS TURNED OFF! I THINK THAT SOLVES YOUR PROBLEM, YOU MUST HAVE A CHOKE! YOU HAD YOUR THROTTLE OPENED WAY UP TO COMPENSATE FOR THE LACK OF A CHOKE. MARLIN.

[This message has been edited by MARLIN JACK (edited 06-29-2002).]

[This message has been edited by MARLIN JACK (edited 06-29-2002).]

[This message has been edited by MARLIN JACK (edited 06-29-2002).]

.Hi Rmccall,
I agree with you, set idle speed warm, live with it when cold. Either wire the choke open or remove it completely. Next get out your vacuum gauge and set your mixture screws to max vacuum for the desired RPM, HOT ONLY! This should give acceptable idle don't be afraid to play with this, especially closing the mixture screws and opening the throttle plates.
Good Luck, Guy
PS As you are fooling around with all of this, MAKE SURE that you
set the accelerator pump linkage to "0" clearance every time you change the throttle plate position

As you probably know, Holley sells a bolt-on electric choke assembly that fits all 4bbl models (for an extra $37 or so) and only takes a single key-switched hot wire to actuate. But do NOT take the easy way out & hook it to the hot wire to the coil! Doing so will allow the choke to work just fine but will pull enough amperage to drop coil voltage & act as a rev-limiter, usually around 4500 rpms. This is one of the most common electrical screw-ups we see at tech sessions. This should fix your starting problem. The dieseling likely comes from the requirement for a very rich mixture to start an engine, and the rich mixture builds up carbon in the combustion chamber.

if i recall corretly ford hooks the choke power to the stator wire off the alternator.

quote:

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Originally posted by mikep01:
if i recall corretly ford hooks the choke power to the stator wire off the alternator.

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YES! YOU ARE MOST CORRECT. IN THE CASE OF AN ELECTRIC CHOKE, IT IS HOOKED TO THE "STATER" WIRE, MARKED "STA" ON THE BACK OF THE ALTERNATER AND "S" AT THE 'EXTERNAL' VOLTAGE REGULATER. IN THE "BOOK" THIS ONLY SHOWS IT AS WIRED TO A STOCK ALTERNATER WITH AN EXTERNAL REGULATER! GOOD-LUCK, MARLIN.

[This message has been edited by MARLIN JACK (edited 07-02-2002).]