"dieseling" '75 d200 345

[76 xlc]

For the '67 model year, VW added an electric fuel shut off solenoid to avoid run-on, after retarding timing and leaning the mixture, two things IC engines don't like, especially air cooled IC, to meet US smog regs.

Does the oxygenated fuel of today create a similar situation on old IHC IC engines?

[Jay Tabor]

fibre optic scope stuck in the sp hole will show before and after carbone removal.

fm house; am well aware of supposed timing causing dieseling, its a secondary cause.
the real cause is too much fuel in the comb. chamber./
and that points directly at the owner/operator/driver.
i can, with my excellent- running- well -tuned- IH- torque- monster- v8- 304 engine easily get the engine to diesel, by romping on the throttle as i turn off the engine. its not got a hot spot in the chamber, or way off timing- or a hot running engine...........
ITS GOT A LOT OF FUEL IN THE CHAMBER. so itll do what its supposed to do - ignite and burn.
makes the engine spin forwards or backwards as the case maybe..

case closed.

[FMhouse]

Originally Posted by Jay Tabor

fibre optic scope stuck in the sp hole will show before and after carbone removal.

fm house; am well aware of supposed timing causing dieseling, its a secondary cause.
the real cause is too much fuel in the comb. chamber./
and that points directly at the owner/operator/driver.
i can, with my excellent- running- well -tuned- IH- torque- monster- v8- 304 engine easily get the engine to diesel, by romping on the throttle as i turn off the engine. its not got a hot spot in the chamber, or way off timing- or a hot running engine...........
ITS GOT A LOT OF FUEL IN THE CHAMBER. so itll do what its supposed to do - ignite and burn.
makes the engine spin forwards or backwards as the case maybe..

case closed.

that was exactly my point.Retarded timing=too much throttle to maintain idle speed=too much fuel in the chamber on shutdown.cheers.

[BO185]

Originally Posted by Jay Tabor

fibre optic scope stuck in the sp hole will show before and after carbone removal.

Dang that's a good idea. I seen one a lowes or home depot it was affordable and pretty nice color picture.

I have to look for one be nice to add to the tool box.

[Jay Tabor]

''''''''that was exactly my point.Retarded timing=too much throttle to maintain idle speed=too much fuel in the chamber on shutdown.cheers. ''''''''''''



the more i think about it, i'll disagree. easy enough to test anyways.
go twist the dist so the timing is 15 atc. see if it runs at all.
try10 atc,
try 5atc
without adjusting the idle speed..
even adjusting the idle speed screw to get it at 700, i doubt that tosses enough fuel into the intake to cause dieseling..

friday morning myth busters:
so i ,with engine fully warmed, at operating temps 185*f [on autometer mechanical temp gauge, double checked temp with 2 other thermometers in the radiator].
i checked my engine timing- 10*btdc idle speed 800rpm+-, then
i twisted the distributor ['dizzy' for you backwoods] as far as it would go to retard the timing- checked and saw the timing mark on harmonica balancer about 30 to 40 atc [ quarter past the 0* mark on the timing cover][ thats at 3 oclock position if looking at the engine from the front]
engine still ran- at about 400rpm+_ [didnt bother checking idle speed with a tacometer, I can tell by the sound, being experienced and all...]
, turned it off twice-- no dieseling ,wonder why. its supposed to!!
stepped on the gas pedal as i turned it off- no dieseling.
didnt need to turn the carburetor idle speed screw any to keep it running,
put timing back to the real world [where any IH owner would check at least once since they rescued it from a farmers field back in 1910..]
and as i turned off the ignition, I held the throttle down [ my holley squirts fuel just fine thank you very much] and as the engine stopped it gave a tiny attempt to keep running.. kinda . . did deisel.= lotsa extree fuel!

so that disolves another old wives tale into thin air, about idle speed screw turned all the way in to keep an out of time engine running.
causing any dieseling because of timing . .
[ this of course was tested on a well tuned 304IHV8 engine with 400,000 miles on it, vacuum gauge indicates 19"hg at 800rpm- idle speed, smooth needle, 10 * btdc [initial] static timing, with a -------WAIT NOW!! HOLLEY 500CFM 4412 LIST carburetor..]
your tests may vary of course..
oh with a holley electronic ignition distributor, with ford duraspark cap'rotor conversion,
jacobs wires energy core sp wires all routed seperately in wire looms to the plugs,
autolite 85 plugs, .050 gap,
and 87 octane fuel,
27.7 inches of pressure, 3000 msl, 10% humidity, 75*f.
45 psi in the BFG -AT KO 31.10.50x 15 tires load range C

[hacri]

I'm not quite sure about the fuel in the combustinon chamber.....in the old WW2 2.5t GMC(cckv) trucks the manual say to floor the gas pedal as you stop the engine, this to leave gas in the combustion chamber for easyer starts. It has to do with combustion chamber temperature, as the spark plug is not firing, but it is a self combustion(as is "pinging")