383 diesling

[sleepychallenger]

i have tried re timing it, need to put points in there, would that cause it to diesle? my timing is set to what the factory sticker says 2 1/2 BTDC. i have tried advancing it, no help, tried retarding it, no help, the only time that it doesnt diesle when i shut it off is if i run premium gas, but that gets really pricey really quick. any ideas??? 

[asm74]

Is this a basically stock 383?  Do you know what the compression ratio is?

[sleepychallenger]

ummm, i just know that we have the 10:1 flat tops in it, a hemi grind cam, .030 overbore. other than that it is stock

[Jacksboys]

ummm, i just know that we have the 10:1 flat tops in it, a hemi grind cam, .030 overbore. other than that it is stock

10:1 with iron heads?  that is a lot of compression for 89 octane
Yep you need to run 93 octane, I bet that is your only problem.

[Chryco Psycho]

reasons for dieseling
- high idle speed
- rich mixture
- incorrect timing
- heat , engine temp or spark plug temp / heat range
- carboned combustion chambers
1 or more of these will be the cause & as stated above if you really have 10:1 compression premium is a must

[sleepychallenger]

10:1 with iron heads?  that is a lot of compression for 89 octane
Yep you need to run 93 octane, I bet that is your only problem.

it never did it before i put in the bigger cam. the cam was put in at no advace or retard, just 0. my timing is at 2 1/2 BTDC. the 10:1 is the pistons that my dad ordered when we redid the engine about 8 years ago. the engine does always run hot, cant get it to cool off. i dont have a fan shroud and cant find one for my car but wouldnt think that it would make it run that much hotter when cruising down the highway or running on a cold day.

[pink panther]

I'd say run premium 93 octane and it should help, I even add octane booster to mine.

[sleepychallenger]

ok, i guess it will save me in the long run over a couple of dollars right now. it did deisle a little sometimes with premium though, only like the first tank after changing between reg to prem. any more ideas?

[ShelbyDogg]

Look at Chryco's suggestions. 
Your Throttle is not closing enough when you shut off the engine or your power valves are leaking. loosen the idle screw where you have to hold it open for it to idle, then shut it off and let go of the throttle at the same time.  Does it still run on?

[sleepychallenger]

i will have to try that. everything in the carb is new. i havent driven the car in about 2 weeks now.

[MEK-Dangerfield]

it never did it before i put in the bigger cam. the cam was put in at no advace or retard, just 0. my timing is at 2 1/2 BTDC. the 10:1 is the pistons that my dad ordered when we redid the engine about 8 years ago. the engine does always run hot, cant get it to cool off. i dont have a fan shroud and cant find one for my car but wouldnt think that it would make it run that much hotter when cruising down the highway or running on a cold day.

First off, with a bigger cam, I'm guessing your timing is way off here. It should be more advanced, and YES, you will need 93 octane gas. A fan shroud does more than you think. Without one, the fan is sucking air from everywhere, when it should just be sucking the heat away from the radiator. Just curious, do you have a 22", or 26" radiator?


   Mike

[sleepychallenger]

22"

shouldnt the timing be set ok if i set the cam at 0?

[MEK-Dangerfield]

22"

shouldnt the timing be set ok if i set the cam at 0?

2.5 degrees BTDC just sounds bad to me. Are you up for an experiment? Put your timing light back on, and slowly advance the timing while you are at idle. If the idle picks up speed, then your timing is probably retarded too much.


  Mike

[Bullitt-]

quote from Hotrod Mag (same thing CP has been telling everyone)
The "hot rod advance curve" used mostly on a 9:1 engine with a mild camshaft (duration less than 220 degrees at 0.050-inch of valve lift) is 10 to 12 degrees initial timing plus 22 to 24 degrees of additional advance from the mechanical advance mechanism
read it all http://www.rodandcustommagazine.com/techarticles/0604rc_ignition_timing/

[sleepychallenger]

i will have to do all of this on saturday. the 2.5 is just off the decal on the drivers side inner fender.

i did increase the timing to 8 btdc and it didnt make any difference, maybe 12 will.