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Engine diesels on shut off? #2772767 05/09/20 09:54 AM 05/09/20 09:54 AM
Joined: Jun 2006 Posts: 88 Oregon 6 6T9RR OP member
6T9RR OP member 6 Joined: Jun 2006 Posts: 88 Oregon	I have a 383 ‘69 rr, after market cam and enlarged intake valves. It is dieseling at shut off, I have double checked the timing and it’s correct. I’ve run this motor since 2012 and resetting the timing has always cured any dieseling. I don’t know what else can cause this, any ideas are appreciated. Thank you, Paul

Re: Engine diesels on shut off? [Re: 6T9RR] #2772783 05/09/20 10:34 AM 05/09/20 10:34 AM
Joined: Aug 2006 Posts: 2,505 God's Country Maryland GODSCOUNTRY340 master
GODSCOUNTRY340 master Joined: Aug 2006 Posts: 2,505 God's Country Maryland	Usually the idle is too high, causing dieseling. I love the smell of Deer guts in the morning, it smells like... VICTORY!

Re: Engine diesels on shut off? [Re: GODSCOUNTRY340] #2772791 05/09/20 10:56 AM 05/09/20 10:56 AM
Joined: Apr 2003 Posts: 3,509 Tulsa, Oklahoma 340Cuda master
340Cuda master Joined: Apr 2003 Posts: 3,509 Tulsa, Oklahoma	Originally Posted by GODSCOUNTRY340 Usually the idle is too high, causing dieseling. I would agree. Also any chance you got a bad tank of gas. What is your compression ratio and what fuel do you run? As carbon builds up over the years octane requirement can go up.

Re: Engine diesels on shut off? [Re: GODSCOUNTRY340] #2772794 05/09/20 11:03 AM 05/09/20 11:03 AM
Joined: Jan 2003 Posts: 15,343 Omaha Ne T TJP I Live Here
TJP I Live Here T Joined: Jan 2003 Posts: 15,343 Omaha Ne	Originally Posted by GODSCOUNTRY340 Usually the idle is too high, causing dieseling. A couple of other suggestions if reducing the idle does not help. !\1. if it's an automatic, shut it off in gear. 2. if it's a stick, while in gear, turn the key off and slowly let the clutch out at the same time. Takes a little practice to get the timing of both actions to coincide for a smooth turn off www.tandmautomotive-omaha.com

Re: Engine diesels on shut off? [Re: GODSCOUNTRY340] #2772803 05/09/20 11:11 AM 05/09/20 11:11 AM
Joined: Jun 2005 Posts: 128 Troy,MI S Siba member
Siba member S Joined: Jun 2005 Posts: 128 Troy,MI	Originally Posted by GODSCOUNTRY340 Usually the idle is too high, causing dieseling. Agree! I had the same problem but my engine needed the higher idle. My fix was back down the idle on the carb (to get it back on the idle circuit) and then I increased the initial timing. Problem solved.

Re: Engine diesels on shut off? [Re: 6T9RR] #2772830 05/09/20 11:47 AM 05/09/20 11:47 AM
Joined: Feb 2014 Posts: 1,704 central il. S second 70 top fuel
second 70 top fuel S Joined: Feb 2014 Posts: 1,704 central il.	It could also be too lean. Maybe a vacuum leak.

Re: Engine diesels on shut off? [Re: 6T9RR] #2772876 05/09/20 01:37 PM 05/09/20 01:37 PM
Joined: Jul 2015 Posts: 44 Youngstown Vincenzo member
Vincenzo member Joined: Jul 2015 Posts: 44 Youngstown	What do you mean, the timing is “right” hopefully you are not timing to 1969 specs. This fuel needs a little more time to complete its burn. Woodruff Carburetor Specialties 330-799-9479

Re: Engine diesels on shut off? [Re: 340Cuda] #2772904 05/09/20 03:28 PM 05/09/20 03:28 PM
Joined: Jun 2006 Posts: 88 Oregon 6 6T9RR OP member
6T9RR OP member 6 Joined: Jun 2006 Posts: 88 Oregon	My c/r is 9.0:1 and I run 91 octane premium.

Re: Engine diesels on shut off? [Re: 6T9RR] #2772905 05/09/20 03:29 PM 05/09/20 03:29 PM
Joined: Jun 2006 Posts: 88 Oregon 6 6T9RR OP member
6T9RR OP member 6 Joined: Jun 2006 Posts: 88 Oregon	The timing is set at 10 degrees BTDC, idle is 700.

Re: Engine diesels on shut off? [Re: 6T9RR] #2772906 05/09/20 03:32 PM 05/09/20 03:32 PM
Joined: Jun 2006 Posts: 88 Oregon 6 6T9RR OP member
6T9RR OP member 6 Joined: Jun 2006 Posts: 88 Oregon	Oh, it’s a stick also. I will work on the suggestions given and respond back. Thank you to all who responded, I really appreciate it! Paul

Re: Engine diesels on shut off? [Re: 6T9RR] #2772949 05/09/20 06:12 PM 05/09/20 06:12 PM
Joined: Oct 2005 Posts: 8,869 Ontario, Canada S Stanton Don't question me!
Stanton Don't question me! S Joined: Oct 2005 Posts: 8,869 Ontario, Canada	I always wondered why my car would diesel but every race car I ever saw would shut off clean.

Re: Engine diesels on shut off? [Re: 6T9RR] #2772964 05/09/20 06:53 PM 05/09/20 06:53 PM
Joined: Jul 2015 Posts: 44 Youngstown Vincenzo member
Vincenzo member Joined: Jul 2015 Posts: 44 Youngstown	Give that thing some initial timing. It will probably respond well to 15-20 Btdc. Remember what ever you put into the bottom also goes to the top. You don’t want to be 40 total. Woodruff Carburetor Specialties 330-799-9479

Re: Engine diesels on shut off? [Re: Stanton] #2772981 05/09/20 07:50 PM 05/09/20 07:50 PM
Joined: Mar 2011 Posts: 3,074 Michigan A A727Tflite master
A727Tflite master A Joined: Mar 2011 Posts: 3,074 Michigan	Originally Posted by Stanton I always wondered why my car would diesel but every race car I ever saw would shut off clean. I wonder too.

Re: Engine diesels on shut off? [Re: 6T9RR] #2773017 05/09/20 10:41 PM 05/09/20 10:41 PM
Joined: Dec 2009 Posts: 20,640 in a cattle trailer down by th... G Guitar Jones Paddle faster! I hear banjo music!
Guitar Jones Paddle faster! I hear banjo music! G Joined: Dec 2009 Posts: 20,640 in a cattle trailer down by th...	The combustion chamber temperature is too high and that can cause carbon in the cylinder to glow and continue to ignite fuel. This used to be quite a problem in the late 70's and early 80's when manufacturers where trying all kinds of things to get their engines to meet emmisions. Crappy fuel that ignites easily, too high of an idle speed, a carb problem, too much or too little ignition timing can all contribute to the condition as well as an escalated engine coolant temperature. "Follow me the wise man said, but he walked behind" '92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion. '74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon! 2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.

Re: Engine diesels on shut off? [Re: Guitar Jones] #2773079 05/10/20 08:21 AM 05/10/20 08:21 AM
Joined: Jan 2003 Posts: 8,668 Buford, GA I_bleed_MOPAR master
I_bleed_MOPAR master Joined: Jan 2003 Posts: 8,668 Buford, GA	Originally Posted by Guitar Jones The combustion chamber temperature is too high and that can cause carbon in the cylinder to glow and continue to ignite fuel. This used to be quite a problem in the late 70's and early 80's when manufacturers where trying all kinds of things to get their engines to meet emmisions. Crappy fuel that ignites easily, too high of an idle speed, a carb problem, too much or too little ignition timing can all contribute to the condition as well as an escalated engine coolant temperature. Exactly why manufacturers used idle solenoids. For the younger guys (and gals), you would set the idle speed to spec with the solenoid. Then when you shut the engine off, the solenoid allowed the throttle blades to close. Tim '71 Charger 383/727 '17 Challenger SXT (Wifeys car )

Re: Engine diesels on shut off? [Re: GODSCOUNTRY340] #2773081 05/10/20 08:31 AM 05/10/20 08:31 AM
Joined: Jan 2003 Posts: 1,013 LEE, MASS T TOMRR super stock
TOMRR super stock T Joined: Jan 2003 Posts: 1,013 LEE, MASS	[]Usually the idle is too high, causing dieseling. That's what cure my 440 I set it at 900 rpm

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