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Engine "Run-On" Diesels #1222283 04/25/12 05:52 PM 04/25/12 05:52 PM
Joined: Jul 2007 Posts: 1,526 North Carolina cjskotni OP pro stock
cjskotni OP pro stock Joined: Jul 2007 Posts: 1,526 North Carolina	I have a small issue with my 499 stroker motor which has been a little irksome. I am going to get it professionaly tuned but for right now, I'd just like to get the bugs out of the motor so I can break the car in soon. The issue I am having is the motor, after it warms up, is that it doesn not want to idle back down all the way. If I blip the throttle or rev her up, the motor tends to setttle back down to about 850 RPM where I have the curb idle set to around 750 RPM (out of gear - auto). This problem was MUCH worse before as I had the accel pump arm a bit to tight which was holding the throttle plates from returning all the way. I adjusted this where it doesn't happen as badly but not so much where the engine goes lean when you blip the throttle. This seems to be adjusted properly now. I also shortened the return springs a tad so they pull tighter on the lever but this issue still happens just a little where it seems to not want to return to fully closed....I have also verified the butterflies aren't scrubbing on the intake manifold that I can see/feel. This wouldn't be such a huge issue except that my motor tends to "run-on" or diesel a cycle or two if cut off anywhere above 750-800RPM out of gear. The motor has only had maybe 5 hours of runtime since being built so I don't think it's carbon build-up. I am guessing maybe the motor is tending to do this becuase it's high compression (I am running 93 octane). Here are the specs on what I am dealing with: - Holley 4150 elect choke - 400>>499 4.15" stoker - Eddy Alum Heads OOB 88cc - Mopar elec ign "chrome box" - 16 deg adv base timing @ idle - motor is 10.4:1 static and 8.35:1 dynamic compression ratio Do you guys have any idea what I could do to stop this "run-on" and/or fix this throttle return issue? I am guessing they are kind of intertwined but I am a bit miffed as to what to do. I want my motor to cut off and not sound like crap when I cut er off and I want my idle to settle back to the 750 RPM out of gear. Any help or ideas are appreciated!

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222284 04/25/12 06:08 PM 04/25/12 06:08 PM
Joined: Jan 2007 Posts: 780 Woodinville, WA Viol8r super stock
Viol8r super stock Joined: Jan 2007 Posts: 780 Woodinville, WA	A few things that come to mind when I hear dieseling is: - The transition slot on the primary side of the carb is exposed too much. The way you can correct this is run more initial timing, 19-21 and thus you can close your idle screw and cover the transition. - Not enough initial timing can cause this Worst case scenario is the cam is not degreed/ installed correctly and the 16� initial is not where it seems. Last your float level should be double checked. 1968 Pro-Touring Dodge Charger *2011 Optima Ultimate Street Car Challenge Invitee http://www.popularhotrodding.com/features/1203phr_1968_dodge_charger/index.html

Re: Engine "Run-On" Diesels [Re: Viol8r] #1222285 04/25/12 06:15 PM 04/25/12 06:15 PM
Joined: Jul 2007 Posts: 1,526 North Carolina cjskotni OP pro stock
cjskotni OP pro stock Joined: Jul 2007 Posts: 1,526 North Carolina	Quote: A few things that come to mind when I hear dieseling is: - The transition slot on the primary side of the carb is exposed too much. The way you can correct this is run more initial timing, 19-21 and thus you can close your idle screw and cover the transition. - Not enough initial timing can cause this Worst case scenario is the cam is not degreed/ installed correctly and the 16� initial is not where it seems. Last your float level should be double checked. I just set the floats a few weeks ago. I have them where the fuel trickles out of the sight plugs if you rock the car while running. I might try to add some timing to it and see if that helps. I am just hoping my motor isn't beyond where pump gas will work...I know I am right on the edge with my build.

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222286 04/25/12 06:38 PM 04/25/12 06:38 PM
Joined: Apr 2010 Posts: 4,154 bethlehem pa M mikemee1331 master
mikemee1331 master M Joined: Apr 2010 Posts: 4,154 bethlehem pa	Quote: Quote: A few things that come to mind when I hear dieseling is: - The transition slot on the primary side of the carb is exposed too much. The way you can correct this is run more initial timing, 19-21 and thus you can close your idle screw and cover the transition. - Not enough initial timing can cause this Worst case scenario is the cam is not degreed/ installed correctly and the 16� initial is not where it seems. Last your float level should be double checked. I just set the floats a few weeks ago. I have them where the fuel trickles out of the sight plugs if you rock the car while running. I might try to add some timing to it and see if that helps. I am just hoping my motor isn't beyond where pump gas will work...I know I am right on the edge with my build. it could be your timing but for what ever reasons there is unburned fuel (or carbon deposits) that's being ignited by that's too hot. you may need to run a colder plug.

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222287 04/25/12 06:42 PM 04/25/12 06:42 PM
Joined: Mar 2006 Posts: 44 Canada 6 69 Dart member
69 Dart member 6 Joined: Mar 2006 Posts: 44 Canada	If you run out of ideas and are unable to fix it, you can always turn the key off "in gear". This will usually kill the motor without runon, and letting the clutch out a little with a standard trans. will accomplish the same thing.

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222288 04/25/12 06:44 PM 04/25/12 06:44 PM
Joined: Jan 2007 Posts: 780 Woodinville, WA Viol8r super stock
Viol8r super stock Joined: Jan 2007 Posts: 780 Woodinville, WA	Quote: Quote: A few things that come to mind when I hear dieseling is: - The transition slot on the primary side of the carb is exposed too much. The way you can correct this is run more initial timing, 19-21 and thus you can close your idle screw and cover the transition. - Not enough initial timing can cause this Worst case scenario is the cam is not degreed/ installed correctly and the 16� initial is not where it seems. Last your float level should be double checked. I just set the floats a few weeks ago. I have them where the fuel trickles out of the sight plugs if you rock the car while running. I might try to add some timing to it and see if that helps. I am just hoping my motor isn't beyond where pump gas will work...I know I am right on the edge with my build. Your compression is fine I run more static and dynamic with similar parts and I go 19 initial and 34 total on pump gas. What plug are you running? You should be in the 6 to 7 heat range with NGK or around 9 with Champion. 1968 Pro-Touring Dodge Charger *2011 Optima Ultimate Street Car Challenge Invitee http://www.popularhotrodding.com/features/1203phr_1968_dodge_charger/index.html

Re: Engine "Run-On" Diesels [Re: Viol8r] #1222289 04/25/12 07:35 PM 04/25/12 07:35 PM
A Anonymous Unregistered
Anonymous Unregistered A	Many times this is caused by the primary throttle blades being open too far thus uncovering too much of the slot as someone has already mentioned--The biggest reason this happens is that you are forced to open it with the idle screw to get the engine to idle and the reason for that is your distributor probably is not set right and you do not have enough initial timing--Initial timing or more of it makes muscle engines happy--If you have a Mopar Performance distributor it may have the oh so beautiful adjustable slots--pull the cap turn it while looking through the plate and if you see a torx screw say yahoo! You can back the screww out a few rounds--turn the dist 180 degress and back the other one out and then you can close the slots up to approx 1/2 of the slots length give or take tighten the screws and you have done what used to take welding, filing, and TIME to do--you now will have a ton more initial advance--thus the engine idles well with the blades closed and the other problem goes away--there is more to it--they make gauges to determine how much to close the slot to get a desired initial # but WTH --just close it approx 1/3 or more and you will be in the 16-20 degree range at idle that you can then check with your trusty timing light--THEN you must set total timing--with NO vacuum connected rev the engine until all mechanical advance is in ( again use your timing light) hold that rpm then rotate distributor until desired total ( usually 36-38 degree range) lines up with your pointer--oh yes..you need a degreed damper OR a Mopar timing tape on there before you can do this--close the blades and get it to idle by adding more initial timing--all there is to it!

Re: Engine "Run-On" Diesels [Re: Viol8r] #1222290 04/25/12 08:29 PM 04/25/12 08:29 PM
Joined: Jul 2007 Posts: 1,526 North Carolina cjskotni OP pro stock
cjskotni OP pro stock Joined: Jul 2007 Posts: 1,526 North Carolina	Quote: What plug are you running? You should be in the 6 to 7 heat range with NGK or around 9 with Champion. Champion RC12YC gapped @ .035" Would these be too hot and need to go to maybe Champion RC9YC or equiv?

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222291 04/25/12 09:33 PM 04/25/12 09:33 PM
Joined: Apr 2010 Posts: 4,154 bethlehem pa M mikemee1331 master
mikemee1331 master M Joined: Apr 2010 Posts: 4,154 bethlehem pa	i can't really say what plug to use. i'm suggesting that because you might be building up too much heat on them causing the engine to run-on. i do think for starters you could crack the plugs open to .40. that alone could cause a better and more complete burn. altering the timing some could help.

Re: Engine "Run-On" Diesels [Re: cjskotni] #1222292 04/26/12 06:08 PM 04/26/12 06:08 PM
Joined: Jan 2007 Posts: 780 Woodinville, WA Viol8r super stock
Viol8r super stock Joined: Jan 2007 Posts: 780 Woodinville, WA	Quote: Quote: What plug are you running? You should be in the 6 to 7 heat range with NGK or around 9 with Champion. Champion RC12YC gapped @ .035" Would these be too hot and need to go to maybe Champion RC9YC or equiv? I would say yes, 12 is too hot for this combination. I would try 10's for normal driving and maybe consider 9's if you take it to the track. 1968 Pro-Touring Dodge Charger *2011 Optima Ultimate Street Car Challenge Invitee http://www.popularhotrodding.com/features/1203phr_1968_dodge_charger/index.html

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