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Re: Small block diesels when I turn the key off
[Re: VITC_GTX]
#1298858
09/07/12 01:52 AM
09/07/12 01:52 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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Usually too much idle rpm or initial advance. What octane are you using?
Did you have to open the throttle too far to get it to idle?
**Photobucket sucks**
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Re: Small block diesels when I turn the key off
[Re: VITC_GTX]
#1298860
09/07/12 02:38 AM
09/07/12 02:38 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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You say there's no detonation but that it's dieseling? I bet it is detonating but you can't hear it. I run my 5.9 with 93 octane. My cam is a little smaller, at 222/228, on a 107lsa, but I'm also running thinner than stock head gaskets and have heads shaved .030 to bump compression to 9.5.
I'd consider at a minimum to try 89 octane and see if it makes a change.
**Photobucket sucks**
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Re: Small block diesels when I turn the key off
[Re: VITC_GTX]
#1298862
09/07/12 08:09 AM
09/07/12 08:09 AM
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Joined: Jul 2008
Posts: 259
Khemi, Stygia
Mebsuta
enthusiast
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enthusiast
Joined: Jul 2008
Posts: 259
Khemi, Stygia
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My RR does that with 89 octane. Have to use 91 or 93.
68 Roadrunner. 383 4-spd. Beat up.
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Re: Small block diesels when I turn the key off
[Re: VITC_GTX]
#1298863
09/07/12 08:18 AM
09/07/12 08:18 AM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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I would suggest the higher octane or a colder spark plug.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Small block diesels when I turn the key off
[Re: kilroy]
#1298870
09/07/12 11:41 PM
09/07/12 11:41 PM
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Joined: Mar 2005
Posts: 862
Iowa State fan
kilroy
super stock
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super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
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Of course increasing intial timing will then lead to the distbutor needing to have total timing limited to stop the pinging/detonation....  or the use of the afore mentioned idle solenoid.
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
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Re: Small block diesels when I turn the key off
[Re: kilroy]
#1298871
09/07/12 11:50 PM
09/07/12 11:50 PM
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Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
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Quote:
Timing is not an issue when the key is off. There is no timing involved. THERE IS NO SPARK when the KEY IS OFF!!! REPEAT THE IGNITION SYSTEM IS DEAD WHEN THE KEY IS OFF. Its caused by to much air/fuel hitting hotspots in the chambers and combusting. The air/fuel excess is caused usually by the throttle blades being opened to far in an attempt to bring the idle speed up so the engine wont stall. This usually needs to be counteracted by (contrary to what most everyone here is saying) increasing, YES, INCREASING initial timing so that idle speed is brought up and throttle blades in the carb CLOSED down to stop a surge of fuel being pulled in at idle. Or by using an idle solenoid which releases/retracts when the power is off, there by allowing the throttle blades to close cutting off the air flow, there-by stoping any vacuum signal to the carb and stoping the fuel flow. 
In my best sarcastic voice...
So what you're saying is it's the not timing, but, the timing!!! 
I vaguely remembering writing the same type of suggestion recently. The timing settings have a lot to do with this.
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Re: Small block diesels when I turn the key off
[Re: kilroy]
#1298872
09/07/12 11:51 PM
09/07/12 11:51 PM
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Joined: Jan 2005
Posts: 3,344
Central TX
roe
master
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master
Joined: Jan 2005
Posts: 3,344
Central TX
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My 360 did that on 87 octane. Stepped up to 93 with no other changes and it stopped
1971 Plymouth Satellite
408/904 8 3/4 3.23 SG
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Re: Small block diesels when I turn the key off
[Re: kilroy]
#1298873
09/07/12 11:59 PM
09/07/12 11:59 PM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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Quote:
Timing is not an issue when the key is off. There is no timing involved. THERE IS NO SPARK when the KEY IS OFF!!! REPEAT THE IGNITION SYSTEM IS DEAD WHEN THE KEY IS OFF. Its caused by to much air/fuel hitting hotspots in the chambers and combusting. The air/fuel excess is caused usually by the throttle blades being opened to far in an attempt to bring the idle speed up so the engine wont stall. This usually needs to be counteracted by (contrary to what most everyone here is saying) increasing, YES, INCREASING initial timing so that idle speed is brought up and throttle blades in the carb CLOSED down to stop a surge of fuel being pulled in at idle. Or by using an idle solenoid which releases/retracts when the power is off, there by allowing the throttle blades to close cutting off the air flow, there-by stoping any vacuum signal to the carb and stoping the fuel flow.
Do me a favor, re-read what I said.
You are absolutely correct, when you turn the key off, the SPARK PLUGS STOP FIRING. so once the key is off, spark advance from the timing has NOTHING to do with run-on.
but, if the engine is running too hot and has hot spots in the chamber because the timing is TOO FAR ADVANCED, (admit it, if the timing is too far advanced, you're creating more heat than you need to be, and the engine will run hotter) then even if the throttle plates are completely closed, the engine can still diesel.
does the idle circuit not pull in fuel and air? I think the answer is yes, it does....otherwise, the engine would never idle even with the key on.
retarding the timing a few degrees can make the engine run cooler and stop the dieseling. --it will also hurt performance though, so another solution is to run a higher octane fuel, with more resistance to detonation, which can stop the dieseling.
again, go back and read my post that got you all fired up. 
**Photobucket sucks**
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Re: Small block diesels when I turn the key off
[Re: Cab_Burge]
#1298875
09/08/12 02:30 PM
09/08/12 02:30 PM
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Joined: Mar 2005
Posts: 862
Iowa State fan
kilroy
super stock
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super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
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No I agree with the statement of hot spots, BUT, TO MUCH FUEL is the problem. Yes you pull fuel through the idle circuits BUT, again most of this is caused by the throttle blades being open to far up the transition slots in the throttle plate or even so far that the carb is even running on the main circuits which will pull, again, TO MUCH FUEL at idle causing said dieseling. The proper idle adjustment would be to take carb off and set front throttle blades so that transition slots are square or just over, than start INCREASING base timing somewhere in the neighbor hood of 13*-22* till the thing idles well. This will also clean up the idle emissions and help off idle hesitations. ITS ALL RELATIVE TO THE THROTTLE PLATE OPENINGS. This can also be caused if the rear butterflies are open to much. Just trying to help people tune their cars properly.
IT almost always because we all like our cams to rumble which causes us to open up the idle screw to make it idle which exposes these much misunderstood transition slot and then the motor just pulls way to much fuel all the time.
Last edited by kilroy; 09/08/12 02:33 PM.
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
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back the timing up a few degrees. 
I have to do that with my pump gas street motor that has 10.78 to 1 comp. artio at the track after a run, leave it in gear and shut it off 
