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02-03-2014, 07:36 PM
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#1 |
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Registered User
Join Date: Oct 2013
Location: Seattle, WA
Posts: 19
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A run on question
Hi Gang,
I have a new HP Vortec crate motor I just put in my 72 C20. The old 400 had a run on issue. I just figured it was from carbon on the heads. It had a HEI distributor. The new motor I used a HEI again. The problem is I still have a run on issue. I put a diode on the 4th terminal of my voltage regulator, however this did not solve the problem. Is it possible to insert the diode on the feed wire to the distributor and solve the issue? TinTop |
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02-03-2014, 07:55 PM
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#2 |
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Registered User
Join Date: Jul 2012
Location: Jonestown, TX
Posts: 471
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Re: A run on question
You'll have to forgive me - just trying to educate myself, but what do you mean by a run-on issue? Like dieseling/keeps running after you shut it off?
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02-03-2014, 08:14 PM
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#3 |
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Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,147
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Re: A run on question
What is your idle RPM? Run on is almost always cause by to high an idle.
__________________
1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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02-03-2014, 09:40 PM
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#4 |
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Registered User
 
Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: A run on question
Does it run just like the key is on or does sound like it's dieseling?
Dieseling can be fast idle or advanced timing. If it runs like the key is on, where are you getting your 12v run voltage from?
__________________
1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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02-04-2014, 01:27 AM
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#5 |
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Registered User
Join Date: Sep 2013
Location: iredell county, nc
Posts: 77
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Re: A run on question
Try unplugging the + wire from the distributor, if it cuts off like it should it is something in your wiring.
If it still has a run on it could be timing, idle speed, or you need a higher octane fuel
__________________
Real trucks have a clutch. Please inform automakers.  1972 GMC, K25, 383 stroker, SM465, NP205, Eaton HO-72 |
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02-04-2014, 01:12 PM
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#6 |
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Registered User
Join Date: Oct 2013
Location: Seattle, WA
Posts: 19
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Re: A run on question
The Idle could be a bit high, the timing is spot on.
I'll lower the idle and see where that gets me. |
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02-04-2014, 01:42 PM
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#7 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,731
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Re: A run on question
What do you mean the timing is spot on?
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03-05-2014, 08:24 PM
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#8 | |
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Registered User
Join Date: Dec 2012
Location: Providence, RI
Posts: 211
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Re: A run on question
Quote:
Also on the run-on, AC trucks the idle is set a bit higher than none AC trucks, and they have an anti diesel switch to help shut the truck off faster. If that switch is not working, it "could" be your problem. On mine, once I kill the ignition, the AC compressor kicks on and puts an added load on the motor helping it to stop faster. Once the engine stops, I can hear the compressor click off
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Mark 71 C10 Cheyenne 12 Aprilia RSV4 |
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03-06-2014, 11:47 AM
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#9 |
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Registered User
Join Date: Sep 2011
Location: Wildrose, North Dakota
Posts: 300
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Re: A run on question
Well you may run on for a long time
run on for a long time Sorry for the lyrics. They just came to mind. :P In my experience run on has been caused by higher than regular idle rpm at shutdown.
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Dane 67 Chevy Fleet 250/4 speed 1/2 ton 68 Chevy 250/4 speed 1/2 ton for parts 49 GMC Grain truck 235 1 1/2 ton 76 Chevy 350/4 speed 1/2 ton |
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