timing falls off under a load, but not in Neutral

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Apr 2, 2009 | 01:54 PM

68camperspecial

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timing falls off under a load, but not in Neutral

Ok, I have a 68 3/4 ton with a 318 and a 2 bbl carb. the engine revs up fine in neutral, but when I put it in reverse or drive gears, I have to feather the gas constantly or it stalls out. The timing is just right when I have it in neutral, but it fails to advance properly when under a load.

So far I have replaced every vacuum line i could find in addition to some detective work around the intake manifold gaskets and such with the spray and listen technique. I also removed the vacuum advance unit and checked it for leaks.

Any thoughts?

Apr 2, 2009 | 02:20 PM

78D200

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Joined: Apr 2008

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From: Goffstown, NH

When you set the timing, did you do it with the vacuum advance hooked up or disconnected and plugged? Have you done any upgrades or replaced any other parts besides the vacuum lines as of late? Have you made any adjustments to the carb?

Apr 2, 2009 | 05:05 PM

richinny

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have you checked the advance with a timing light?

Apr 2, 2009 | 08:02 PM

craveman

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Joined: Feb 2009

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From: st. johnsville, NY

i dont think the vaccum advance would be making it stall that much. when i went to steam clean my engine today i noticed that i forgot to hook the vaccum line up when i had it off last about 2 days ago and it ran the same as normal. well normal for my car. the carb is bad and on an air fuel guage it runs at 7.2 on one bank and 6.7 on the other. In case you didnt know optimal is 14.6 to 1 and the richest an engine will actually run is about 5.0

Apr 4, 2009 | 09:46 AM

cudaneil

Mopar Fan

Joined: Nov 2008

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From: cheshire,england. UK

Sounds like a points and condenser fault ! Do you have them ? A bad condenser will make it do that.

Last edited by cudaneil; Apr 4, 2009 at 09:49 AM.

Apr 9, 2009 | 08:32 AM

68camperspecial

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I checked the timing with A light and it advances properly in Neut. but not in Drive or Rev. the only changes i made recently were spark plugs and wires, vacuum lines, and brakes. when i checked the timing, I disconnected the Vac advance and plugged it. I am now thinking that it is the points and condenser, I'll post again after that. I haven't changed the distributor guts since i got the truck last summer and I'm sure they need to be changed regardless. thanks for the tips.

-Jim