When shutting truck off...

[highdesertrange]

most common cause for dieseling is to high of idle. highdesertranger

 

[lusktommy]

I've had backfire for to high of an idle. Lol in lowes hardware parking lot. Lady screamed across the parking lmao

 

[Edhard_Stark]

So as for the high idle/dieseling on my end, I throw the truck in park, and it high idles. I then disconnect the vacuum line going to the vacuum advance on the distributor and the idle goes back down to normal. Bad vacuum advance? Do I have to replace the whole dis.? Sorry but the old school engines are new to me, I have yet to fully tinker with one.

 

[mtnmankev]

So as for the high idle/dieseling on my end, I throw the truck in park, and it high idles. I then disconnect the vacuum line going to the vacuum advance on the distributor and the idle goes back down to normal. Bad vacuum advance? Do I have to replace the whole dis.? Sorry but the old school engines are new to me, I have yet to fully tinker with one.

What is your initial timing set at, with the vacuum advance disconnected and vacuum line plugged?

 

[350runner]

Sounds like you have too much vac advance.

 

[Edhard_Stark]

8 degrees. However I should mention that the engine in my 79 is a center bolt engine from the late 80's, I don't know if that matters or not. Also, the vacuum advance and the vacuum line from the transmission go into a tee fitting, and both of those lines are drawn in through the single vacuum hookup in the front of my Edelbrock. I was told that I should have the trans portion plugged into the port on the intake. I don't know if that matters either.

 

[350runner]

You can go ported as a quick fix out or figure out how much vac advance you have and limit it via stop plate

 

[Edhard_Stark]

Go ported? What does that mean? How can I check how much advance I have? What's a stop plate, and how would I adjust it? Sorry, I'm new at these distributors and carbs.

 

[mtnmankev]

Ported vacuum only has suction when the throttle is opened.
At idle with hose disconnected, you won't feel any vacuum at the fitting.
Most carburetors have several ported vacuum fittings.

 

[Edhard_Stark]

Ok I'll look into that. Any input for checking the dis.?

 

[350runner]

This^^^ and here is a simple way to limit the amount of vacuum advance. http://m.summitracing.com/parts/crn-99619-1
Also here is timing tape if you do not have a timing gun with a dial. http://m.summitracing.com/parts/msd-8985
Use this, or just set the timing with the engine on to 0° btdc then count the degrees of vac advance.

 

[Edhard_Stark]

Cool thanks guys. Should I mention that this happens when the engine gets up to operating temperature? When I drive around while the engine's cold, it's fine, but at operating temp it has this symptom.

 

[350runner]

8dbtc really ain't much and could prob have more... but limiting the vac advance is key and this and detonation is why I will never suggest someone just hook up the vac advance not knowing how much advance it provides and where they are all in timing wise.

 

[lusktommy]

Hey my Cummins 5.9 has a dieseling problem should I be concerned about this? ? Hehe

 

[350runner]

Yes very lol. If it can't tow it must go! Haaaa!