[64speed]

Just want to make sure it won’t hurt anything

[Kenth]

Originally Posted by steve25

And the above move of having your vacuum advance active at idle will require one to recurve the Distributor.

Absolutely NOT necessary.
The only difference is full timing at idle speed and coasting. While driving it´s all the same curve.

[Formulajones]

Vacuum advance active at idle won't hurt anything, If the distributor is dialed correctly to begin with.

For example, a typical 12 or 14 initial setting, along with a vacuum advance modified to allow 10-12 degrees, would work perfectly fine at idle and won't cause any dieseling. That's only 20-26 degrees at idle, and I've dealt with engines with more than that.
In fact it would likely help dieseling because you would be able to close the throttle blades more for a base idle setting, and from what I've seen in changes on running temp, it would likely keep the combustion chambers cooler with the added timing, another plus in more than one way. One thing that isn't helping your issue are those hot running temps you posted earlier. Todays fuel just doesn't like that much at all.

Does an engine always need the added timing? No, but with todays fuels sometimes we have to stray from what used to be considered the norm. There is no set answer. Experiment with some different tuning variables and see how the engine responds. This is something that can't be done on a dyno. It takes a bunch of time and driving many miles putting the car in different scenarios to find what works the best. Ideally you don't want dieseling, you want easy starts that don't require playing with the throttle for 5 minutes until it idles, and you don't want heat soaked hot start issues that make the car a pain to drive for the first several minutes. You want your wife to be able to jump in the car and run errands without all that monkey business going on. That's what I strive for. With enough time spent on the tune you can accomplish all those things and make the car run like a new one.

[HWYSTR455]

More timing at idle burns a leaner mixture, if the mixture is lean enough there is no fuel to cause run-on. It's that simple.


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[64speed]

I lowered the idle (a little too much) and it’s not doing it so I think I have to find a happy medium.

[dataway]

If the engine has spent a lot of time idling .... throw some SeaFoam fuel treatment in it. I'm usually not a fan of such products ... but when my Cub Cadet V-twin started dieseling badly someone suggested it was a carbon hot spot and the SeaFoam would cure it ... sure enough it did, things shuts down perfect now.

[HWYSTR455]

It's a fresh build.


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[dataway]

I was kind of thinking even a fresh engine could load up from idling, even more than a engine with nicely seated rings. Messing around with carb and timing trying to sort things out can lead to less than optimal conditions in the combustion chamber .... at least when I'm doing the tuning

[george kujanski]

Getting it idle with minimum throttle opening is the key. Back in the day they used a throttle stop solenoid that kept the throttle at idle. When you shut off the ign, the solenoid dropped out letting the throttle close.more fully.

George

[HWYSTR455]

Originally Posted by george kujanski

Getting it idle with minimum throttle opening is the key. Back in the day they used a throttle stop solenoid that kept the throttle at idle. When you shut off the ign, the solenoid dropped out letting the throttle close.more fully.

George

Refer to post #17

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