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Author Topic: Vacuum Advance or No Vacuum Advance  (Read 3279 times)

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Offline Tumbleweed

Vacuum Advance or No Vacuum Advance
« on: October 14, 2014, 12:14:32 PM »
Are there any advantages to using a distributor with vacuum advance vs. no vacuum advance on an L134? I had this distributor left over from my last rebuild on my F Head. If I have to rebuild my old distributor (non vacuum advance) I might just opt for an electronic version. I did this on the F head and have had no problems.

George
49 CJ3A - "Smokey"
53 Willys Wagon - "Wylie"

Online Bob W

Re: Vacuum Advance or No Vacuum Advance
« Reply #1 on: October 14, 2014, 09:14:35 PM »
A vacuum advance increases fuel economy. How much can you hope for in a CJ-3A?  ;D
Bob W

Offline Tumbleweed

Re: Vacuum Advance or No Vacuum Advance
« Reply #2 on: October 15, 2014, 09:25:57 AM »
Your correct Bob - that about that last thing I think of! Since this is a new rebuilt distributor I think I will use it and spend the money on other parts.

George
49 CJ3A - "Smokey"
53 Willys Wagon - "Wylie"

Offline Tumbleweed

Re: Vacuum Advance or No Vacuum Advance
« Reply #3 on: November 25, 2014, 03:53:41 PM »
Does anyone out there have a setup like the one in my picture on their CJ3A? On my wagon the vacuum came off the carburator I think. I guess another option would be the intake manifold? A friend of mine has an intake with 2 fittings at the top - 1 for the duel pump carb to operate the wipers.

George
49 CJ3A - "Smokey"
53 Willys Wagon - "Wylie"

Online Bob W

Re: Vacuum Advance or No Vacuum Advance
« Reply #4 on: November 25, 2014, 04:23:51 PM »
Typically a vacuum advance uses ported vacuum so there is no vacuum present at idle. When the throttle is opened it uncovers the "port" in the carburetor and vacuum is supplied to the distributor advance. A manifold vacuum fitting will supply vacuum at idle.
Bob W

Offline Jesse

Re: Vacuum Advance or No Vacuum Advance
« Reply #5 on: November 25, 2014, 09:01:49 PM »
I have a vacuum advance setup and now that I think about it I'm pretty sure it is plumbed into the intake. I should check on that ported vacuum on the carb and make sure it is correct.

-Jesse
Its a jeep thing, but you would understand if you have ever lost your wallet.

Offline Tumbleweed

Re: Vacuum Advance or No Vacuum Advance
« Reply #6 on: November 26, 2014, 12:15:10 PM »
Sooooo, do you necessarily want vacuum at idle? I don't know if my WO carburator has a place to put a vacuum hose (line) till I get it back from scoutpilot. Again that was how it was set-up on my F head.

George
49 CJ3A - "Smokey"
53 Willys Wagon - "Wylie"

Offline Carls_jeep

Re: Vacuum Advance or No Vacuum Advance
« Reply #7 on: November 28, 2014, 02:25:16 PM »
The vacuum advance holds the advance at a high point at idle and at cruse speed, steady throttle. When you step on the throttle the vacuum drops and the distributor gets retarded to the preset advance setting.

High advance under a load will produce engine knock but at steady throttle the engine can use extra advance for fuel economy.

When setting the timing with a vacuum dist. you remove the vacuum line and set the advance per engine manual specs. then reattach the vacuum line.
« Last Edit: November 28, 2014, 02:26:00 PM by Carlsjeep »