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mbalbritton 08-08-2002 11:34 AM

What is the part between Vac.Advance and Vac Sourc
A buddy was telling about a part that is run between the vacuum Advance, Vacuum port on manifold and vac port on Carb. He and I both have a momentary sluggish point from dead stop. But we always figured it to be the crappy gearing of our T-150's. Then recently he found out about this part described above. Anyone know what I'm talking about here, and if it might lead to our symptoms? this is on our 304's.


kerryp 08-08-2002 12:59 PM

Re: What is the part between Vac.Advance and Vac Sourc
give me a better description of what this part is suppose to do. I'm having a hard time understanding your post. Are you saying that this part mounts inline between the Vacuum advance port on the manifold and the vacuum port on the carb and is suppose to do something to help out your sluggishness?


mbalbritton 08-08-2002 01:49 PM

Re: What is the part between Vac.Advance and Vac Sourc
From what I understand, the Vacuum Adv. coming off the Distributor runs to this part, and then there are two more lines running out of it, one to a vaccum port on the cab and one to the intake manifold. he gave it some long [censored] name that had like 4 words to it. I just called him, he said it's called a Non-Linear vacuum Regulator Valve

the problem were having that we think this has to do with is:

from Dead stop, there is an initial and momentary sluggishness, almost to the point of stalling. to avoid it, you have to pop the throttle and up the RPMs then start letting out the clutch. But if you just give a touch of gas and start letting out the clutch the engine will start to stall. I've gotten so use to it I get around it with out even thinking, but it becomes a PIA when you're trying to ease up a rock or someting.

Anyone familiar with this part, and might it be the missing link under my hood. He said it's about 1.5" in dia. and 1.5" thick withthree ports on it, each labeled for Dist, Carb and Vac Adv.


Caver Dave 08-08-2002 02:13 PM

Re: What is the part between Vac.Advance and Vac Sourc
Sounds like a themo-vacuum switch to me. It screws into the intake (seems like in front of the carb) and "adjusts"(?) the vacuum depending on the temp of the engine. Not very common on our vintage of Jeeps, but plentiful on later smog blocks.

ozarkjeep 08-08-2002 07:59 PM

Re: What is the part between Vac.Advance and Vac Sourc
Ive seen some AMC360s with a thermal controled vac advance, where at differnt temps the vac source is changed.

on My own 360, I elimnated that stuff, and simply use whats called a vacum delay valve.

its like red/green, or red/white ( I beleive these are differnt values available) its about teh size of a 50cent piece, and its plasttic, and about 1/2 inch thick with a nipple on each side, it basically stops all vac passing, until a certain level is reached then opens all at once.

I had to order one when a dip****z mechanic ripped it off years ago and threw it away, then never could get the hesitation out of the engine.

it was about $14, but took about an hour going thru catalogs with a decent parts guy at a Jeep dealer.

trying to help!

**DONOTDELETE** 08-08-2002 09:16 PM

Re: What is the part between Vac.Advance and Vac Sourc
The part you are describing is some type of vac. delay valve. I am not familiar with that one. Ford used them to delay the vac. to the vac. advance and or hold the vac. on to the advance and also the EGR systems.. The color of the valve and the number of ports tells the amount of delay or bleed down time of the particular valve. I would suggest you try and get a vac. diaghram for your rig and see if it shows the valve and gives the specs. for it. Ford had a list of the valves and the time delays in the shop manuals. Maybe jeep did also. I have never seen one make as severe a driveability problem as you describe.

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