Vacuum Dilemma

[VAJeepGeek]

Dang Vacuums!!! I just finished the rebuild and now have to finish with the vacuum hoses for the engine. The PO really messed things up, most of the hoses are just plugged up.. :(
Now to the questions:
1) Are the vacuum diagrams the same for an 85 360 and an 80 (or so) 304? :confused:
2) I know the 360 diagram I have calls for a HDC CTO Between the Distributor and the Carb, but there is none??? Errr...? :mad:
3) Right now the vacuum hose to the Power Valve(i think.. :confused: ) on the front of the carb is just plugged off (Carb was rebuild 5 days ago...). Would this be the reason why it still stumbles on hard acceleration?

Thanks for all the help already everyone, This place is truly a lifesavor for us Under Educated with Motors... :D

[VAJeepGeek]

btt

[joe]

Originally posted by VAJeepGeek:
1) Are the vacuum diagrams the same for an 85 360 and an 80 (or so) 304? They're not even remotely close. The 80 CJ diagrams differ between 49 state w/AT, CA w/AT, 49 w/MT, Ca w/MT, hilly terrain blah blah. If you have the 85 diagram for the FSJ 360 I would go by that if you ever plan to pass VA smog checks.
The HDC CTO is just used on the Heavy Duty Cooling systems. If you don't have that you won't have that extra CTO either.

[VAJeepGeek]

Thanks Joe :D ,
Just wondering, where does the vacuum hose from the power valve normally go?

[joe]

I don't remember if it's the early or late carbs(don't have one here to look at) but one gets vacuum(manifold) from an external vac source and the other gets it internally from the carb. If yours has a vac nipple on the housing for the PV it needs to be hooked to manifold vac.

[khurst]

Fred,
I feel your pain just finally got my 401 in an 89 "tubed" up correctly--got to tell you EGR is key to elliminate pingging!ha! Anyway the power valve should be connected to the vacume resevoir according to my 89 Jeep service manual. That power valve is designed to kick-in with a loss of vacume, so right now with it plugged off you have enabled the power valve all the time and it will cause you to run richer and could very well be the cause of the stumbling. I would also check your vacume advance tubing-remember the cto supplies manifold vacume to the distributer when below 165deg via a vacume delay valve(4 sec.), after 165 it supplies "timed" vacume(vacume only present when throttle is above idle) if this is reversed you may be retarding the timing on hard acceleration b/c manifold vacume drops on acceleration and timed vacume increses on acceleration. CTO connections are as follows-bottom port- timed vac. supply
middle port- to distributor
top port- manifold vacume(via delay valve)
p.S. remember you have a non-liniar valve in-btwn these connections
Hope this helps some, Kirk

[Don S]

Originally posted by -joe:
I don't remember if it's the early or late carbs(don't have one here to look at) but one gets vacuum(manifold) from an external vac source and the other gets it internally from the carb. If yours has a vac nipple on the housing for the PV it needs to be hooked to manifold vac...
-joe:...
Just for a reference point my ’81 360 Wagoneer was delivered in Wyoming with a MC-2150 with the Aneroid Altitude Compensator and an internal vacuum feed to the power valve
… I liked it so much I thought about swaping onto my ’76 401…
… Per the 1981 TSM all (five) MC-2150s are internal vacuum feed to the power valve. There is a surprizing amount of differences in the five MC-2150s and you have to set them by 'tag numbers'
:mad:
The venturis are even a different size... :eek:

Good Luck and CUL ;) … ds..
- - - - - - - - - - - - - - - - - - - - - -
1976 Wagoneer 406 MC4300 TH400 QT TruTrac 2" lift 31x10.50s duel Optimas
It’s taken us over 261 Colorado Mountain Passes since 1985-
link> 2003 OURAY FSJ Invasion Info and High Altitude Tips (http://groups.msn.com/ATexasOklahomaJeepClub/ouraycotopic.msnw)
link> Acronym and Abbreviations for 4X4 Gearheads (http://groups.msn.com/NISSAN4X4TRAILS/acronymlist.msnw)

[mechanic58]

You don't need a diagram....it's simple. You have two kinds of vacuum...primary and secondary. Primary is a vacuum source that originates BELOW the throttle plate and Secondary is from ABOVE. Your power valve needs to be hooked up to secondary just like your distributor advance. Most everything else goes to primary. Your EGR valve should be hooked up to a temp switch that is hooked up to primary. Here's how you tell the difference at the carb (assuming your engine runs well and you don't have the throttle plate opened in order for it to idle) Vacuum ports on the carb that have vacuum on them at idle are primary...ports that only have vacuuum during opened throttle are secondary. I hope this helps.

[VAJeepGeek]

Thanks guys... I'm going to try to check out where all of the vacuum lines run tomorrow. I know the vacuum is really messed up, I don't even have a charcol canister. All of those lines are just plugged up.. ? :(
You guys gave me some real good info here, thanks alot... :D Really!!! :D

[VAJeepGeek]

Geezzz.. I really hate vacuums now!!!! :mad:

OK, these are the diagrams that I've found..
http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/Vacuum_Diagram_V8.jpg

So what your telling me is that I need to hook up the Power Valve (it is external vacuum required) to the Manifold Vacuum line off Port #1 of the CTO (Fig. 36)??? :confused:

And now... What the heck is the delay valve and where is it needed???? :confused: :confused:

I beg you ohhh FSJ Gods to bless me with your wisdom.. :D :D Please... smile.gif

[VAJeepGeek]

btt

[VAJeepGeek]

btt

[reddog]

Any manifold vacuum will do for the power valve. The vacuum line to port#1 on the cto is fine as long as you put the T before the check valve shown in that line.

The delay valve slows the changing vacuum down to delay or "smooth" the effect of vacuum on whatever is sensing the vacuum. They are rated by color as to how long the delay effect takes.

There are a number of them on an 80s FSJ. As I recall there are none in the power valve vacuum feed.

Kerry