More Mc2100 confusion

[Petescj]

Ok lets just start with the Salvage CJ7 Mc2100 works fine. I ran the Jeep for a year after I installed it with no problems. I decided to do the same with the Scrambler. After messing around with a hand me carb down I bought a rebuilt one from Ebay. It worked well in the garage so I thought.

I figured it was kinda cranky due to the cold weather and the fact I had no choke hooked up. I had to keep it reved up awhile till it stayed running. It was warm enough now in Aug ( ) and I had the same result. Then even when it would idle once I let off the clutch it wouldnt move without stalling. I had to stage it like a drag car more a less.

I decided to use the Salvage Cj-7s carb and swapped them out. The Salvage carb gave me the exact same results on the Scrambler.

 

[Petescj]

There is one difference to the carbs I used. The one from the Salvage CJ7 has a port on the backside of it. I had to use this "valve?" with it or it wouldnt run. It is in between the Pcv valve and the rear port of the carb.

 

[Petescj]

When I hooked everything up in the CJ7 configuration I got positive results. That leaves me in a bit of trouble. The carb I have for the Scrambler dosent have that rear port. I used a port in the manifold directly under the carb like this. I have the fitting capped in this pic

 

[Petescj]

I cant understand why the vaccum maybe 1in. under the carb would be different. Its coming from the same place. Am I just a knuckle dragging Neanderthal in my thought process , or is there big magic in that valve? Niether Cj will run without it.

 

[Cheepjeep85]

when you say neither will run without it does that mean only with the scramblers carb, or either carb on either jeep? and is that valve connected to anything else?

 

[phinleft]

Mine had a similar issue, and it turned out being an air leak that I found spraying carb cleaner around the intake. Had to replace the intake gasket.

 

[elwood blues]

Is there a chance you could take a picture of the 2 carbs side by side Pete? This one's got me scratching my head too

 

[Petescj]

The 2 carbs are the same except 1 lacks the vacuum port at the rear. Both carbs act the same without that valve. They'll crank over and run , but wont idle , it just dies immediately. The rpms have to be really high and feather the clutch to get it to move or it stalls.

The valve is connected to the pcv valve and the vaccum port at the back of the carb. I'll take some more pics this afternoon.

 

[Cheepjeep85]

that is a little weird, first thing that comes to mind though pete is maybe that little valve is limiting the amount of vacuum that is being pulled on the pcv, and the carb wont stay running without being reset to run at full vacuum through the pcv. idk maybe im talking out of my <-BAD WORD->, but its a guess.

 

[Petescj]

I just dunno. Im gonna see if theres a diagram that may name what that valve is. I dont even know what to Google. I have one project going on tonite that I'll share later on. May not get to it till tomorrow.

If I get a barb to step the vaccum line down to the correct size of the nipple under the carb and all is well I'll be happy. It'll be easier to understand with pics. Basically I have a larger line coming from the valve that has to convert to the smaller one on the manifold.

 

[Cheepjeep85]

is the pcv pulling vacuum with that valve hooked up (alot or a little), if so is there any increase in vac when you remove it?

 

[Old Dog]

I'm thinking cheap might me on to something here.

 

[Petescj]

is the pcv pulling vacuum with that valve hooked up (alot or a little), if so is there any increase in vac when you remove it?

I'm thinking cheap might me on to something here.

I spent a little time hittin the brake bleeders with Pb blaster. That was it. I'll check , as best I can Cheeps theory. Maybe I can grab a vaccum gauge somewhere. If not I'll try it by "feel". I looked on the grill shell for some kinda advice. This was still there:



Dont put your hand in the moving fan / or open the gusher when hot.

 

[Petescj]

Well one thing I have determined now. I can use either carb as long as I use the magic valve. I blocked off the port on the rear of the carb that had one. I then ran the line down to the manifold underneath like I showed earlier. I changed out the "nipple" so it would be the same size as the Pcv valve.

The pic shows what I had in on the right. I switched to the one in the middle to keep things "uniform". Without the valve it will run as long as Im steady on the gas , like you were warming up a carb in the winter. With the valve/regulator it behaves much better.

 

[Cheepjeep85]

thats weird man, you say you only have to use this special valve on the CJ8 , or both with either carb.

 

[elwood blues]

Yeah Pete, that's really weird. I would like to see a pic of where that hose barb you bought goes.

 

[Petescj]

Have to use the valve on either Jeep with either carb. The barb is located directly below the carb plumbed in the manifold. Im going to see a friend in the hospital this morning. I'll post pics when I get back.

 

[Cheepjeep85]

I'm out of ideas on this one man, it would be nice if we could identify what that valve is. On a side note I searched every emissions diagram I could find and couldn't figure out what it is. Makes me wonder if its a fomoco part.

Droooiiddd 2

 

[Petescj]

Well it was there prior to the swap. Im just glad that I determined I can use either carb. I'll just keep it in on both Cjs and that'll be it.

 

[yellow85cj]

For some good 2100 info, try going here to a list of Coas' (forum member a wile ago on another forum) PDF's. THere are several on the 2100 and one (don't know which one) that explained the differences of 2100's and what ports on the base that needed to be blocked on some models.

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