Vacuum Wipers

[Vincent]

This is a picture of the doodad that was attached to the intake manifold when I pulled the CJ3A out of the field. There were 3 vacuum lines off this. two went to the in and out fittings on the vacuum section of the fuel pump. The middle thicker one was just hanging.  I would assume this went to the wipers.  Does anyone else have this kind of setup? Does it seem right? How does everyone else's vacuum wipers hookup?

[Rus Curtis]

Vincent,
I'm more familiar with the F-head than with the L-head.  However, I believe the vacuum function is the same.  That inlet port on your manifold is where engine vacuum is created (our F-head vacuum manifold inlet is on the passenger side). 

If the engine ran at a constant speed, I think the vacuum wipers could be connected directly to this inlet and they would work too.  However, engine speed (and therefore vacuum pressure) changes as you drive.  The fuel pump has a vacuum boost on the bottom (one inlet and one outlet) to assist with vacuum as its pumping changes with the rpms.

I remembered a similar issue back in Sept so I went back to that source for pictures (from Derek's CJ3B Page - Joe Caprio's 1951 CJ-3A):


Locating the vacuum port in the intake manifold (just aft of the carb) you can follow the vacuum tube forward where it bends down towards the fuel pump.  Then there's another vacuum tube that runs back up right along side of the first one but this one goes straight back where there is a rubber line attached that exits the side of the tub (this is the hose that goes to the wiper motor - see image below).  So when hooked up correctly, the wiper motor is powered by the vacuum from the intake manifold and is assisted by the vacuum pump on the bottom of the fuel pump.


(another image of Joe's CJ3A):


From this angle you can see that hose travelling up and across the w/s frame to the wiper motor. 

Do you know if the vacuum assist pump works?

[Vincent]

I'm still restoring and installing a rebuilt double action fuel pump. Close to the point of putting this all together. That triple hose connector that was on this intake just looked strange and I am not quite sure how these vacuum wipers hook up. But those pics help. Mine does have driver and passenger side vacuum wipers, if that makes a difference.

[Rus Curtis]

Vincent,
I believe all the fuel and vacuum lines are 1/4" so if you wanted it to look like in the picture sourcing steel lines shouldn't be too hard.

I don't believe two vacuum motors will be much of an issue - it's an option for the 3B so I'm assuming it's an option for the 3A. 

When you get your fuel pump installed, you can turn the engine over (or start it) and hold your finger over each of the ports for the vacuum pump.  One will create a gentle draw and the other should feel like a gentle push.  It may be marked for IN and OUT and if I've got it straight in my head, the push (OUT) should go to the manifold.  The entire system should be pulling or sucking from the wiper motor to the manifold.