Vacuum Questions on an F134

Where can I find information on vacuum related issues that affect the F-134? I am using a Carter 938 SD carb, have an original fuel pump and get a reading of 5 on my vacuum gauge. I installed extra spacers on the fuel pump to stop the backfire and lost the wipers. I have now taken the spacers out and still have no wipers...??? I was told to reuse the old slow idle jet screw and it runs much better but the vacuum or lack thereof has me concerned. It is keeping the engine from running smoothly but it is running better than it ever has.... How often is the valve on the breather tube replaced? I know it all starts with properly adjusted valves but am I missing something here?

 

If you are getting 5 inches vacuum at the manifold, at idle, I don't see how the engine could be running at all. It ought to be 15" or more. 20" would be good. Are you reading "inches of mercury" on your scale, or some other unit?

Need more info on how you are getting this reading.

 

I am reading this as 5 inches vacuum at the fuel pump\vacuum, correct. The diaphragm is likely leaking/broken causing low vacuum.

 

That's possible, if he is measuring just the pump vacuum. But his question seemed to also be about engine performance.

 

Which end of the fitting attached to the intake manifold am I to use for testing vacuum? The one that goes to the heater controls or to the side valve cover?

 

Don't use ANY fitting... take vacuum directly from the port in the head, just under the carb on the passenger side. You don't want any other accessory draining the vacuum while you test it.

In this picture it is the brass nut and tube at center, above the distributor.
http://www.thecj2apage.com/forums/uploads/3566/carb.jpg