I have a 68 vette with what the previous owner indicated was a mild cam.  The headlights open, but slow, one at a time.  The wiper door will not open and so I have it locked open.  I was told that the vacuum pressure is being affected by the cam.  Is there some type of add on that will increase the vacuum pressure assuming all the hoses and etc. are not leaking?

I know their is something but I don't know what it is. My guess is it's a combination of a bunch of little leaks here and there and some bad hoses, some weak springs. Unfortunatly there are so many things in this system that get old and worn. I would suggest getting a system guide so you can go through and test everything and find out what's wrong. You'll need a vacuume tester. Got mine at Sears. It takes time but I just went through and followed the guide and fixed all the little leaks. Now mine works fine. 

  Check out this site. It should help you. "T"

http://www.corvette-101.com/vacuum.htm#tools
my7T12010-02-22 13:29:34

Great.  Thanks

I have something from Doc Rebuilds thats called " What, Where and how to troubleshoot The headlamp and wiper door vacuum system". I don't have it on my computer. If I did I would send it to you. I don't think I'm smart enough to scan it. Maybe someone else has this.

I guess I am smart enough. I now have this on my computer. Private Message me and I'll email it to you.

Once you fix the leaks you can add an Air tank with a one way valve to store vacuum.  That way when the engine has some vacuum, it will store it and the one way valve keeps it when the engine vacuum is low.  These are used to compensate for the low vacuum caused by the cam.  JEGS and Summit and others sell them as aftermarket Air tanks just for low vacuum caused by the hot cams.

Really don't think its the cam, if the system is vac tight,  check valve, relays etc are ok it doesn't take long  after start up for the system  to operate correctly, don't forget to check the fresh air inner and outer door lines and valves if you have AC, and heater controll, valves, and lines, they are also part of the system. anips2010-02-26 10:04:01

the additional tank helps and be sure the entire system has only ONE check valve. Does anyone have a schematic for the windshield washer sytem - where the hoses go on a 1969 vette?