VACUME

I have a 1970 vette small block. replaced and rebuild headlights and windshield wiper door and every thing else. when i turn the car on the wiper door and headlights go up then down avery  and i mean every thing new whats up thanks  

if the vacuum assisted devices open and close slowly...  you might have a vacuum leak..  perhaps the vacuum reservoir hooked up  backwards.. so its not storing vacuum when the engine is not running..

do you have the factory manual .. or just the vacuum accessories section to trouble shoot the system???




so.. do you have the info at your place.. and how about a vacuum gauge with a tee fitting on the end of  a length.. or a brake bleeder hand vacuum pump to test the sections and devices..  

E is a filter.. but its more than likely a carbon filter to catch and absorb any fuel vapors that boil up from the intake manifold to protect the system from gasoline vapors..

D is a metal check valve..   single sided is the manifold side..   double sided is the system side...

C is the vacuum reservoir..    if the CHECK Valve at location C does NOT hold vacuum in the reservoir C.. every you start and stop the engine.. the vacuum operated items will probably move..

since i don't have a C3 to examine first hand...  as i mostly do a few C4 models..  a three pronged check valve is currently available in many parts stores..

this is a dorman 47150 vacuum check valve..  usually found out in the isles of the parts stores in the HELP section on a HELP card..




this is a 47149 vacuum check valve.. few stores are going to have this.. but they are available..



the hose sizes are probably wrong for what you are replacing.. as i recall the metal check valve used by gm had 1/4" fittings on both side.. but i could be wrong..     i am not telling you to install the WRONG part on your corvette.. i am trying to help solve your issue until you can get the proper part..  test your check valve..