The Stovebolt Site Forums The Shop Area Engine Shop Where to hook up Vacuum Line

I have just received my CCP master cylinder and booster. The booster has a 3/8" OD inlet but all the vac. outlets on my 1975 / 250 in line 6 are all 3/16" OD. Should I drill a hole in the intake manifold and tap it for a 3/8" fitting or ? Anyone done this before? Hope I have the required
18 lbs of vac they suggest.

Your nearest auto parts store carries many adapters, T's, Y's, etc. It should be easy to locate a 3/16-to-3/8 brass or plastic adapter.
Don't drill/tap your manifold; besides being irreversible, it's a lot of work and it's also likely to get metal filings into your motor.

A 3/16" line might have real trouble supplying adequate vacuum volume.

You should have a 3/8" port on the center intake runner, between the carburetor and the valve cover. This is where the PCV valve hooks up. You are not really suppose to tie into the PCV line with the brake hose, but it may be your only option other then drill and tapping. You could make up a thick carb spacer with a 3/8 port drill in it, it would be pretty easy to make and install.

Joe

Joe H. What would I make a carb spacer out of. Are they made of an insulating material or would aluminum be ok with a gasket on each side ?

if your carb is getting too warm and boiling gas out after you shut it off, you would want to make a spacer out of an insulating material. If everything works fine and you are just wanting put it in there to add a vacuum port, aluminum is fine.