The Ford Barn - View Single Post - Y Block Normal Vacuum w/mild Perf. Street Cam?

Sid · 01-04-2020, 04:07 PM

There should be a port on the carb. approx 3/8 or a removable plug in the intake for cars that are equipped with power brakes. At a minimum I would expect vacuum to be over 12-14 inches at a full vacuum port. As far as power valve as a rule of thumb Divide your vacuum reading by 2 for a power valve. 12 inches of vacuum probably 5.5 p.v. If your vacuum comes up as an even number like 14 go with 6.5. Always take into account your elevation for jetting especially if you are over about 2500 ft.

01-04-2020, 04:07 PM	#5
Sid Senior Member Join Date: May 2010 Location: Rathdrum Idaho Posts: 737	Re: Y Block Normal Vacuum w/mild Perf. Street Cam? There should be a port on the carb. approx 3/8 or a removable plug in the intake for cars that are equipped with power brakes. At a minimum I would expect vacuum to be over 12-14 inches at a full vacuum port. As far as power valve as a rule of thumb Divide your vacuum reading by 2 for a power valve. 12 inches of vacuum probably 5.5 p.v. If your vacuum comes up as an even number like 14 go with 6.5. Always take into account your elevation for jetting especially if you are over about 2500 ft.