Engine vacuum & power brakes

[cuda67]

I need some help, please. I have a 318 in my car, within the pass year or so I have done a few things some of which I am pleased and with others?? I need help with my power brakes. I am not developing enough vacuum to properly operate them. According to my vacuum gauge my engine only makes at most 11 inches. and I haven't a clue as to why. I have been told that I need 16-17 inches of vacuum to operate power brakes. I do not have a big cam and I don't have any extra stuff. My cam is a Comp cam 280/480 in my book that is mild. I added an auxillary canister to hold vacuum but that didn't help. Does anyone have any ideas? I would like not to have to use a vacuum pump. Any clues or suggestions? Don't mis-understand I have brakes it is just not power brakes.

 

[ramcharger]

The Comp 280H has 230 degrees of duration at .050 lift. In a 318, is pretty big cam and and your vacuum reading are actually pretty good for that size cam in that engine.

Switch to manual brakes if you don't want to run a vacuum pump. You will never get 15"+ with that cam in that engine.

 

[cuda67]

The Comp 280H has 230 degrees of duration at .050 lift. In a 318, is pretty big cam and and your vacuum reading are actually pretty good for that size cam in that engine.

Switch to manual brakes if you don't want to run a vacuum pump. You will never get 15"+ with that cam in that engine.

Ram, I know you are right about the cam. If you heard it there is no doubt, in my opinion. It is just that my sons are Ford guys and it sounds like a mild cam to them. They are hard core Ford. They say my brakes are fine and that I am too picky.
By the way, if I would decide I want the whole effect of power brakes, how dependable would a pump be and where would be the best place to mount it? I been told the trunk? I also have been told under the hood. I just don't know. If I use a pump is it in conjunction with the engine vacuum and the canister or do I remove all that and the pump is a stand alone system?

 

[MopaR&D]

Ooh, that must hurt having Ford guys for sons! (j/k) That is a pretty big cam for a STREET engine; obviously your sons are thinking in more "strip" terms. I'd say swap to a Comp XE262 or 268; you'd probably gain more torque across the whole RPM band and your vacuum would definitely go up. Mopar engines require different thinking when doing modifications because of their different engineering (most of us here will say "superior"), and when done properly will walk all over GM and Ford engines of similar size/application.

 

[dusterdon]

Ditch the booster. The only thing you'll need is a manual brake pushrod. I have manual brakes on my duster and like the feel of them better than power.

 

[MopaR&D]

Ditch the booster. The only thing you'll need is a manual brake pushrod. I have manual brakes on my duster and like the feel of them better than power.

That's a good option too. I also have manual front disk brakes on my Duster and I can lock them up no problem. The pedal feel is also more "progressive" and is less sensitive.