Pwr Brakes Vacuum question, Challenger 440 mild cam....

The guy working on my car saying the brakes are hard to push....checked the vacuum and he comes up with 10psi?? says should be 16psi???

Car has mild cam and open headers right now....would the cam make a difference? would not having exhaust make a diff?

Any other ideas would be great.....

Thanks.

Did he really say PSI? It's measured in Hg inches of vacuum. If he says PSI, find a new mechanic.

With the right tune up, you will have enough vacuum for brakes.
Some thing is not connected properly it sounds to me?

Got a picture of the engine compartment?

Agree on the tune up A bigger cam normally needs more ignition advance. Up to 20 degrees initial is common. If you post cam specs it would help.

With power brakes 16+" Hg is ideal but they work pretty well down to 13" at idle.

I bet working on the tune will help a lot.

Even at 10 inches of vacuum, your booster will provide some assist.

I had a original booster go bad, it leaked vacuum into the motor causing it to have arratic idle and small back fires on decell.

So instead of using a another original I had, I ordered one from Rock Auto. Put it in and it did not have as much assist it seemed. Maybe my vacuum was to low for it? But as about 15 months went by it lost all vacuum assist, the car had a real hard petal at the end.

Then I pulled it off and installed a original 73 booster I had since like 1982. It works great again and my brakes are back to full power assist, and with only about 10-12 inches some times.

The booster from Rock was wacked from day one, I didn't take it off the car until like 15 months later and didn't even call them and complain, I waited too long.

Quote:

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With the right tune up, you will have enough vacuum for brakes.
Some thing is not connected properly it sounds to me?

Got a picture of the engine compartment?

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I can probably have him take a few at different angles....Car is in PA.