I am running 4 wheel discs on my IH truck 3/4 ton axles. Four wheel disc m/c from a 69ish cam plumbed straight to 3/4 ton chevy calipers and rotors at all corners.

With the new M/C and direct plumbing it stops better but not like it should. The pedal fades and feels like there is no assist.

I have a 268H Comp cam and wonder if it pulls enough vaccum at idle...I checked the hose and it seems to suck quite a bit of vaccum.

I took out the can of carb cleaner to search for vaccum leaks. I sprayed around the carb and such and it was fine.

I sprayed the top rear of the mc where it bolts to the BOOSTER and the idle tached up.

Since it seems like I have no power assist to speak of and the idle rises I suppose the diaphram in the booster is busted. Any thoughts? The brake pedal will pulse slightly when you put your foot on it.

Anybody else think the booster is bad or had similar problems???

Thanks.

I went through this same thing with my camaro, changed the master cylinder, it helped, but pedal still didn't feel right.. went searching for vacuum leaks with a can of starting fluid and found the idle jumped up when booster was sprayed,"under dash" changed booster,brakes fixed