hard braking

[4rox]

I have a 94 ext cab. Its mods include sas,350,ford 9inch.I've recently replaced both rear wheel cylinders,rear brake shoes,master cylinder.The truck stops okay yet the pedal is as hard as when the engine is not running.The engine is a 350 bored .030 over with a healthy cam.Could the cam be part of my problem?What do I do?

[kyle_22r]

the pedal is hard because the engine is not running.  the booster needs to engine to be running to, well, boost the brakes.

[brainlessfool]

if there is no diff. beteew the eng. running and not running then its the booster, or the vac line to the booster. the big cam will weaken the "boost" at idle but coming up to a stop sign it sould not matter.  chek for vac to the booster and leaks at the booster, I use carb. cleaner with the eng. running.   good luck

[kyle_22r]

ah man, my wisecrack backfired on me i need to get some reading comprehension

[WHITE_TRASH]

Yup a big cam will not draw enough vacuum for you power brakes.  Id suggest a vacuum can from summit they're cheap and they will work well for what you need.

[Marlin]

If your truck has a rear load porportional valve, it may be rusted up. Put the rear end up in the air, push the brake pedal, and check to see the rear brakes are working.

Marlin