OK new to ECC,new to Chevy. ive read alot of the post on here that deal with soft pedal and have been able to narrow my problem down to the MC. but in trying to troubleshoot my brake problem i ran across something i find odd. when i removed the vacumm line from the booster i expected the idle to drop and become eratic but instead it climbed to 2000 rpm ???? i backed my idle screw out til i was once again at 800 rpm and it still idled as smooth as if it was capped(at least as smooth as a 650 lift cam would)ive not tested to find out the actual vacumm but it feels like plenty and the pedal does what it should (gets hard with vac disconnected)so im sure the booster is ok its the idle going up that has me baffled is it normal? I dont want to sound stupid but this is the first bracket car ive had with power brakes how hard would it be to convert it to manual?thanks in advance.~Ron :dontknow::dontknow:

First of all welcome to ECC .
Now for the brakes, a soft pedal usually means air in the system,with a bad master cylinder you will see fluid leaking in on the floor or leaving a trail of fluid down the booster,if the M/C is bypassing internally the pedal will hit somewhat normally when depressed then while holding your foot on the brake the pedal will continue on down to the floor.
Check the inside of the tire sidewalls for leaking brake fluid,also check the flexable brake lines for weeping(this is a good place to get air in the system).If you don't find anything amiss in those areas try bleeding the brake system starting with right rear,left rear,right front and then the left front .There is more that can be tried but I'll stop and let others chip in their ideas. Good luck and again welcome!

welcome B...:texas:
sounds like the carb is fat/rich?? if its a holley?? could be the power valve is opening with the lower vaccum,,
making up for the vac. leak..most carbs have an enrichment curcuit and with the cam (lower vac.),,the throttle blades are usually open a little farther at idle ..
it could be normal...its too early..

Thank you guys for such quick replies im certain it is internal seepage in the MC as it almost feels normal then goes to floor and im not finding anything leaking. It is the idle going up when i unhook the vacuum line that has me baffled. im not a mechanic but ive been around awhile my experience has always been for the motor to stumble and about die.~Ron

ok i spoke with my engine builder(A man i have absolute trust in)idle going up is normal as this is a Race motor not a street motor.Now i just want to say thanx again for your quick responses:You_Rock::beer:

With vacuum leaks there is no set reaction for the engine.I have seen car engines die with a small vacuum leak and another of the same make and model,year and engine race with the same leak it just depends on a given set of conditions as to the reaction it will have.The circumstances of a malfunction is best analyzed without a vacuum leak as you have been working towards.Most problems are solved by elimination of possibilties until the condition is remedied.

wadd he say?? too many of them big words GC..:poke:

yep sounds like a bad mc,,

thats a good lookin elky B,, whatcha got in it??:texas:

Thank again fellas JJ its a 1969 327 with a set of 1966 double hump heads stock bore and basic stock bottom end and a Lunati 656 lift 294/294 dur hyd cam Th350 with a B&M shift kit 12bolt rear with 411's and full spool & moser axles. Batteries are relocated to the bed as well as a 10 gal fuel cell. No interior other then a race seat steering wheel and shifter autometer gauges. we are in the mid 12s @ 105mph in the 1/4 i could talk about it all day and my wife says i will til someone tells me to shut up lol. Tailgate is PINK and has the phrases "save mans real best friends" and "save the tata's" emblazened on it with the breast cancer awareness symbol in the middle.