New ls swap in streetrod project. Has power brakes with vacuum source pulled from nipple at rear of ls3 intake. With engine off I can pump brakes until pedal becomes gradually very stiff, ie, normal-car has working brakes. Initial start of car checking for leaks and what not, brake pedal feels almost over assisted...like no brakes..don't hear any whistle indicating a vac leak but will begin the search with starting fluid. Is there anything I maybe overlooking? Thanks guys!

 

This sounds like pretty normal power brakes operation. What kind of booster and MC are you using?

Andrew

 

I agree, sounds normal to me too, unless what you really are trying to say is it has a low pedal, meaning it goes too close to the floor. If that's the case, you could still have air in the lines, or one of a number of other issues that can happen. Is the master cylinder under the floor or on the firewall?

 

One way to check the operation of a brake booster is to apply the brakes, hold and start eh engine. The pedal should drop a bit meaning the booster is working fine. If you have to pump up the brakes there is either air in the system or no residual valves (if the M/C is under the floor.)