i have a 1985 Trans Am with a 350 and a 4bl carburetor.i just bought the car a couple of months ago and the first thing i did was bleed the brakes. they have been doing fine for the last several weeks but in the last two days when ever i come to a complete stop i have no power brakes. when im driving or braking for a stop i have power brakes and they are fine. but after the stop and im rolling again and i have to brake there are no power brakes! its kinda scary. also its never had power brakes when its in reverse since ive owned it. i think its because of a vacuum problem, but if it is how do i fix it? any help, advice, or suggestions would be great, thanks in advance. Btw its a ws6 and has four wheel disc brakes if that makes any difference.

 

I would start with a vacuum gauge and see what you have at idle. If its real low, you have possibly a large intake/vacuum leak, or maybe a cam timing problem. But if that were the case the car would run like hell. Check the hose from the back of the carb to the booster, see if it's kinked. My friend's 85 Camaro had the hard line almost twisted into a pretzel and restricting vacuum to the booster. If all that is good you may want to check out the booster, if may be leaking internally.

 

A very simple test is turn the car off, wait a while (couple hours or more) and then go pull the plastic vacuum fitting out of the booster (it has the hose attached to it, it goes into a rubber grommet in the booster).

It should still have vacuum there (you'll hear it suck in a bunch of air). If not, there's definitely something wrong. The plastic fitting has a check valve and is like $1. But it won't really cause the kind of problems you're having. An internal leak in the booster however can cause those kinds of problems and that is what I'd suspect if you don't have vacuum when you check it after a few hours (Most cars will hold vacuum in the booster for days).