I have a '71 chevelle with power brakes. Front disc and rear drums. I have replaced the front calipers, pads, hoses, master cylinder and high performance fulid, you know like that high performance helps. Nothing helps! I have changed the rear pads too. nothing. I have recently put a highly strong 350 in the car with a good cam, and my engine shop told me that a vaccum can from summit would help with the vaccum for the brakes, I can't tell a difference. I can stand on the pedal with both feet and the car wont lock up, but it doesn't stop either. What should I do? tongue.gif

Have you checked the diverter valve under the master cylinder, possibly not getting sufficient pressure to front disc?

Do you have any vacuum? How much before the booster? How much after the booster? You may have a leak. I took off my vacuum brakes and used a Hydraboost setup. It works great on my Jeep. Runs off the power steering pump. Best of luck. Dennymac

You definatly have a vacuum supply problem, get a vacuum guage and hook it up to the manifold somewhere and see what you have.

Definitely sounds like a vacuum problem... can you measure the vacuum, or at least tell us what cam is in there?

Time to switch to manual brakes and get rid of the problems!

Bill C.

I never thought of checking the vacuum. I'll do that today. The cam I have is Melling performance 232 int.,232 exh. I put a 2500 stall to keep the car idling right. It’s doing good now. I'm going to by a vacuum gauge right now, let all of you know how much vacuum I have. graemlins/clonk.gif

I have power drum brakes and ran into vacumme probs due to my cam.

I was lucky enough to get away with using a vac can (reserve)... might be all you need too.

-Greg