Just got my 9204 booster back from Jerry M being rebuilt and installed. Drove it around the block and now the brakes are staying on. Checked the adjustment rod and there is some play in the pedal so it not jammed against it. I swapped the check valve on the booster and when I pulled it out there was vaccuum present. No help. The system worked fine before the replace. Any suggestions?

Something is preventing the master cyl from returning fully.
It could be brake pedal adjustment, or the pushrod to master cyl length. If you loosen the master cyl to booster the brakes should release. I had to shorten slightly the booster to MC pushrod on my wife's car. If the wrong pushrod or master cyl is used it can be off as much as 1.350!

I'd first make sure the pedal is not pushing on the pushrod, then check into the master cyl depth and rod length there.
Look on my web page here: http://www.pozziracing.com/brakes.htm#Booster
David

Thanks Dave, I did check your site and it looks like I have the correct parts. I contacted Jerry and he said to try the shorter booster rod. The pedal free play looks ok. It's like you say, something is not letting the MC to release. I have the deeper MC piston and the longer rod.

Are the lights staying on or does it seem like the brakes are applied?

It's the rod length. I installed the shorter rod and it releases fine but the pedal has to be depressed too far to engaged the brakes. Do the rods only come in the 2 sizes? Is it pretty common to have to cut them down a little?

It was on a second gen but the same sort of thing.
I installed a reproduction Delco Moraine booster and used a 15/16" master cyl from Baer Brakes. When I installed the master cyl, I could feel extra resistance holding it up there. I pulled the rod and machined it a little shorter. I made sure the pedal rod was not being held in first. I only removed aprox 1/8" but I'm glad I knew to watch out for it.

I'm glad I knew to watch out for it.Experience is the best teacher.