New Brake Booster Problem...HELP

So I just replaced my old tired Treadle Vac booster on my '53 Bel Air with a new 7" Double Diaphragm booster with proportioning valve. Installed the whole setup and re-ran the brake lines. Bled all four lines from the back forward, and seem to have gotten all the air out of the system. The problem is that when I go to apply the brakes now, there is little response with pressure until a point, then all of a sudden the brakes really grab and engage. So it's like there is not any response then an immediate over-response. It also appears that the back brakes are grabbing the hardest, and if I hit it too hard they lock up really easy. I should say I am running all four drum brakes, and told the guy I ordered it from I had a drum setup (since there is a spring proportioning valve next to the rear master cylinder outlet). My question is:

1. Why are the brakes not responding then all of a sudden responding? There isn't a gradual increase in breaking force.

2. Why are the rear brakes engaging the hardest when there is a proportioning spring in the prop block. On this spring there is a nut. Is this proportioning spring adjustable or is it set?

I have linked the product I purchased below if it helps. Thanks in advance guys.


http://www.belairbrakeparts.com/proddetail.asp?prod=PB-377974

 

Im working on doing this to my 52 but stalled as of right now due to buying a house. Id say you should have tried it without the valve 1st. You might not need it with drums all the way around. Since you have it installed already, you might not have it adjusted properly. Sounds like your getting too much pressure to the rear.

 

the pic looks like a set up for a disk/drum car. also,,do you have the lines plumbed properly??

 

You shouldn't have a proportioning valve with 4 wheel drums. The master you show says it comes with one and that may be what they shipped you. If that's the case, you also may have the lines reversed, which would make the rear brakes to see more pressure, causing them to lock up. You can fix it by either replacing the proportioning valve? with a drum brake distribution block or just reroute the lines directly to the master. You should also install some 10 lbs residual valves as well, since your master may not have any.

 

I guess you guys are faster at typing than me.