I'm starting in on my hydroboost install in the next couple of weeks and am planning on installing a proportioning valve at the same time. I've got discs from a '78 in the front and drums in the rear. I have a stock prop valve from a '76, but realized that I'd probably have to swap out the hard line running from the valve to the rear hose. It may be cheaper and easier to install an adjustable valve between the MC and the H-block. How well do the adjustable valves work in comparison? Are the mainly for fine control, or can they handle larger adjustments if needed?

Just installed one on my sons, XJ. He cannibalized a 72 Bronco for the front D44 and the rear 9" for the Heep. Removed the current set up and removed the ABS which required the adjustable valve. Very good for that use and really helped him out as far as adjust-ability, he did a disc conversion on it also with still the stock shoes in the rear. He had no Prop valve with the ABS setup.

I hope that helps.

I'm not sure what it would do without the stock prop valve. Many H-boost trucks end up with too much rear bias, mine did (Mustang h-boost & m/c)-stock h-block & prop valve. I talked to BC Broncos at length about this, they said do 1 of 2 things. Add a prop valve to the rear brake line & "turn them down". Or install the large piston T-bird calipers up front. I did the T-bird calipers and they work great.