Brake distribution block

[ponyexpress]

Is the stock brake distribution block used in conjunction with a proportioning valve when changing to front disc brakes? Or should I eliminate distribution valve and just use proportioning valve. The technical article on disc brakes does not cover this part of the conversion.
Thanks

[ultraranger]

The Bumpside F100s only came with all-wheel drums (power brakes was optional) and the F100s only came with one type of brake valve. This would be a pressure differential valve. All wheel drum brake systems don't use proportioning to the rear drum brake circuit.

Beginning in 1968, optional factory front disc brakes were available on the F250s and F350s. Power brakes were also optional with this. These trucks also used a pressure differential valve (like the drum/drum trucks) along with a stand-alone metering (hold-off) valve plumbed into the circuit going to the front discs. The '68-'72 F250/F350 Bumpsides with factory optional front discs didn't have any proportional valve function to the rear drums either.

Manual front disc brakes became standard equipment on all F100 - F350 trucks beginning in 1973. Power brakes was optional. In 1973, three brake functions were integrated into one valve body assembly. These functions were: Metering (hold-off) to the front discs, Pressure Differential sensing between the front and rear brake circuits and Proportioning to the rear drums.

If you are going from front drums to discs, you need an OEM valve from an equivalent series donor truck that contains these 3 features or, you could install an aftermarket manually adjustable valve setup. If the choice is to go with the latter, be aware it will NOT have a Metering valve or a Pressure Differential valve inside the valve body assembly.