Power brake system won't lock brakes
I installed dual master cylinder and booster into my 47 stake-bed with 351W engine. I used a kit made to replace the original under the floor. (kit came from MBM brakes and is designed for a 1/2 ton) Thus,had to modify the 3-bolt pattern somewhat by elongating one of the holes plus cut and weld original push rod to the new push rod. Also, installed four 10 lb residual valves as well as a metering block to prevent front end from diving (couldn't really tell any difference with or without block but installed since I had it.) The pedal pressure is lighter now and is much like any vehicle with power brakes and it slows the truck very well. (I am still using the stock drum brakes.) The big problem I am having is when I push the brake pedal as hard as possible to "lock up the brakes" for a panic stop it doesn't happen. The truck will slow down fast like I have an anti-lock system but just won't lock em up. Still trying to figure out why. My mechanic said the wheel cylinders, pads, drums, etc. are good. Wondering if there can be a problem with the size of wheel cylinders as related to size of M/C, etc.? Any ideas and suggestions will be appreciated.