Dual Diaphragm Brake Booster
The camshaft currently in the 433 only ends up with about 10.5-11 inches of vacuum. Just barely enough to run power brakes in my view and results in poor braking performance and feel. Part of improving the car's driveability is a move to a factory 80-81 Trans Am dual diaphragm brake booster as another Covid quarantine project. These are getting very hard to come by but I was able to find it on Rock Auto with a reasonable core charge.
On paper this should increase the pressure available at any given level of vacuum. It's questionable if it is going to be enough but there are some side benefits here. First, the diameter is smaller. The old 11" single diaphragm booster actually would contact the valve cover. This one is only 9" or so in diameter so there's that. Second, my old one had a few leaky master cylinders on it and needed to be replaced. Third, I am converting over to a C3 Corvette master cylinder to work with my rear disc so most of this stuff needed to come apart and custom lines made anyway as this booster positions the master in a slightly different location.
I am under no illusion this will completely solve the brake feel issues and may need a vacuum reservoir or pump to do that with the current cam but I am considering going back to my old cam which didn't create these problems and will likely work well with this booster.
Update: This ended up working pretty well for a bunch of parts from four different cars (C4 front discs, LS1 rear discs, C3 master and late second gen F body booster). I am attributing most of the improvement to the booster. The stock pedal ratio works well with the 15/16" C3 brake master but if I had it over to do again, I would probably go with the 1" bore master to reduce the pedal travel a bit. Pretty much out of the box, the set up is an improvement over any stock second gen. I am sure with the 1" master and some better pads the system would be optimized.
