Re: Line lock question
 

Yes, I use a 2 pound residual valve in the rear of both the Camaro and Mustang (Aerospace 4-pistons).

Re: Line lock question
 

Pedal ratio should be 6:1 so if the pedal is 12" long from the pivot to the bottom you want the rod attachment at 2" down from the pivot.
I guess 2lb isn't much but most class racers don't want any drag on their brakes and have gone as far as installing springs to release the calipers so the pads don't rub the rotors. Since disc brakes don't have return springs there should be no need for residual valves unless the MC is below the wheel cyl and fluid could drain back. Residual valves on old drum brake cars were to stop the return springs from pushing back the wheel cyl pistons way back and causing a low pedal. Much of that was overcome with those strainer looking things in the wheel cyl on the wheel cyl springs. Which is why they did away with residual ck valves in factory MC's years ago even with drum brakes.
You can back bleed brakes pretty simple and easy. Go buy a large animal syringe and a piece of clear tubing to fit it. Load the syringe with brake fluid and remove the air, just like you saw the nurses do before they inject you. Push the fluid back thru the bleeder with the syringe. This is OK but I've never had to do it on brakes, only on clutch hydraulic systems that were hard to bleed.. On calipers tapping the caliper with a rubber mallet will bring the air to the top and out the bleeder. Be sure the calipers are installed correctly with the bleeders at the top. I have seen them reversed and the bleeders at the bottom.

Re: Line lock question
 

I have had issues with the caliper not being perfectly square to the rotor, causing the caliper to "move" or twist (just a few thousandths) but it was enough to affect the pedal movement similar to what you say, a bit "mushy" on the first hit.
After squaring the caliper to the rotor the problem went away.

Re: Line lock question
 

Give me a call at 650 922 0407 and I'll give a trick for bleeding disc brakes....

bob

Re: Line lock question
 

Yes. Had it happen changed the LL and solved