Master cylinder and booster problems

[BIGBRUDDA]

Earlier this summer the brakes on the Daytona(86) started fading .Eventually goin all the way to the floor.
According to the FSM test procedures I had a bad master cyl. No leaks, new pads, shoes, and wheel cyl. So I've replaced it with a 24 mm MC and dual diaphragm booster, specd for an 89 Shelby Daytona. Now no matter how much I bleed. 1st stroke still to the floor with warning lite,2nd stroke better with warning lite,3rd stroke better no lite, 4th stroke firm, but low pedal posistion.
I've read and re read,and followed FSM procedures ,repeatedly. No differance. So what gives??
I did notice a notation in the parts descriptions regarding 2 different "actuator rods".Whats that about?

[speedfreek500]

Did you bench bleed the master? They are 2 different actuator rods because they are both different lengths. Is the brake sitting up the same height as it was before the master swap?

[2.216VTurbo]

Did you replace calipers? If you did is it possible left on the right and right on the left? I did that on my GLHS 20 years ago...That leaves the bleeder screws too low to bleed the air out of the top of the calipers.

[wallace]

Rear brakes out of adjustment can also be a cause.

[BIGBRUDDA]

Only replaced the mastercyl/booster,and bench bled twice.New pads and shoes, adjusted till contact made with drum.
Gonna explore the actuator rod/ pedal posision today.

[BIGBRUDDA]

Ok, well the brake pedal is about 1in lower than the clutch pedal.
The parts diagram at Rockauto indicates two different booster pedal rods codes. A #13340 for the 3.5in single diaphragm 230mm unit. And a#13992/14921/14928 for the 6.5in dual diaphragm 200mm booster. My old booster has no code markings on the rod at all.
Are there 2 different brake pedals? Apparently the 6.5x230 unit fits just about all the FWD cars made.

[ScottD]

1) Make sure you bench bleed the master cylinder before installing.

2) Make sure you bleed the brakes in proper sequence. Most of these cars have a diagonal braking system, which means you have to start at the furthest wheel away which is the passenger side rear. Then bleed driver's side front, then driver's side rear, then passenger side front is the last one. It can take a lot of pumping to get all the air out of the system.

I really think your problem is due to one of the above, not a parts issue.