Quick help on Firewall adjusters...

The firewall adjuster is to adjust the amount of travel in the clutch pedal. You don't need to check it from underneath. You can just go by pedal travel.

Turning left raises the pedal - increaseing the distance of pedal travel required to dis-engage the clutch
Turning right lowers it - reducing this distance.

You want to lower the pedal enough so that the pedal doesn't have to travel very long to completely disengage the clutch but you dont want to lower it so much that the clutch isn't copmletely disengaged.

Before I got the adjuster, my clutch disengaged at the top 1/4 of pedal travel (or about 6" or so from the floor), making the remaining 3/4 of travel wasted time between shifts. The hsop that installed it adjusted the pedal down so that when the clutch disengaged, the pedal was only about 2" off the floor.

I hope this helps.

You will know if the pedal is too low by a few different symptoms.

1) If the car is harder to shift even with the clutch pedal all the way down.

2) You smell burning clutch when you are sitting still with the clutch pedal down and the car in gear.

I never adjusted my clutch pedal this low but my first adjuster didn't have a jam nut and over time, the thing would rotate to the right, lowering my clutch pedal to the point where the tranny would grind at any gear change

I was able to get my clutch pedal almost level with my brake pedal.