So, I'm pretty sure I've got the pedal thing sorted out. I have at least 30 hours invested in this, probably more. I've been in and out from under the dash countless times.
I've spent way to much time on this. SST's literature on this says it's a no hassle "perfect fit" install. It's not so far. It seems that the early B Bodies are the bastard child. There is no way that this part of the kit was properly engineered to fit my 64.
Researching the internet, and studying the attached material for reference, I have done my best to resolve my pedal issues. All the material I read, suggest a 6.0 pedal ratio as being optimum.
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https://www.mcleodracing.com/blog/how-to-calculate-pedal-ratio-for-hydraulic-linkage/236
See last images of pedals at bottom of page.
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Clutch linkage math - how to
The first photo in the above link was very helpful.
I've fabricated several templates to assist me. In the end, this is what I've come up with.
I moved the master cylinder as far up as possible on the firewall, just below the brake master cylinder mounting plate. I retained the original supplied master cylinder firewall mounting bracket.
Next I removed the OEM clutch pedal arm and fabricated my own arm. In the arm I drilled 3 holes at the following radius's from the pivot point - 2.25 inch (6.4 ratio), 2.875 (5.0 ratio) and 3.125 (4.64 ratio). All allow for 1.4 inch master travel.
Attaching the rod at the 2.25 position (6.4 ratio), results in slight internal bore to piston friction in the last .375 of travel.
Attaching the rod at the 2.875 (5.0 ratio) position, the piston travels freely, without friction / internal interference
Shimming the upper bolt between the firewall adaptor and the master cylinder .225, resulted in changing the master mounted angle. This resulted in being able to use the 2.25 pivot point without friction. This means I am able to use a pedal ratio of 6.4 (preferred) as opposed to 5.0.
I made a beveled adaptor to attach to the firewall mount, .250 thick at the very edge and inserted it between the master and the firewall adaptor. I had to elongate the upper mounting hole in the master to be able to insert the bolt into firewall adaptor. My homemade adaptor slightly skews the bolt angle.
I now have perfect cylinder bore alignment at the 2.25 attachment, which gives me what I was looking for a pedal ratio of 6.4.
SST did send me a new adaptor which seems to work, but it's very bulky and it hits the brake line junction fitting. It will connect to the factory arm, but the resulting pedal ratio will still be only 4.64 - far from ideal.