Clutch master cylinder volume

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davisw73

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Central Florida
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Davis
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1985
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C20
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6.5 banks turbo diesel, NV4500
So here's my dilemma. I have an 85 C20 that I am converting from TH400 to NV4500. I have stock 85 hydro master cylinder and 99 NV4500 internal slave. I have everything mounted, ready to go and it seems the square body master doesn't seem to push enough volume to completely disengage the clutch. I have it completely bled and have plenty of travel left in pedal. I can see the throw-out bearing immediately start to move as soon as I push the pedal and I can force a very small feeler gauge in between the friction disk and pressure plate, but when I turn the output shaft the clutch is still fairly engaged and drags bad enough where the only gear I can turn it in is 5th (doesn't turn motor).
Am I wrong on my theory about volume or is there something else I'm missing? Is this common and I missed it in the 30,000 threads I read about this conversion? Is there a bigger bore master that everyone uses that bolts in with minor mods? Can a 99 master be adapted to my 85 firewall without a ton of mods?
Thanks,
 

bucket

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How much stroke do you have on the master cylinder rod? I'm wanting to say that max travel is just under 1", but can't remember for certain.
 

mrgoodwrench

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mike
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Hmmm i know people using the 85 era master with the late model nv4500 slave with no issues so it should not be the master to slave ratio. But i dont know what else might be wrong.

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