[gforce66]

I am thinking about replacing my master cylinder (it is out of a 72 nova Disc/drum) and I need to know what size the bore is? Taking it out to measure isn't an option at this time. Hopefully there will be an answer with all of the big brains on here!!
Grant

 

[shawn63]

Most "manual" setups are 1.00" and power assist have 1.125" bores.

 

[gforce66]

Thanks Shawn, I am using it without a power booster now, but I can't remember if it had one when I got it. Is there a way to tell the difference without taking it off of the car?
Grant

 

[shawn63]

I don't think you can be sure of the bore by it's physical appearance. If you're limber emough you maybe able to measure from under the dash; the pushrod/ clevis is easily removable.
Also you maybe able to remove the mounting nuts on the firewall leaving the lines connected and pull the m/c forword enough to measure; usually there is quite a bit of "play" in the lines so as to allow you to do this. I know this from installing/removing fenderwell headers.