I was just reading in HR and CC's "200 Power Performance Tips" mag. from years gone by and ran across mention of using the Vette manual m/c GM PN 18001118 for our cars.

Does anybody know what the piston size is???

And since it is a manual unit, we shouldn't have any problems with the pushrod falling out...

Please come back... pdq67

PS., and as funny as this sounds the pic. of it looks almost like the big 1.25" piston M/C that I am bound and determined to try... The sucker looks rounded or bloated, like a "Toad/Frog", if you know what I mean by over-sized...

Nope, it's a 1" bore according to books I have.
It doesn't show GM part numbers though.
David

I gathered some information about a year ago for a guy on this site regarding manual master cylinders. This is what I found back then when I was doing this.

1968-1976 Corvette - w/ manual disc brakes (1" bore)
AC Delco - 18M27
GM - 18030269

It seems that your part number is no longer availible, most likely superceded by this one. I just check the price of 18030269 over at www.partszoneonline.com (http://www.partszoneonline.com) and the price is $65.32 and no core charge. This is a good small dealership with great prices if you are looking for parts and unlike some other online GM parts places these guys ship UPS and don't gouge you for shipping, you pay what it costs to ship, not a flat rate. The parts manager, his name is Bill, tell him Bryan Shook sent you. The dealership is down the street from my house, I've used them tons; good guys.

I bought one a few weeks back, and still have it. I got it for about $30 from a local Autozone, they even had it in stock.

I am using the PBR dual piston Vette calipers on my car, and this master does not generate enough line pressure to work well. You really have to leg it. I switched to a 15/16" unit, and it helps, but what I really need is a 7/8". I have not been able to find one with the deep pushrod hole, if anyone know of one, please drop me a line. If you are using a different type of caliper, it will be different.

By the way, if you are interested in the vette' unit, let me know. Cheap, and less clutter for my garage!