On Tue, 21 Jul 2009 12:03:46 -0500, Tim Wescott
wrote:

I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the Camero
bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

TIA.
You need the same overall mechanical advantage - main thing is the
bore of the master cyl - assuming the leverage on the pedal is the
same.

Measure the bore of the clutch slave and the master of the original
install - calculate ratio. Then calculate the mechanical advantage of
the clutch pedal as a lever. Multiply them for the total MA.

If your replacement setup is close, you are OK. Low MA makes a heavy
pedal.