Vacuum gauge

Would like to install an old Motor Minder vac gauge in my ;55 GMC. I don't have a separate source for vacuum. Should I tee into the power brake vac line? PCV vac line? or vacuum advance line? Don't have a fitting or plug in the intake. Looking for a clean connection. Would the above listed sources work? Thanks for the help. Kent

 

any place that is convenient.

 

So if I tee the vac. advance line I won't mess up anything with the distributor? I guess it's a closed line right? Thanks

 

right

 

ok will give it a whirl. Thanks, Kent

 

If it's not a closed line there's a leak.

 

Yeah, I've got a Sun Vac-O-Meter in my Comet and I pay closer attention to it than any other gauge in the car.

 

Does the GMC's distributor vacuum advance source only pull vacuum when the butterfly opens like most early vacuum advances do? If so, wouldn't it be the wrong place to install a gauge? I have always installed the gauge on a "manifold" port where it can monitor true manifold vacuum, low gauge number means throttle open, or under acceleration, high number was fuel economy.
Just asking

 

No "most" vacuum advances get hooked up to manifold vacuum on the engines that we are talking about. Some Fords up to 56 used a different vacuum source but all the GMs from the 50s/60s are manifold vacuum and all the vacuum does is pull on a diaphragm to change the advance a spring retards it when the vacuum drops.

 

Tommy, so teeing into the vac advance line that comes off the carb will still be ok for my vac. gauge?

 

Sure as you watch the needle on your gauge fluctuate back and forth, the vacuum advance is doing the same thing inside the distributor.

 

Yep, make sure you tap into manifold vacuum, not ported.

 

ok thanks again.