tnt76vette

Vacuum Gauge on my '76 350 w/mild street cam pulls down to 16-17 or so, when hooked to distributor vac. advance, at idle. Is this good, bad, or ugly? Thanx in advance for any and all replies......TNT76VET

Smokehouse69

16 or 17 is fine as long as it is fairly steady. Your mild cam probably cause your vacuum to be down a couple of inches. With a grocery getter you can expect about 19-21 inches on an engine in good condition and tune.
Make sure you check it from full manifold vacuum, don't trust you advance line, it is probably coming from a ported vacuum source on the front of your carb.

bence13_33

I agree with smokehouse, 16-17 is just fine.

PatG

If it is 16 or 17 you need a bigger cam :)

No, really it sounds fine. For a point of reference I have a comp cams magnum 270H and I tune the motor in right at 15" of vacuum. All of the vavuum operated stuff sill works fine. I wonder how low the vacuum can go before your brakes and headlights stop working right???


[Modified by PatG, 11:34 PM 2/9/2002]

1979toy

Uhh, great vacuum, but why are you getting it at the dist. at idle? The dist. should be getting no vacuum at idle. I think that it's the drivers side port on the front of the carb. that is for the dist. Should be no vacuum befoe 1200 RPM or so.

427V8

Yea a bigger cam will bring that vacuum down, a good high duration cam will have less than 10" vacuum...:smash: :smash:

Larry B.

Sounds about right for a mild cam. It may be lower in gear if it is an auto. :chevy

tnt76vette

Thanx to All....FYI I hooked into back of carb at a small hose where my distributor hose goes........