well here goes

well guys it is finally feeling like spring here so i decided to start tuning my car, well i hooked a vacuum gauge up to the full vacuum port on my holley 4160, vacuum at idle in park is roughly 15-16 inches, when in gear however it is like 10-12 is that normal i have always heard that vacuum below 15 meant questionable brakes is that 15 inches minimum IN or OUT of gear automatic of course, thanks for the help, the car deos have a lupy idle and always had the person i bought it from said it had a cam but didn;t have the cam card or anything else. thanks

 

It's normal for the vauum guage reading to drop some when the car is idleing in gear. The bigger the cam the lower the vacuum reading.

What you're getting sounds ok.

 

Vacuum is measured at idle regardless if it's in gear or not. If you have 15"/Hg in neutral at idle, then 12"/Hg in gear then you have 12"/Hg at idle. That's what your car will idle at while you're driving, right?

I've run less than 15"/Hg, more around 11"/Hg and I didn't have problems, but that's just my experience.

 

thanks for the info guys