[flipper35]

I was checking the vacuum on the 4160 to try to get the highest vacuum reading while adjusting the idle mixture. Turning the idle mixture didn't really change anything, but when I pulled the plug on the vacuum port to put the vacuum guage on, the idle went up 200 - 300 rpm.

I get about 9.75 inches at 1100 rpm idle, which makes me think there may be a vacuum leak.

Cam is 292 duration on both lobes and 106 degree centerline.

The idle is fine, doesn't get hot, but it does seem to load up a bit. I am happy enough with it, and this may be the best it gets with this cam.

I mostly want to know why the idle would go up when the vacuum port is open?