Put a new 268 XFI cam in my engine over the weekend. Just starting to retune the EBL and to my suprise it has less vacuum at idle than it does at higher RPMs. At idle it has about 70kpa and goes up to about 40kpa with increased throttle. This seems *** backwards to me. Anyone else experience this or have experience with this cam? Do you know what vacuum you have at idle with that cam?

 

Thats normal. My car is the same way. I have about 12-15 inches at idle and it will go up to 20 or so when revving it up in park. It doesnt take much throttle to rev the motor up in park so it will make more vacuum.

 

Yep, completely normal. Mine idles at around 10".


If you start having issues with the brakes i'd bump the idle speed up by 100 RPM till they work fine. I started off at 950 RPM pulling 6", 1100 RPM hovers around 10".