i just intalled hks 280's. my vacuum use to read 16 to 17 now that i out the cams in it around 10 is that normal?

 

Yes, when you go to a set of cams with a lower centerline and more overlap the motor will make less vacuum at idle. It is compleatly normal, now you just need to get tuned.

 

^ +1

 

I went from 18 vac to 16 at idle after the tomei cams.

 

the poor vaccum is what gives the motor the "lumpy" sound everyone always loves so much.

 

yes it's normal, and I heard that losing vacuum might hurt braking performance if you brake in neutral, leave in the gear will be ok.

 

btw, your title should be "loosing vacuum" not "boost question", it has nothing to do with boost.

 

totally normal

 

thanks guys!!

 

I have HKS 280/272 and mine will idle at -9 or -10. With adjustable cam gears you can dial in a smoother idle. I imagine that your cams are installed straight up. If you were to retard the cam timing you could achieve a smoother idle.