With the addition of bigger turbo and injectors, I thought a tighter spec. on the valve adjustment would be a benefit. Let more air in and more exhaust out, most likely a minor gain. I set mine at a loose 16 and 7 on the money.

I think the Cummins manual lets you go to 15 exhaust and 5 intake on the tight side and still be in spec.

With 90,000 on the clock it wasn't time, but it did make a noticable difference at idle. Smooth...

 

I'd actually go looser on the lash with a bigger turbo. It should help pickup the bottom end a little.

At least, it does on gassers.

 

Justin, I don't understand how that would work?