One thing I have noticed a lot of difference in is valve lash. When you tighten the lash up (decrease the gap amount), you make the valve open sooner and close later. This allows for more air to get in and out. By tightening them up, the turbo lights sooner because more air is being shoved out at a lower RPM. This gives you a ton more efficiency down low from what I have noticed because boost helps burn fuel, when there isn't enough air, fuel is burned inefficiently. Inefficient burn can be compromised for less power by letting off and getting back into an efficient burn ratio, but this is inefficient in itself because you might be starting to go up a hill and you will either have to go up it slowly or maintain speed by giving it more fuel that will burn rich but get the turbo spooling eventually. Why should you ever have to wait for that turbo? Running the valves tight help out a lot, but there is more to it that I want to know. The exhaust valve is what drives the turbo sooner if you run it tighter, but what does the intake valve have to do with anything? Do they work hand in hand? As in to get more air out the exhaust valve do you need to run a tighter intake to get more air in? Is there any benefit to running it looser? One issue with running them tighter is you can only go so tight before the valve and the piston contact, which is not something that is very appealing Thankfully valves tend to loosen over time rather than tighten.

I do notice there is a change of note on the exhaust brake at high RPM's. Sounds almost like a valve tick but only at high R's. :shrug:Has bothered performance of the exhaust brake, towing,etc... Truck still keeps going!

Do you monitor back pressure?With my cam I can hit 60# a lot quicker than I could with the stock cam, and I wonder if the tighter lash will add more? I may have to adjust my EB just a hair.

Ok... I can say no I don't monitor drive pressure... So how do I adjust it then?

Ok... I can say no I don't monitor drive pressure... So how do I adjust it then?

Without a gauge you can't.

Say for instance I rig up my boost gauge to check drive pressure... So how could I adjust a Jacobs brake? Hmm.. Thinking I've got a 0 - 100 PSI water pressure gauge I could rig up in the pyrometer hole for testing purpose... So how would I???

Say for instance I rig up my boost gauge to check drive pressure... So how could I adjust a Jacobs brake? Hmm.. Thinking I've got a 0 - 100 PSI water pressure gauge I could rig up in the pyrometer hole for testing purpose... So how would I???

If your jake is like mine the rod that actuates the butterfly valve is threaded. You would simply pop the ball and socket apart and turn the socket end. But I wouldn't go more than a turn or two, or you may hinder flow when the EB is off.

I adjusted the valves on my dad's 06 last weekend. The intake valves were all about .012, and we set them for .010. I thought about .008, but as it's his truck and not mine I went with .010. The 2006+ trucks have .026 as the exhaust, but if you look the ESN up with Cummins it says .020. I did some reseach as to why, and came up with nothing. The valves are different for 06, but it's unkown if they expand more. The best guess is that they needed to tighten up the shot group on the emissions just a little and the additional .006 of seat time combined with .006 less lift would reduce the emissions just enough, this is supported by the .020 from Cummins. We decided to play it safe and not ignore Dodge 100%. We set them at .023 which splits the difference and is in the safe level for both Dodge and Cummins. We also installed an intake horn from GDP. The day after the mod my dad towed his 5K lb 16' stock trailer from Boise to Seattle. He said his peak boost was up 2-3#, which is not what I expected. With more intake lift/duration and the lower restricted intake horn I expected peak boost to drop 2-3#. When I moved my boost reference line from the OEM horn to the intake manifold I lost 2-3# because the restriction in the OEM horn adds boost. So we figure the added air from the horn, and tighter exhaust valves is more than the lower restriction from the tighter intake valves.