When is it prudent to do a valve adjustment??

I am coming up on a year from when I put my springs in and I think I am hearing some valve clatter. So on Friday I am going to check and adjust as needed. Just wondering with the Hamilton springs should I be adjusting every so often or should I not have to???

Also when I did the springs last year I set lash back to Cummins spec of int. .010 and exh. .026, and I an thinking of going to the old Cummins spec of .010 and .020.

Any reason why not and why Cummins decided with the CR motors to open the lash on the exh up some???

 

im interested to know as well, with my 170K so far.. stock engine tho..

 

i dont know why they changed it but i've set them to .008 and .018 and they run great.

 

They made the lash looser to open the exhaust valve later, this cut down the exh duration and gave the fuel longer to burn with retarded timing and the large piston cooling jets. It was a lot cheaper to loosen the lash than to have new cams cut. I would set them at .018" on the exhaust. That will be as good as you can get with a stock cam.

 

Valve lash is determined solely by the ramp profile. Or better, the "lash ramp"

The lash ramp is the mid-point between the opening ramp and the closing ramp near the base circle.

You cant arbitrarily change the lash setting on the CR cam's exhaust side without effecting wear rates and adding valve slamming issues.

The shorter duration of the lobe on the CR exhaust side has forced all three ramps to change from previous grinds. Opening, closing and mid-point ( the lash ramp ) Use the sloppier settings and have the least wear and best chance of NOT dropping a seat from vibrating the valves/seats.

 

Any negative side effects of running .018 on the exh? Increased lobe wear etc.?

 

Sorry Don, I replyed before I read your post. Which is better the .026 on the vc or .020 of the 24v???? I have been told by a few in my area that say .08/.018 for lash. You say the tghtet lash will or could wear the cam out faster and run the risk of dropping a seat???

What is different with the cam profiles between the cr and 24v that dictates the looser lash?

 

That can't be further from the truth. We have all kinds of different cams for all the various ISB and QSB engines from marine applications, industrial, automotive, to power generation applications. I am not sure how many different cams we have for ISB and QSB series engines but it is a lot. I bet we have 10 different cams in our parts warehouse that we keep in stock not to mention all the other oddball 1 off CPL's that have different cams that we have to order in from the factory. And to say that the ISB that is in the Dodge Ram which is the largest volume CPL of the ISB/QSB engine would have a valve set procedure to save money is actually pretty funny.

Now I have made valve adjustments on my quad back in the day and set the intake .001 tighter and the exhaust .001 looser to get a little more outta it, but to say that Cummins will change the entire overhead procedure to save a buck...uh...no.

Just set the overhead to what the engine tag says. Go too tight with you valve sets and over time if and when some carbon start to build on the pistons you could run into issues. Plus valve adjustments tend to tighten up rather than loosen over time due to the valves beating into the seats.

 

Oh and too loose the crosshead can fall out

 

Hecked them yesterday and all of them are good to go. None of them went out of spec within the last year.

All intakes were .010 and all exhausts were .026, so I guess Im good to go.