Valve Lash

[Mopar1973Man]

I've just learned that valve lash that is done wrong or in a hurry and I didn't verify my measurements can have impacts on performance, idling, and lope. Just a few days ago I figured I would just verify the lash and cold engine I was having issues getting feeler gauge to pass on a few cylinders. I ran the head again and verified all my measurements after torquing the lock nuts. Now after a few days my lope at idle is gone. Performance has improved slightly and even the MPG is up slightly. So I've got to admit this was my bad but I wanted to share my mistake to hopefully help other spot weird performance issues and check the basic things that might cause issue. 

 

I remember I was in a hurry install injectors and ran the valve lash quickly and the mistake cost me a world of weird issues that never seemed to go away no matter what I did.

[Dieselfuture]

That's weird, how far off were you. Cummins claims there is a pretty big gap something like 14 to 25 thousands is in spec. Don't quote me on exact number but it's pretty wild. 

[Mopar1973Man]

Yeah I know intake is like 0.006 to 0.015 and exhaust 0.015 to 0.030 don't quote my span I'm going from memory.

 

My mistake I made was set the lash. Snugged the lock nut. Grabbed the torque wrench torque everything again but never checked the gaps. So the ones that turned just a weebit was the ones most likely too tight. Again my fault for being and a hurry and not checking my work.  (Bad Mopar!) 

[Dieselfuture]

I've never used torqe wrench on my valves I probably should. I always get close to filler guage and then I get nut close to being tight and then I move nut and allen at same time, I was told that way they never come lose. Worked every time for me. But it may take few times to get it right. 

[Mopar1973Man]

Trick... 

 

If the gap is a bit loose twist both the allen and the nut together tighten. 

If the gap is bit too snug the twist the allen loosen as you tighten the nut. 

 

You can gain or lose gap measurement with this trick.

Edited September 18, 2017 by Mopar1973Man

[dripley]

Just speaking personally others mistakes help me turn a possible mistake into a success. Seeing others mistakes here has helped me greatly when tackling something new to me. Another reason I try and share my mistakes. Just another aspect of this site that has educated me. Keep it up.

[Mopar1973Man]

2 minutes ago, dripley said:

Just speaking personally others mistakes help me turn a possible mistake into a success. Seeing others mistakes here has helped me greatly when tackling something new to me. Another reason I try and share my mistakes. Just another aspect of this site that has educated me. Keep it up.

 

Exactly... Yeah, I feel stupid finding this mistake and glad there is no damage to the engine. Sometimes you got to swallow your pride and voice your mistakes so others might learn from yours. 

[dripley]

1 hour ago, Mopar1973Man said:

 

Exactly... Yeah, I feel stupid finding this mistake and glad there is no damage to the engine. Sometimes you got to swallow your pride and voice your mistakes so others might learn from yours. 

[kzimmer]

So while on the topic of valve lash, has anyone experimented with settings deviating from stock 0.010" / 0.020"? Results?

 

 @Mopar1973Man, do you know which valves were too tight, and how tight? I'm just curious if there's any experience out there with different settings. I'm sure I've read in the past people using different lashes and claiming some sort of gain.

[Mopar1973Man]

I ran 0.008 and 0.018 on the last time. The only problem was like I said before...

23 hours ago, Mopar1973Man said:

My mistake I made was set the lash. Snugged the lock nut. Grabbed the torque wrench torque everything again but never checked the gaps. So the ones that turned just a weebit was the ones most likely too tight. Again my fault for being and a hurry and not checking my work.  (Bad Mopar!) 

 

When I checked with a 0.008 and 0.018 some didn't pass. Too tight yet on a cold engine... 

 

Went back to 0.010 and 0.020 for setting this time and doubled checked after torquing the lock nuts.

Edited September 19, 2017 by Mopar1973Man

[dripley]

I set mine at 6 and 16 150k ago and never saw any difference in anything. I checked them about 30k ago and they had not changed much but again I never noticed any changes in how the truck performed at all.

[Mopar1973Man]

I think my changes are because of the ramped up timing I'm running with Quadzilla. I'm running 21.8* to 22.1* degrees of timing at 65 MPH. My EGT's are lower and boost is low but the cylinder temperatures are higher. This is seen in my coolant temperature which is about +5* warmer now because of more fire in the cylinder and less blowing out the exhaust port. So I figure the expansion of the valve stems filled that gap up and was not stay close long enough to idle right while hot. Never had a problem with cold engine only 100-110*F day after driving 2 hours it will lope and nearly stall some times. 

[Dieselfuture]

I don't know but it almost sounds like a vp issue 

[Mopar1973Man]

2 hours ago, Dieselfuture said:

I don't know but it almost sounds like a vp issue 

 

Nope. All I got to do is turn off the Quadzilla and watch it all change up. The timing drops back down to minor 13* to 14* at 65 MPH EGT's rise up another 100*F and boost rises almost 2-3 pounds. No VP44 issues just tuning the engine for better MPG's.

 

Here really soon I might release my Quadzilla tune for others. When the Quadzilla crosses over my 165*F warm up limit while cruising I find myself lifting my foot off the throttle before of the surge of timing that brings on more power. GPH flow rates drop and MPG rises. When I've had one trip now down and back from Ontario, OR and on a 1/4 tank fuel for over 270 miles. Not bad.

 

As for the lopey idle and stalling, I thought the same thing being I've already changed 3 sets of injectors. Being the VP44 was still under warranty. Now after the valve lash it all changed again now very smooth idle, no more lope at idle, stalling non-existant like previous. 

Edited September 19, 2017 by Mopar1973Man

[Dieselfuture]

If it wasn't for this site, I probably would of sold the truck by now and not been any better of with other junk out there. I was ready to change the vp 3-4 years ago do to my surge but discovered other issues that contributed to that surge, like ac noise and injectors. Every once in a while I still get that very faint surge but nothing like before. So between all the things I learned here is a big part of the reason I still have my truck. That and it's paid for.

[dripley]

Same here brother.

[Mopar1973Man]

Still learning every time something screws up or fails. 

[Dieselfuture]

We'll be done learning when we're dead

[dripley]

Told my son he would drive me to the cemetery in the 02 on my last trip. He tells it better be running good or he is going to call ahead and have them dig a bigger hole. Me, just to get the last jab in, it will be running top notch even if it kills me. AAAHHHH HA HAAAAAAA!!!!!