Why did the valve lash change in 2006?

[AH64ID]

I am prepping to check the valve lash on my 05 and my dads 06 later this month, and I have noticed that the 05 is 0. 010/0. 020 and the 06 is 0. 010/0. 026.



I have seen it before, just never a reason as to why. AFIK, there is no difference in valves, cam, pushrods, etc.



My only thought is that with the extreme EGT's of the 04. 5-07 motors they were having issues with the valves expanding, and the tighter tolerance being too tight and not letting the exhaust valve close? Or was it to shorter then duration for emissions without a cam change?



I have read some other threads where people are getting better response, power out of tighter valve settings, by making the exhaust duration a little longer.



Aftermarket cams use the same 10/20 specs on any 5. 9, so what am I missing?



I plan to set my truck at 8/18, would there be any reason not to do this on the 06?

 

[CKelley1]

it took me two years to get the answer. i finally got a cummins engineer that knew the answer. cummins designed the 06 for 0. 010 and 0. 020 chrysler was borderline on one spec with the in-cylinder egr used on the 04. 5 up, they changed the exhaust valve to 0. 026. you are on the correct path. by getting rid of most of the in-cylinder egr you can gain 6 mpg. change the cam to a pdr or colt stage 2, 50 hp nozzles and a smarty jr set on economy tm4 tq4

 

[Prairie Dog]

I can tell you that after adjusting my valves I saw no change in performance or FE of any kind.

 

[Wingate]

yep... increasing the exhaust valve lash is to give the valve face more contact "time" with the seat... . that is when heat is transferred from the valve face to the seat/head to be dissipated by the cooling system.

Insufficient valve clearance usually leads to burnt and/or guttered valves and valve face breakage. .

I would think if you have the aftermaret camshaft in the 06, you should run the valve specs mandated by the camshaft manufacturer

 

[AH64ID]

It's my dad's 06, which is 100% stock on the motor.

Thanks CKelly, makes sense and is what I figured.

I haven't talked to many people who have seen much of a difference on CRs, but on mechanical motors its more prevalent. I am guessing the change is there on CR's just not as noticeable. In any case the peak performance isn't effected, just spool/smoke.

 

[cerberusiam]

Its always an interesting discussion when the the reason for the valve lash change is brought up. It gets even more interesting when the person expounding the valve to seat time gets asked pertinent questions like just how much extra time the valve spends on the seat with . 006 thousandths gap change, how much energy can actually be transfered in that small amount of time, and what the actual temp difference in the valve is. Deer in the head lights EVERY time. :-laf



Considering the valve spends most of its time on the seat anyway and running the math on . 006 more lash with a basic heat transferance rates on typical valve materials, yeah well, the final number is less than impressive. It makes a good explanation though.



What makes a lot more sense is the valve compostion was changed to handle the higher extended temps better which resulted in a higher expansion rate that requires the extra lash, or, it was found the extra lash was needed for the existing valve composition.



It was noted some time back that a vlave composition change was made in 06 but not much was ever made of it. Hard to tell without a metallurgy test if that is actually true or the valves were just faced differently.



Mwilson you listening? Wonder if there is any change in part numbers on valves over that period and if a composition change like that would even trigger an OE # change.

 

[mwilson]

Its always an interesting discussion when the the reason for the valve lash change is brought up. It gets even more interesting when the person expounding the valve to seat time gets asked pertinent questions like just how much extra time the valve spends on the seat with . 006 thousandths gap change, how much energy can actually be transfered in that small amount of time, and what the actual temp difference in the valve is. Deer in the head lights EVERY time. :-laf



Considering the valve spends most of its time on the seat anyway and running the math on . 006 more lash with a basic heat transferance rates on typical valve materials, yeah well, the final number is less than impressive. It makes a good explanation though.



What makes a lot more sense is the valve compostion was changed to handle the higher extended temps better which resulted in a higher expansion rate that requires the extra lash, or, it was found the extra lash was needed for the existing valve composition.



It was noted some time back that a vlave composition change was made in 06 but not much was ever made of it. Hard to tell without a metallurgy test if that is actually true or the valves were just faced differently.



Mwilson you listening? Wonder if there is any change in part numbers on valves over that period and if a composition change like that would even trigger an OE # change.

Should be able to tell using your '05 vs. my '06.

Do you have your ESN handy???



Mike.

 

[cerberusiam]

That was fast, I will PM it to you.

 

[mwilson]

The results are in... .



The exhaust valves are different between the EPA 05 and EPA 06 engines.



The valve seats are the same part number though.



Bill of materials for Cerb's head was dated June of 2003. Takes a 4955210 exhaust valve kit.



Bill of materials for my head was dated April of 2005. Takes a 4955212 exhaust valve kit.



So as a result the Reman Cylinder Head part numbers are different as well.



I also that I noticed is the 03-05 engines show two different cylinder head gaskets, Grade A (1. 18 mm) and Grade B (1. 25 mm)



The '06 only shows one head gasket choice.



Mike.

 

[AH64ID]

Thanks guys!

It looks like we shouldn't take the valve lash too tight on the old man's 06, thou plenty of aftermarket cam's say . 020 regardless of the year.

 

[cerberusiam]

If he is bone stock and not using a Smarty then I would go with the stock setting. With a Smarty the . 020 setting is probably just fine and monitor the EGT's so they don't get as high as stock.



Too loose is better than too tight on an emissions engine.

 

[AH64ID]

It's a stock motor with a Smarty Jr that lives on SW1, timing only. He doesn't let the EGT's break 1300°, let alone 1250°.

I agree on the loose vs tight, and if it were my truck I would set it at . 020; however, it's his and I tend to be more conservative. . 021 is acceptable, and what's . 001!

I still have a few weeks to decide and appreciate the info.

 

[cerberusiam]

. 021 is acceptable, and what's . 001!

LOL, I don't think the . 006 is even that critical considering how he drives but ya gotta make pops happy.

 

[S.Morris]

I think Cerb hit the nail on the head for the change in lash measurement.

In setting lash tighter than recommended setting don't forget that in addition to heat/expansion the other reasons that lash gets tighter is valve seat recession/wear and valve stem elongation.

 

[CKelley1]

if you give the ein # of the 06 to -- email address removed -- cummins will tell you to set it at 0. 020. the engineer i spoke to said it was to help trap a little more exhaust gas in the cylinder. one truck has about 60,000 miles at 0. 026 and about the same at 0. 020. all of my 06's have pdr cams after i got the info i set them back to 0. 020. it maybe my imagination but i think it sounds better at 0. 020. one thing did come out of this, i can now change the settings in 30 minutes from time i start to time i put tools up

 

[AH64ID]

I haven't looked at quickserve with an 06 ESN in a while, but I do recall it being 0. 020.

 

[Wingate]

Its always an interesting discussion when the the reason for the valve lash change is brought up. It gets even more interesting when the person expounding the valve to seat time gets asked pertinent questions like just how much extra time the valve spends on the seat with . 006 thousandths gap change, how much energy can actually be transfered in that small amount of time, and what the actual temp difference in the valve is. Deer in the head lights EVERY time. :-laf



Considering the valve spends most of its time on the seat anyway and running the math on . 006 more lash with a basic heat transferance rates on typical valve materials, yeah well, the final number is less than impressive. It makes a good explanation though.



What makes a lot more sense is the valve compostion was changed to handle the higher extended temps better which resulted in a higher expansion rate that requires the extra lash, or, it was found the extra lash was needed for the existing valve composition.



.

I can guarantee you that if you run insufficient valve clearances, you will burn a valve... The industry where I work this situation comes up from time to time... really want to keep up with the state of the valves, run a valve recession check. . Of course, you would need a baseline from back when the engine was newer. If you really wanted to spend the $$$ you could opt for a beta analysis, it will detect any and all wear in the engine.

????... these are 4 valve engines, do they have adjustable valve bridges or are they non-adjustable?. .

 

[cerberusiam]

I can guarantee you that if you run insufficient valve clearances, you will burn a valve...



these are 4 valve engines, do they have adjustable valve bridges or are they non-adjustable?. .

Sure, thats a given. Same with checking the installed height of the springs and valve stem to catch seat wear or other problems.



However, insufficient lash is not the same thing as more lash to keep the valve on the seat longer to transfer more heat. The basic concepts are not even the same. The reasoning that a valve that spends the bulk of the time on the seat is going to see a major benefit of the increased time attributed to . 006 lash change is lacking.



Even the idea that the valve can grow more than . 020 is hard to fathom let alone enough that . 006 really makes a difference?



The bridges are not adjustable, just the rockers.