Engine Valve Adjustment

[JMLambert]

I have 135K miles on a rebuilt short block with 235K on the truck. It sounds like the valves are starting to clatter at a higher rpm. When should they be adjusted and how hard of a job is it? Thank you in advance, John.

 

[Cummins12V98]

IMHO it’s not a hard job. 150k is the suggested interval so I would do it now if you think they sound loose.

 

[JMLambert]

Thank you, John.

 

[Topzide]

Not sure of the valve lock nut is like but after doing mine, I made a tool for the next time! I took a socket and Tig welded a rod to it so that I could put allen key through the socket. Next time should go a lot easier than this past time. I always hit yard sales for old tools to cut and make special tools for different applications! I made a wrench that had a 3/8 open on one end and 9/16 box on other end. That way only needed 1 wrench to carry instead of 2. Use HF tools for some of those things also. Next hack will be to cut adjustable wrench head off and remount it 90 degrees to handle. Would help in many different ways. Good luck on the valves and keep it running!!

 

[JMLambert]

Thank you, John.

 

[Gary - K7GLD]

I wonder what the "average" cost is for a 24 valve adjustment these days?

 

[Dl5treez]

The Mopar1973Man site has a great write up on it, complete with excellent photos.

https://mopar1973man.com/cummins/ar...tion_50/51_engine/valve-lash-adjustment-r455/

.010/.020 is the default stock spec, there has been chatter over the years of going tighter (.008/.018) for better top end performance and looser (.012/.022) for low end, but it was splitting hairs, really. It takes me about 30 minutes not trying to speed but confessionals that I wrench for a living; figure an hour or two if you have the tools and like to tinker. Shops are going to probably charge a minimum of 1 hour...

 

[Cummins12V98]

Use the pulley nut on the alternator to turn over the engine.

 

[Vaughn MacKenzie]

It has always amazed me how wide of range Cummins allows on valve lash, pretty sloppy if you ask me. I have adjusted the valves on every one of my trucks, even within 25,000 miles of new and found ALL had room for improvement. Once set, 100K is fine, but I would not go past that.

When adjusting valves get them as darn close to each other as possible. It will amaze you how much smoother your engine will run. I always go with .008 intake, .016 exhaust. But if you are running serious horsepower, stick with the factory .010"/.020".

 

[slowmover]

It has always amazed me how wide of range Cummins allows on valve lash, pretty sloppy if you ask me. I have adjusted the valves on every one of my trucks, even within 25,000 miles of new and found ALL had room for improvement. Once set, 100K is fine, but I would not go past that.

When adjusting valves get them as darn close to each other as possible. It will amaze you how much smoother your engine will run. I always go with .008 intake, .016 exhaust. But if you are running serious horsepower, stick with the factory .010"/.020".

A Lamborghini is great until you gotta try get it in with Tony to balance out those Webers again. (Have to have factory training. Be Italian. Catholic. P3 Mason. Cast spells).

Glad ours is more tolerant. (Nice heads up to not be sloppy in failure to check)

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