Hello. I recently purchased a 1972 280se 4.5 in good condition. After I finally got the engine started it had a noise like a lifter was clattering. I changed the oil to Castrol high mileage 20W 50, and it still made the noise. I then removed the valve cover and started checking lifter clearance, and sure enough I had a loose one. Number one intake was loose. The service manual said that all I had to do was adjust the 17mm adjusting screw to the proper clearance. I tried to turn it, but it wouldn't budge. The book doesn't mention loosening the 24mm compensating element. It looks to me like it is a 24mm lock nut that has to be loosened before adjusting the 17mm adjusting screw. What is the correct procedure for adjusting the lifters? Does it have mechanical lifters or hydraulic lifters?

The ball studs are mechanical adjustment and you don't need/want to touch the bottom nut. It should be firm, but the 17mm nut will move the ball stud up.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

1) On your engine the valve adjusters are mechanical, not hydraulic. The term "compensating element" is generally understood to mean the hydraulic type of pedestal.

2) The 17mm adjusting screw can be very tight in the shell: the threads are an interference fit in the shell. The 24mm is not a lock nut; it is the shell. A thick walled crows-foot in 1/2" drive is often the best tool.

3) Clearance measured between cam & follower cold: I .004", E .008"

Thank you very much for the help. It was most helpful...

One more thing....

After many, many adjustments the adjustment nut gets loose in the threads of the shell. Mercedes has a special tool for adjusting the valves that lines up with a torque wrench so you can tell if the resistance the adjusting nut is putting up is tight enough to hold the nut in place.

When the nut gets so loose it will not meet the torque it is time to replace the shell that is holding the nut. That is why the shell is there; so it can be replaced when needed. Otherwise you would have to pull the head, get a machine shop to chase the threads, etc......

I am sure this type of adjustment is covered somewhere online if you wish to see how it is really done, but this is, at least in my experience, not something you need to do each time you adjust the valves. The adjusting nuts has to be pretty easy to turn before it is time to replace the shell nut.