valve adjust screw wear

[Gary Ihas]

I have severely worn adjustment screws on 2 exhaust valves (cyl #1 and 3). The centers on the ends of the screws have worn to a deep (1mm) cup shape, with a ridge developing around the circumferance. The valves were last adjusted about 1000 miles ago.
I had the heads rebuilt by Mark Stephens.

Anybody seen this before, and what should I worry about?

[Dave at Pelican Parts]

I've seen it on my high-mileage 2.0. Mileage is unknown, but presumed at least one rebuild on them. I replaced all of mine just in case. No problems as yet, but I don't have many miles on it so far.

It might be caused by simply using the old adjusting lugs. Or it might be caused by the valve tips being too hard--though with the stories of MSHP's SS valve tips mushrooming that I've heard, I would find that hard to believe.

--DD

[mkinne]

Just curious...

Is it possible for the adjustment screws to wear a hole into the rocker arms? That could make checking valve clearance difficult / inaccurate.

Matt

[Dave at Pelican Parts]

I can't see how it would ever wear a hole in the rocker arm. The adjuster, after all, is threaded *through* the rocker arm.

The adjuster itself can gall and wear (Jon Lowe, in last month's Panorama, said they should be replaced every rebuild for that reason) and/or it can wear the tip of the valve--the part it pushes on. I have some of each as "souvenirs". But I can't see how it would wear the rocker arm itself.

--DD

[John Rogers]

How about Ford Pinto adjusters, they have a nice large foot to contact the valve stem. I have them on my 2.4l engine, no wear at all.

[Dave at Pelican Parts]

Do those fit in stock early or late style rocker arms? Are modifications required? The 73+ ones are larger in diameter, and won't fit in the 70-72 rocker arms.

Do these have "swivel feet", or are they just round-ended screws like the stock ones?

Evidently 911 swivel-foot adjusters fit into early rocker arms. But you have to trim the area where the adjuster goes, or shim the rocker stands to restore the geometry.

--DD

[John Rogers]

They fit "late" rockers and have swivel feet.

[mkinne]

Sorry...
I meant valve, not rocker arm. Guess I was picturing one of the other toys in the garage.

Matt

[Dave at Pelican Parts]

OK, first to make sure we've got the same picture in our heads: The adjuster is a screw with a rounded end. The rounded end pushes directly on the tip of the valve. (The tip is the part farthest away from the combustion chamber.) When the adjuster pushes on the valve, it pushes against the valve spring and opens the valve.

From there, I think it's not that hard to see how one piece of metal pushing on another piece of metal might wear one or both of them. The problem is probably worse in motors that have sat around for a long time, since there may be very little or no oil on the contact surfaces. The term is "galling", where friction can "rub away" some of the metal.

On the adjusters, this leaves pits and craters. On the valve tips, you will see small smooth depressions in a circle that is partway between the edge and the center. Or the tip can "mushroom" out.

In general, the adjuster and the valve tip have very similar "hardness" characteristics. If they didn't, then one of them would wear out pretty quickly. Some aftermarket SS valves seem to be softer than the stock adjusters, and they tend to "mushroom" pretty quickly.

Hope this helped to clear it up some.

--DD

[Bill Kohnke]

Yep My MSHP heads have worn down the first set of new adjusters in what I thought was too soft an adjust screw. So I ordered a second set from another source. Same problem 3000 miles and most of them are severly worn. I changed the height with shims and made sure that all are getting lubed (as poorly as this design is for lube of valves)
I'm getting ready to try hardened adjusting screws, God knows I not wearing down any of the valves themselves and Mark Stevens answering machine dosen't want to call me back.
Worn out in PA
Bill Kohnke

[Tom Notch]

The best adjusters I've found are the Berg 8mm ones that fit the early rockers. The large swivel foot is similar to the Porsche one (coincidence? I think not) and are very good against SS valve tips. I use the early rockers, Berg swivels, and the late bus spacers. Gives me a damn bullet proof assembly for a reasonable price. The Berg push rods are also a good investment for those that need a different length.

Hmmmm, MSHP doesn't answer their phone at all, unless they KNOW the voice. Won't answer their emails either. Seems like they are avoiding me and others, must be because they haven't sent me my parts that they said were shipped 5 months ago. Yes, I am an angry camper when I hear their name. Any other bad experiences with them on this list?



------------------

[Gary Ihas]

Mark Stephens area code has changed--861-822-5678

[Patrick]

They also went out of business. See the MSHP thread for details.

[neilca]

We got a set of heads done by MSHP last year and double checked the seat pressure. It was way too much (250 lbs) we removed a good .250 inches worth of valve shims to get to the 130 lb seat pressure we need to go to 8000 RPM. If you are running a street engine you need less spring pressure. If your heads were set up like ours you may wear out the adjusters prematurely and/or wipe out a cam.
Good luck
neil