Rocker arm scoring

Both my 750 and 850 had damaged rocker arms, presumably from bits of metal circulating with the oil. The scoring varies in severity. I replaced all of the doubtful ones and now have a full set of junk rocker arms as souvenirs.

I was wondering though, how much scoring can they have and still be useable? Basically I replace them if I can see or feel any damage at all. But can they still be used with just "light" scoring? Or is it possible to have them bored out and sleeved like people do with valve guides? I hate to throw them away if they can be salvaged.

Debby

Debby,

Anything can be salvaged. It just depends on your resources! :lol:

These arms are scored in the bore? Was the corresponding spindle damaged as well?

It is unusual you were two for two on this. I don't remember having a smilar issue and I have torn down some pretty abused motors. I'm not doubting yours were scored, but curious as to the cause. Lack of lube? Swarf from a destroyed bearing?

Ron L said:

These arms are scored in the bore? Was the corresponding spindle damaged as well?

It is unusual you were two for two on this. I don't remember having a smilar issue and I have torn down some pretty abused motors. I'm not doubting yours were scored, but curious as to the cause. Lack of lube? Swarf from a destroyed bearing?

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yes and yes, Ron.

In both cases it definitely looks like shrapnel that went through the engine, quite likely from a failed bearing. In both cases the oil pump scavenge gears were damaged as well. The 850's pickup screen did not appear to catch everything. There was also scoring on the big end shells, although on the 850 the crank journals were ok. The 750's crank had to be reground.

No more ebay Commandos for me! I just don't seem to have good luck with them :?

Looks like Andover does not manufacture new rocker arms, but Norvil does offer new ones for sale. Don't know where they come from, but they have "new stock" listed for sale on their website. Norvil's do not include the ball end so I guess you would have to take it from the old arm.

Debby

A circumferential score or two in the rocker arm bore should not cause any problems, so long as the remaining bore is within specifications. Notably, many shell-type main bearings have a score or groove to serve as an oil channel.

debby said:

Looks like Andover does not manufacture new rocker arms, but Norvil does offer new ones for sale. Don't know where they come from, but they have "new stock" listed for sale on their website.

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The rocker arms are listed but with a "Please call
+44 (0)14 8868 6816 for additional information on this part." note.

So I would assume that they could just be out of (or low on) stock at present?

debby said:

Norvil's do not include the ball end so I guess you would have to take it from the old arm.

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The rocker arm ball ends (066978) are listed and priced at £4.45GBP ea. http://www.nortonmotors.de/ANIL/Norton% ... 03&Part=34

Old Brits can supply rocker arm ball ends. They are not in the parts list but a call or email to Ella is all it takes.

Del