Hi,
Going on inspecting the part for my B20, i was wondering how thick the cam thrust plate must be when new. Additionnally, how thinck is the washer that gos between the key and the front cam bearing. I'm wanting to reuse these but only if they are good (engine has low mileage)

Also, how is the orthodox method to take the key out of the camshaft?

Thanks, Sébastien

I often just flip the thrust plate over and use the unworn side. Because of the helical cut of the gears, the thrust direction is always rearward. I have never found a spacer ring to be undersize.
The location fore and aft of the cam in the block determines the lifter contact pattern on the lobe, so when it moves too far aft, it changes it for the worse - somewhat increased noise, and wear.
I also polish any used gear hub at the contact point to the thrust plate, and ensure that the oil groove is still acceptably deep.

The spacer ring should be .003" (.076mm) thicker than the plate. Basically, if there is any wear on the plate, it's out of tolerance.

If you drive the rear edge of the key down into the cam, the front of the key comes up, and can then be pried out relatively easily.

Many of the replacement fiber cams I've seen didn't really have a very smooth finish on the backside of the hub, which is odd because it is a bearing surfaces, and it rides against that thrust plate. I think the roughness of some replacement gears combined with a softer brass plate results in a lot of knocking at idle Volvos driving around.

The somewhat good news is that even though a worn thrust plate sounds pretty nasty (like a rod knock, only just at idle) it really won't do anything catastrophic for a very long while.
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I'm JohnMc, and I approved this message.

Séb,
I don't know the thickness of the thrust plate. Wear maks are normal and no reason not to re-use the plate, but when they start approaching about a milimeter in depth, in other words, when you can clearly feel a ridge when you run your finger over the wear marks, i'd get a new plate. Try to find a steel rather than a brass one. They last longer. The key can be tapped out with a flat punch. It's likely to get distorted. Sometimes you can dress it back to the right size by rubbing it on some fine sandpaper on a glass plate, but usually it's better to get a new key.
Bob S.

Bob!
You need to get a better grip on how big a millimeter is!
You can feel a ridge of 0.002" if it is relatively sharp.
That is 0.05mm. A millimeter of wear is MUCH too much to have
on a cam thrust plate.
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George Downs Bartlesville, Heart of the USA!

Yeah!! I'm with you on that George!

If you where an ant - a millimeter would be as high as a kerbe!!

(Seen from a metric part of the World..)



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/Soren