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I currently have the head off my TR3a to address a problem with suspected (and now confirmed) coil binding on the exhaust valves.  I have dealt with that but whilst I had the head off, I removed the cam followers to check that there wasn't any damage to either the cam or the followers.  Fortunately there wasn't any damage, (the degree of coil binding was very marginal) but looking at the pattern on the followers it is clear that some of them haven't been rotating or have only been moving through about 10 degrees.  There doesn't seem to be any pattern in that it isn't restricted to either the exhaust or the inlet valves, both types are affected but only about half of them.  The rest show a nice circular polished area extending across the central area of the follower to within a couple of mm of the edge.

Does anyone out there have any experience of this happening to them?

The followers were new at the same time as I installed a new camshaft and were supplied by Newmans.  They are not phosphated or drilled and a quick check with a micrometer shows no difference in diameter, they are all 23.8mm dia over their full height.

My initial reaction is to very slightly reduce the diameter of the ones that haven't been rotating with some 1200 wet & dry.  Does anyone have any better ideas?

Rgds Ian

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Nope, although deduction says there is a difference either in the camshaft lobe centre grinding positioning ( maybe offset some thousanths more than others) which causes less circular “encouragement” of the followers, or the block camshaft holes are marginally tighter on some holes.

You could measure the offending follower positions in the block but I’m sure they will be within a thou, or polish the cam followers trying to lose some tenths of thous and ease their turning. So I think I would do what you are considering.

Mick Richards

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