As per title, do new cam bearings generally need to be reamed once fitted? I only ask as I have one new set here that slide perfectly over the cam, and another one that doesn't which is from a different manufacturer but otherwise looks the same. I'm wondering if it is supposed to be reamed or if it is a dud.

There are two sorts on the market - 'non reamable' and 'reamable'. Apparently the non reamable can have sloppy tolerances and you run the risk of vibration moving the bearing. This happened in my engine I'm rebuilding - not with me but previous owner as when I pulled it down the centre bearing was 8mm out of the web and had fouled the push rod. The reamable one can be reamed to a tighter tolerance and you end up with a smoother running cam. A special reamer is used that lines all three up as well.

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Most cam bearings that you could buy now from Karcraft and elsewhere for years, are pre-finished.
I even had a NOS set in a BMC box that is pre-finished.
But you need to be real careful fitting them, or they distort- which is why I pay Graham Russell to fit mine, he has the proper gear.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

By proper gear do you mean the dollies?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

If that's what you call them, but I'd call them guide spigots and plates..
It's easy to bruise and deform them if you try and hit them in without them being guided.

I'd make some guides up if I had a bunch of bearings to do.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yep that paints a picture nicely. Thanks.

I've seen guys do it with three spigots (?) machined to fit the inner diameter of the individual bearing with a shoulder machined half way up. Then they were tapped in. Still easy to misalign I guess.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I would put a 16mm hole in all the spigots, then pull them in with a long piece of H/T threaded rod and nuts.. No BFH required.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

You are right, much more elegant.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.