Reason Norton cams wear?

john robert bould said:

Oil mist and drips from the head! now thats a laugh :lol: when doe's all this happen :?: about 20 miles down the road :!: if all is well with the degign,,,why is there so many worn out in little miles :?: my Merc sprinter will do the clock round three times and still as no wear on the valve train...reason is on start up the cam gear is flushed with oil from oil jets from a huge supply...not some tear drop system that norton invented 60 years ago.

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Lubrication starts immediately on start up of engine. Every time I've stripped an engine that has been in recent use all the internals are coated in oil. Problem with the Mk3 cams was a faulty hardening process resulting in unequal hardness between the pairs of lobes. As far as I'm aware, any crankcase mounted camshaft engine depends on splash and oil running down the pushrod tunnels for lubrication - Norton didn't invent gravity :lol: Like I said before, it's very important to check when the PRV opens. What is yours set to out of interest?

john robert bould said:

Come on the pump is just about Rubbish, it carnt be any good if the pressure drops to zero at ftat out revs.

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This is one of the popular Norton myths, along with barreled superblend bearings and the machine tool plank. I've tested my bike at constant 5,000rpm, top gear, 22 deg C ambient temp, hot engine and 20w/50 oil. Oil pressure steady 55lb/sqin.

what happens a tick over?

Al-otment said:

john robert bould said:

Come on the pump is just about Rubbish, it carnt be any good if the pressure drops to zero at ftat out revs.

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This is one of the popular Norton myths, along with barreled superblend bearings and the machine tool plank. I've tested my bike at constant 5,000rpm, top gear, 22 deg C ambient temp, hot engine and 20w/50 oil. Oil pressure steady 55lb/sqin.

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This is why I like the cams designed for BSA radiused lifters. Wear problems are reduced. The lifter weighing 1/2 as much also makes a difference. Look how rounded the cam nose is for the same valve action..

Al-otment wrote;

I've tested my bike at constant 5,000rpm, top gear, 22 deg C ambient temp, hot engine and 20w/50 oil. Oil pressure steady 55lb/sqin

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More or less my findings, except on prolonged high speed cruising as the oil temp increases, mine can eventually drop down to just less than 10 psi per 1,000 revs

john robert bould said:

what happens a tick over?

Al-otment said:

john robert bould said:

Come on the pump is just about Rubbish, it carnt be any good if the pressure drops to zero at ftat out revs.

Click to expand...

This is one of the popular Norton myths, along with barreled superblend bearings and the machine tool plank. I've tested my bike at constant 5,000rpm, top gear, 22 deg C ambient temp, hot engine and 20w/50 oil. Oil pressure steady 55lb/sqin.

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Recorded pressure of 15lb/sqin at tickover, hot engine and oil. Flow rate is proportional to rpm. Pressure increases as rpm rises as clearance between big-end shells/journal and rockers/shafts is constant and restricts escaping oil. PRV opens to control max. pressure hot or cold.

This doesn't sound like a lubrication problem to me, it might be more a materials problem. If either component is soft, the wear can be unpredictable. If you want to cut a hard piece of anything, often it can be better achieved by using a soft wheel and losing a lot of material off it. If the followers are stellite tipped, I'd be doing a hardness test on the cams.

john robert bould said:

I still say the lube is weak , ]

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Not wishing to start another oil thread, but if the stellite hardness and cam hardness check out OK,
I'd be asking if all 4 followers look the same - and what sort of oil this engine has been running on. ?

Without ever having seen an example, this looks like how insufficient zinc ZDDP in the oil might look like ??
Assuming ALL the PO's / owners changed the oil regularly.
Time to cross that type of oil off our recommended list ???
Again, assuming it didn't do a gazillion miles without an oil change....