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A can of wormsi know ,but in the bit more oomph department,is the Hemmings PW3 the same as the the Emery 3S ? give or take some chilled cast iron . Looking to make those convoy overtaking manoeuvres just a bit more torquey, a bit morezippy !
Alec, they are most defini…
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Alec, they are most definitely not the same! The 'Hemmings' PW3; never heard it called that before, it is the Peter Williams 3, to give it's full title; was, as the name suggests, developed by Peter Williams to give the racing Norton's an edge; a very good cam, by most accounts.
The 'Emery' 3S is a Norton cam, not an Emery one (!); the cam which Norton developed from the 2S for racing purposes. It is the Production Racer cam. For road use the standard cam is still a very good choice, but if you want to play, go for the PW3, not the 3S, which you are likely to find tiresome for road use, assuming you manage to set it up properly; don't bother!
Out of interest, is it for a 750 or 850? You may need to carry out other modifications in order to get the best out of either of them, or even to show a benefit. You will have to ensure your valve springs do not get coil-bound. If so, you will have to machine thevalve stems or spring seats to restore the correct spring length when fully open. Also, you will no doubt have to open up the camshaft tunnels to give clearance, likewise the tappet tunnels may need relieving to prevent contact. Check carefully for piston to valve clearance..... As you say, a can of worms.
Do a search of this site, you will find lots of info and comment on cams.