I am trying to restore a 1961 Navigator. The crankcases are now split. The camshafts have some play in the bushes on the timing side of about 4 thousand on an inch with a bit of ovality. On the primary side it’s onstage 2 thou.
Whilst the bushes have plenty of meat on them I am worried that if I don’t do something some thing about I will have a noisy engine and difficulties with tapper clearance.
Am I being overly cautious? Any advice would be welcome.
Camshaft Bearing clearance
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Long shot but....
Long shot but I purchased some camshaft bushes for my Jubilee from Russel Motors a couple of years ago. It took some perseverance to get them to look in their warehouse but they came up with the goods eventually. The bushes cost only about £18; very reasonable.
They only deal with customers face to face or on the 'phone.
Dennis
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Put Lightweight Camshaft bushes on the spares request list?
I can't find lightweight camshaft bushes in the NOC shop so is it worth putting in a request for them to be made and stocked in the shop?
They are quite simple items. I know they rarely fail but when you need them, you need them!
I think the part numbers are 20771 and 20772. I got those numbers from a 1959 parts list for Jubilee but they may be correct for all lightweights.
Dennis
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Camshaft bushes
The part nubers are 20772 (drive side) 22925 for the timing side.
I wi get put in a wish ist for the bushes. Thanks
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Source of bushes
I tried Russell motors as suggested and they have all I want. They cleaned out the spares from Norton factory many years ago. Fantastic tip Dennis
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Hi Robert,
Looking at the "Twin Cylinder Manual" for Norton's, Published by Norton/AMC around 1965, the following is quoted.
Lightweight twins:-
Camshaft bearing diameter 0.9365ins/0.9360ins.
Bore of camshaft bushes 0.9383ins/0.9378ins.
Upper/lower limits.
Based on this you could check to see if the camshaft bearing journals are worn, or the bushes, or both. It looks like the design clearance was between 0.0013ins and 0.0023ins.
Bad luck having worn bushes as they are very robust and seldom wear. In addition to the possible effects you list, add poor control of points cam and a hard life for the oil seal behind the advance/retard.
It's easy for dirt, gasket, or gasket sealant to fall down the camshaft bearing feeds and block the little hole above the bearing. Examine your crankcase, cylinder barrels and cylinder heads and you will be able to work out this oil feed from the rocker overflow.
In your position I would replace only the timing end bearings. You may have to get an engineering company to make you some up. In old money the bore of the bush is 15/16ins, but I don't think oilite bushes of that size are available now.
The manual I quote is a useful purchase.
Good luck
Peter Holland