I have just fitted a new oil pump to my '56 19S. With the fibre washer placed over the outlet spigot I have offered up the outer timing cover and measured the gap to the inner cover at 0.030". In the PL Garratt guide the required gap to ensure compression of the washer is stated as 1/64" (0.015" near enough).
I think this subject may have already been discussed on this forum, possibly in relation to fitting the conical rubber from a Twin to a Single. Fairly sure the advice then was not to use the conical seal as the extra thickness could result in overstressing the case when tightening up the screws, and possible risk of cracking the case.
With that in mind is a 0.030" gap too large? Should I be looking for a thinner fibre (or other material) washer for the pump outlet seal?
Cheers, Ian McD
More reading...
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I always rely on Edgar Franks
as he was actually there and responsible for much of the detailed design. Haycraft is merely a rehash of his book but useful as a standby.
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PL Garratt was there too....
So why the discrepancy? Could Garratt's 1/64" be the minimum gap and Frank's 1/32" the maximum? It would seem sensible to quote upper & lower tolerances for this.
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I have to confess
I've never heard of PL Garratt which is why I didn't mention him. Who is / was he?
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Repair Manager, Norton Motors LTD
Is how PL Garratt is described on the front cover of the Norton guide. The title is "Norton - A Practical Guide covering all standard models from 1948". It was published by C Arthur Pearson and was part of a Motorcycle Maintenance and Repair Series along the same lines as Pitman's Book of the.... First published 1949, my copy is the Fifth edition from 1962. I don't know if there are any later editions.
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Thanks for that
I don't have the Pearson book and hadn't heard of Garratt. I accept he may have had more "hands on" experience than Edgar Franks - a bit like John Hudson in later days.
I'll look out for a copy of the book - but it'll have to be cheap!
<edit> Interestingly, a google search suggests that Franks was the author. https://www.worldcat.org/title/norton-motor-cycles-a-practical-guide-covering-all-models-from-1932/oclc/9607442#borrow
</edit>
<edit 2> and when I look at my Franks copies (1949 and 1952), that is the title that appears on it - and it's published by Pearson! No mention of Garratt. Maybe he came along later.</edit>
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Just found my own answer! Franks, Haycraft, and the '56 maintenance manual all quote 1/32" for the timing case gap so 30 thou should be fine.
Ian McD