Ignition timing

Per the 1959 Maintenance Manual;

Before TDC fully advanced 32 Degrees.

Before TDC fully retarded 10 Degrees.

Hi, I followed the book to the letter, and my Navigator started, but didn't run so good. As with most engines of this age, nothing is as precise as we might like. I would suggest you start with textbook specifiaction and see how it runs.

Any bike should run, so long as it is getting fuel and a spark on the compression stroke, but peak performance is, nearly always, dependent upon the bike in question. So tinker away, with small adjustements to the timing, until you get the best performance that you can, and then tinker with carb until you get likewise. (of course make sure your valve timing and clearances are correct first). This is the fun of old bike ownership. Enjoy the tinkering.

I know people will disagaree but, in my opinion, obsessing about the specification, to the n'th degree, is not the best way to achieve good running. These machines have been around a while!Paul

Paul's advice makes good sense and that's a good looking bike to prove it. I like the straight handlebars - it was so typical sporting Norton way back in the fifties/sixties..

When the lightweight Norton apppeared in 1959 five star leaded petrol (101 octane) was still readily available so these old engines were actually made to use much higher octane than is now available. The Navigator engine used a few degrees less advance than the Jubilee so around 24/26 degrees fully advanced will probably be about right on modern fuel.

I bought my MGB (secondhand) in in April 1969- 46 years ago- and I remember having to retard it's timing way back in the seventies when 5 star ceased to be available because it would pink horribly on 4 star. Then I had to retard it again when 4 star ceased. But it is still running well on modern fuel (with ethanol) although performance is down from the original spec. I quote this as a good example as the MGB still has it's original engine with original twin SU carburettors and the original distributor it left BMC factory with in 1965. The valve seats were changed though as the original seats couldn't cope with unleaded.

The Norton valve seats seem to cope with unleaded fuel OK but using some octane booster in the fuel would be an advantage. Retarding timing too much will result in overheating and over advancing will cause pinking - so a bit of experimenting is needed to get the best result.

Patrick.