So Nera but so far
Ben Pierce is planning to use his 1926 Neracar on the next Cannonball Run across the United States. He’s pretty confident about the 350cc Blackburne engine, but asks if I know a source for reproduction valve springs.
Personally, I’d say anything will do that fits, so long as it’s not too strong, which would lead to stress on the cam and followers.
Strong valve springs are needed for high-revving engines because they have to deal with greater load – any component has far greater weight behind it at speed – and sharper timing to fill the cylinders, putting the valves closer to the rising piston. Both demand accuracy, which is where mechanical operation (desmodromics), fourvalve heads, multi cylinders (smaller valves mean less less inertia) or simply stronger springs come into it.
But an engine like Ben’s Blackburne is low-revving and, being side-valve, in no danger of valve/piston interface. So the most likely problem, especially on the Cannonball, is the springs softening with heat and possibly valve breakage. Breakage is avoided by ensuring tappet settings are maintained – big gaps cause valves to snap shut. A Tufnol insulating washer between spring and seat will help with heat, but springs are easily changed anyway. I’d look for a car valve spring the right size that allows you to open the valve reasonably easily by hand, buy several and change them daily.
Sounds like a great trip and I hope Ben will let us know how he gets on...
Mike Porter has been working on a Fastback Norton Commando he bought without papers. Having reached a stage where costly parts are needed, he asks whether it’s actually worth it and will he be able to tax it once it’s ready?
Two big questions: while you accept that a new bike is worth significantly less than you paid as soon as you ride it away, we expect classics to appreciate in value. ‘Investment’ is an unpopular word suggesting financiers treating our bikes like stocks and shares, but realistically few classics do more than keep pace with inflation. They are only an investment because poor interest rates make them literally ‘better than money in the bank’; but if that justifies buying a classic to your family or spending money on restoration, is that a bad thing?
Classic values could rise or fall in future. The best advice is the art dealer’s answer – buy it because you love it, not to make money. But in Mike’s case, he’s concerned about whether he’ll be legally able to ride it once it’s finished.
Provided the bike is substantially standard, there should be no problem getting it re-registered with the DVLA (well, once the current crisis has subsided – they must have a huge backlog right now). There’s a checklist of major components that are expected to be standard – frame, forks, wheels, etc – although they needn’t be the originals or ‘matching numbers’, just of the same type and age. The DVLA have limited knowledge or interest in classic vehicles, so you need to make your claim as easy as possible to process. It’s well worth getting help and evidence of authenticity from a recognised source (eg the Vintage MCC or Norton Owners Club) confirming the age of the bike. You don’t generally have to be a club member, but expect to pay a fee.
Because 40 plus year old vehicles are tax exempt, dating refers to the most recent component, so if you fit a Fireblade front end and wheels to your Bantam it will be registered as 1990s, with no tax exemption.