11-09-2020, 09:27 AM
(10-09-2020, 08:59 PM)Ian Williams Wrote: There is something seriously amiss with a lightweight special that is not capable of more then 45mph I don't believe the gearing is going to be it. It is very hard to answer the questions without seeing the car in the flesh and knowing what has been done to it, which Duncan appears not to know either, first stop would be ignition timing and mixture. You mentioned the exhaust system what is on the car, is it seriously restrictive which if so may be the problem? The manifold is, as on all sevens, dreadful but that should not stop it from achieving a far better top speed than quoted.Leightweight special? The weight makes no different at all to the eventual top speed on a level road.
Top speed depends on the engine power at the revs concerned, and the wind resistance.
Remember the 45mph is an accurate figure, not a speedo reading which would likely be 50mph.
The mk2 Ruby was given in reports from 1936 as a stopwatch top speed of 53. A saloon will be less air resistance due to a much smoother shape so in perfect condition a special might be a top speed of 49. The 45 is less, but not a lot less.
The exhaust on the special is a standard front pipe, but with a kink at one point, then a small silencer of unknown construction, and a tailpipe about a foot long.
What top speed would you expect Ian?