Points gap on the dizzy of a Mk1 1935 Ruby

[John Mason]

Hi all, Can anybody tell me what is the correct points gap for my 1935 Ruby. I have read somewhere differences between both 15 and 20 thousands on inch. I have run the engine on both these settings and it appears to run well on both. What is correct.

John Mason

[Chris KC]

That sounds a bit big to me John - I use 0.012 - 0.014"

[David Stepney]

12 to 14 thou is recommended for most Lucas distributors.

[Bill Dixon]

Yes 12 to 15thou,

[Chris KC]

By the way I think the practical meaning of this is that you set new points at 0.014" in the expectation that they will quickly 'bed' to 0.012", which is the correct gap. 

One thing to watch out for is that many distributors have over the years been re-built with 'available' parts. If you have ended up with a 'high lift' type cam (these are more square) the recommended gap is a bit bigger.

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Here we are, from Lucas technical training material:


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[Special Bits]

All the above advice is spot on.
However, in a pickle they will run on vastly differing points gaps. During the Lands end trial this year the points on the Ulsteroid closed up to the point that I had to stop and do something with them. This was at around 4am! We were already running late so I whipped the cap off, reset them by eye and torch light, and off we went, running perfectly again. I havent checked what the gap is, but Id imagine closer to 20 thou than 10.

Stuart

[bob46320]

0.002" being half a fine hair width !!  I doubt any of us get down to this accuracy as feeler gauges are the usual measuring instrument and the accuracy of feeler gauges leaves something to be desired.  I think that before we worry about the last 0.002" tolerance, we should look at the "slop" in the top distributer bearing and the fit between the cam and the rotor shaft.  The points gap at rest is different to the points gap when running in most cases, and a more accurate way of setting points would be with a dwell meter (which of course most of us don't have !!).

[Hedd_Jones]

i use the thumbnail of my left hand. Seems to work fine for bosch or lucas