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MG MGA - Points gap and dwell angle

My MGA & MGB owners workshop manual (Brooklands Books) gives the points gap for the DM2, DM2.P4 and 25.D4 distributors as 24-26 thou. My MGB Workshop Manual also gives the dwell angle for the 25.D4 as 60 deg. I assume therefore that the dwell angles for the DM2 and DM2.P4 are also 60 deg?

Thinking about it more, it occurred to me that the dwell angle could be different in two distributor models with the same points gap. The maximum deflection of the points is determined by the 'size' of the lobe on the shaft. However, the profile of this lobe could be different on different models of distributor even though the maximum deflection is the same. This would result in different dwell angles for the same maximum points deflection. Is this logic correct?

What design feature determines the gap size and the dwell angle - presumably the charging characteristics of the coil?

Best regards
Richard

Richard Atkinson

Richard, Everything you will ever need to know about point gap and dwell can be found in the archives.

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2011020812414223533
Chuck Schaefer

Thank you Chuck - I missed that in the archives.
Richard Atkinson

Good grief - just spotted that I quoted the plug, instead of the points, gap - apologies. It should of course read 14-16 thou
Richard Atkinson

This thread was discussed on 13/08/2012

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This thread is from the archive. The Live MG MGA BBS is active now.