saggy Posted June 9, 2014 Report Share Posted June 9, 2014 Morning Everyone, I don't seem to beable to find anything much on the usual websites, and what there is seems to vary between 60, 55, 54, 34 and even 13 (degrees) Yes, 13 degs on one website for a well known classic car magazine! I'm guessing for a standard 4 cylinder it should be one the higher figures, but can anyone tell me from any factory/workshop manual/bible they might have, what the correct dwell should be please? Also I gather that some people are changing the 4 deg BTC to nearer 8 deg BTC because of lead free fuel. So should the dwell be any different now for the same reason, and if so, more of less? Thanks, Saggy Quote Link to post Share on other sites
Peter Cobbold Posted June 9, 2014 Report Share Posted June 9, 2014 If the points gap is set standard the dwell angle is set by the cam. Peter Quote Link to post Share on other sites
bob-menhennett Posted June 9, 2014 Report Share Posted June 9, 2014 (edited) At the time I struggled to find it in the Triumph reference books. A four cylinder engine should be 54 degrees ( 60 % ). 54 divided by 90 ( the 360 degrees divided by 4 ).... multiplied by 100 = 60 % I found it in a 1987 book produced by Gunson Limited ...The Auto Expert, Understanding the Ignition System. I'd regard it as start point.Slightly loosen the distributer clamp, just enough to be able to rotate the dizzy by hand and experiment ! You're aiming for the smoothest tick over. If you put the knurled micro adjuster in the central position you can make small adjustments later to complete the fine tuning. Bob Edited June 9, 2014 by bob-menhennett Quote Link to post Share on other sites
Ian Vincent Posted June 9, 2014 Report Share Posted June 9, 2014 If the points gap is set standard the dwell angle is set by the cam. Peter I use the dwell angle as an accurate way of setting the points gap, and yes the manual that came with my dwell angle checking meter which I bought about 30 years ago says 54 deg for 4 cylinder motors. Rgds Ian Quote Link to post Share on other sites
peejay4A Posted June 9, 2014 Report Share Posted June 9, 2014 (edited) Don't you measure dwell angle with the engine running? I had a dwell meter once and that was how it worked. If that's still true I can't see that it's particularly easy to do as you have to measure dwell, shut down, cap off adjust points, repeat etc. Edited June 9, 2014 by peejay4A Quote Link to post Share on other sites
Guest ntc Posted June 9, 2014 Report Share Posted June 9, 2014 Pete You do not need the engine running mate. Quote Link to post Share on other sites
peejay4A Posted June 9, 2014 Report Share Posted June 9, 2014 How's it done? It was a pain with my dwell meter so I binned it. Quote Link to post Share on other sites
Guest ntc Posted June 9, 2014 Report Share Posted June 9, 2014 http://www.gunson.co.uk/items/pdf/Technical/G4089_Testtune_New-6wire_Instructions.pdf Quote Link to post Share on other sites
peejay4A Posted June 9, 2014 Report Share Posted June 9, 2014 Page 15 says start the engine. Now I'm confused. Quote Link to post Share on other sites
Guest ntc Posted June 9, 2014 Report Share Posted June 9, 2014 You calibrate a dwell meter before you begin Quote Link to post Share on other sites
peejay4A Posted June 9, 2014 Report Share Posted June 9, 2014 (edited) Couldn't see that in the manual and page 15 still says run the engine to measure dwell, like my old one. Sorry if I'm being obtuse. Edit. I suppose you could turn the motor over on the starter. Or perhaps use the meter across the points and use a cam timing disc. I think I'll stick to feelers. Edited June 9, 2014 by peejay4A Quote Link to post Share on other sites
saggy Posted June 10, 2014 Author Report Share Posted June 10, 2014 Just returning to this topic to be polite to thank you all for your help. As always, much appreciated. Best regards, Saggy Quote Link to post Share on other sites
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