Classic cars forum & vehicle restoration.

Minxy · Joined: 22 Sep 2010 Posts: 272 Location: West Northants

Good day all.
I have decided to invest in a automotive multi-meter that, among other things, will do dwell and RPM.
So has anyone got any recommendations and can anyone confirm if having a positive earth vehicle make any difference.
Thanking you in advance.
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Hillman minx convertible. Lanchester LD 10

MikeEdwards · Joined: 25 May 2011 Posts: 2467 Location: South Cheshire

I've got one somewhere that I've never used, if I remember I'll try to see if the instructions (if it has any) suggest any issues with positive earth.

ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire

have a look at this thread:

https://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?t=3361&postdays=0&postorder=asc&start=0&sid=dd31c0351586d716e7028fa98db10666

Dwell meters can be used on +&-ve polarity

Dave

Ray White · Joined: 02 Dec 2014 Posts: 6304 Location: Derby

Dave. Perhaps you could answer a question about dwell?

Which is more important, getting the dwell angle right or getting the points gap right?

I am not sure how you can be sure of getting both right.

Or am I being electrically illiterate?

MVPeters · Joined: 28 Aug 2008 Posts: 822 Location: Northern MA, USA

Ray
I'd say dwell is the most important. Jim Walker's explanation, the last post in the link UKDave provided, is a good one.
I've seen a US engine with an externally-adjustable points gap being tuned - it's a bit like adjusting the idle screw on a carb. to get the best running.
& then the ignition timing needs to be set & I, of course, would use a vacuum gauge for that!

Is Jim still around? We had several conversations about a Rolls that he was thinking of re-acquiring. Once owned by his family business, it was in a Museum on the west coast.
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

V8 Nutter · Joined: 27 Aug 2012 Posts: 587

I would say dwell is the most important. General Motors made the distributors with the window in the side where you can adjust the the dwell with the engine running, It's surprising the difference a couple of degrees error makes to the running, My dwell meter, an old American one I've had for about thirty years, will work on either polarity.

Ray White · Joined: 02 Dec 2014 Posts: 6304 Location: Derby

Thank you Gents. That was obviously a question worth asking.

alastairq · Joined: 14 Oct 2016 Posts: 1950 Location: East Yorkshire

MikeEdwards · Joined: 25 May 2011 Posts: 2467 Location: South Cheshire

Minxy · Joined: 22 Sep 2010 Posts: 272 Location: West Northants

alastairq · Joined: 14 Oct 2016 Posts: 1950 Location: East Yorkshire

ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire

measuring points gap was only ever a simple way of setting dwell, as it only required a cheap set of feeler gauges...these day electronic equipment is cheap in the 60's, 70's & 80's it was incredibly expensive .

Dave