Setting points

[asneddon]

I recently bought a rev counter off ebay (at last!), and to set the revs correctly I also bought a nice new automotive multi-meter that has an RPM readout (my old one didn't). As this new multimeter has a dwell angle setting as well I thought I may as well check my settings.

Turns out it was set to 40Degrees! I adjusted it up to the 60 Degrees I get from both here and here, but I ended up with a gap of about 35-40thou, rather than the 16 to 20 I was expecting. I also got quite a lot of pinking. If I set the points above about 65 degrees I can't get the car to start.

I've since wound it back to 50 degrees dwell according to my meter, which is about 25 thou from my feeler guages. I've now noticed quite a bit of 'chuffing' which I didnt get prior. This is about a week after I set the dwell though.

so, question is: Is my new multi-meter crap and lying to me, or do I have something wrong with my distributor?

[asneddon]

Actually, now that I've written that, I think I might have been stupid, and hooked the dwell angle up wrong for dwell (I left it the same as the hook up for the rev counter). The larger the points gap, the higher the reported dwell angle. This isnt right is it?

If dwell is the degrees of rotation the points are closed, thus allowing the coil to charge, then surely the smaller the gap, the longer the points are closed, and the higher the dwell angle.

I guess the 40 degrees I had was actually 90-40 = 50 degrees. When I set it to 60 degrees I probably actually had it at 30.

Damn, tune up in the car park at lunch time I think!

[capt jack]

The bigger the dwell, the closer the gap, and vice-versa......

Jack

[VolvoFan]

I've mentioned this before, but didn't get a response: when I set the dwell angle on my 1800 E distributor to the correct spec., 59 - 65 degrees, the points gap is 0.012" - well below the Volvo recommended setting of 0.016 - 0.020 This is something that I can't find a reason for, as there is no appreciable wear in the distributor. But as the engine runs very well, without any timing problems, it is something I have come to accept over the past 20 years that I've owned & serviced my car.

If I set the points gap to the recommended size, the engine races on idle and is too far advanced, so I always set the dwell angle when servicing.

Hope this is of interest.

[asneddon]

I think this comes down to my new meter being crap. I had it set right (red to -ve on coil, black to earth). With points set to 18 thou I get 42degrees, but car runs great.

I dont have a timing gun on this side of the planet, so dont know my timing. I've set it by driving and adjusting till it 'just' doesnt pink. Possibly I have both set wrong, with the end result being good.