Correct use of a dwell meter...

Dangermouse · Post by **Dangermouse** » Thu Sep 14, 2006 2:28 pm

Hi folks,

Hope this question isn't tooo trivial but...

I tried setting my dwell angle the other day and appear to have fried my meter; is this likely? The meter was the digital automotive multimeter type, not exactly el cheapo but not terribly flash either. I connected the red terminal to the #1, negative terminal on the (6 volt) coil, the same terminal that the condenser wire attaches to, and grounded it to one of the bolts that attaches the coil to the fan housing. I started the engine up and turned on the meter, nothing, dead, blank screen (it appeared to have been working beforehand).

So could I have fried it? The really high voltage only shoots through the centre coil post to centre of distributor wire, right? And its ok to measure dwell with the engine running (as opposed to just cranking over with the coil wire removed)?

I brought the meter back to the shop as it wasn't terribly old and declared it a POS; they replaced it without any fuss. But I don't want to destroy a second one without confirming that I at least have the procedure right first. Was it just coincidence that it failed at that time? Or did I do something completely wrong...

The Noof · Post by **The Noof** » Thu Sep 14, 2006 2:50 pm

You had it hooked up correctly.Meter just malfunctioned.

Post by **Marc** » Thu Sep 14, 2006 6:44 pm

This is an externally-powered dwell meter? Is it supposed to work on 6V?

Dangermouse · Post by **Dangermouse** » Thu Sep 14, 2006 6:52 pm

No no, internally powered by a 9V battery...

Like this one...

Wondering now if it wasn't just coincidental, however unlikely???

Post by **Marc** » Thu Sep 14, 2006 6:57 pm

And the leads are plugged into the correct terminals at the meter?

Does the ohmmeter function correctly? If not (and the 9V battery is OK) the meter is probably toast.

Dangermouse · Post by **Dangermouse** » Thu Sep 14, 2006 7:05 pm

And the leads are plugged into the correct terminals at the meter?

Yup, quite sure of that.

Does the ohmmeter function correctly?

nothing funtions, no readout at all, He's dead Jim, kaput. I had put a new battery in just to confirm that that wasn't the problem either. Shop confirmed that it wasn't a battery problem but didn't seem too concerned beyond that.

So at least they replaced it with a new one, but I prefer not to repeat the experiment....

Dangermouse · Post by **Dangermouse** » Sun Sep 17, 2006 4:18 pm

So, reassured that I'm not going about it completely wrong, I tried out the replacement meter over the weekend and it just won't measure dwell. It turns on ok but as soon as I hook it up, it behaves very erratically, screen comes on and goes off again, flashes nonsense and stabilises at a dwell reading for a couple of seconds before blanking again. Other functions, including RPM, work fine and meter appears otherwise AOK.

Could it be my 6 volt coil that's confusing it?

weird

davidsigouin · Post by **davidsigouin** » Fri Oct 06, 2006 4:52 am

What cyl setting is your meter set on? 3,45,6,8?? Are your leads plugged into the 2 right side sockets on the meter as seen in the previous post? Inductive pickup not plugged in

Dangermouse · Post by **Dangermouse** » Tue Oct 10, 2006 6:45 pm

Meter was set for 4 cylinders and leads were most certainly plugged into the right holes. The inductive pickup pictured with the meter is for use in measuring RPM; for dwell measurements there were two leads with alligator clips which I used. It really looks like the meter is just calibrated to read 12 volt signals and couldn't pick up the 6 volt signal.

Anyway, I acquired an old, analogue-type dwell meter and hooked that up and it seemed to function fine so I guess at this stage I'm prepared to resign myself to the fact that 6 volt systems bring specific problems. I still wouldn't be tempted to change it over though, I like it running 6 volts.

BUT - in order to get a dwell reading of approx. 50 degrees (25 degrees on an 8-cylinder scale), I had to gap my points to .035 rather than .016; should I be concerned about this and what does it say about the condition of my distributor?

After I did this the engine wasn't running too well and I returned the point gap to .016 (but I have a nagging suspicion that that might be because I timed the engine on cylinder #3 instead of #1 'cos I forgot to check the position of the rotor

. I'll have to go back and repeat the exercise).

davidsigouin · Post by **davidsigouin** » Fri Oct 13, 2006 6:16 pm

Definitely retime on cyl 1 as 3 should be retarded on that engine. If you time on 3 all timing will be out