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Dwell is Off, But Gap is Correct?

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H

hundredsixinsf

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The points on my '66 Midget are gapped correctly at .015", but my dwell is measuring around 25 degrees. How can this be? What could be the problem?

Thanks,
Steve
 
Steve - Your gap is a bit narrow. What the dwell meter is telling you is that you have a 65° dwell on a positive ground vehicle. I am assuming that your Midget is still positive ground and you are using a 3 wire dwell meter. If these assumptions are correct, the reading you get on the meter is the complement of the actual dwell angle (ie. 90° - 65° = 25°). This would put you 2° out of the spec - 60° plus or minus 3°.
Cheers,
 
/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif I would trust the dwell meter a lot more than a feeler gauge /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
Thanks Dave! Yes, it's still a positive ground car and I'm using a 3 wire dwell meter. Never knew that the reading on a positive ground car would be the complement of the actual dwell angle. Obviously a good thing to know when working on old original British cars!

--Steve
 
Haven't used a dwell meter in 10 years. If the gap is right it should run fine. If not, change out the condenser and see what happens.
 
Steve S. The dwell meter is a bit more accurate for most people than the feeler gauge method of setting the gap. for the person who is adept at measuring gaps with a feeler gauge, that is a quicker and perfectly acceptable method of setting the gap. I use both, roughing it in with a feeler gauge, then refining it with a dwell meter (after 40 years of working electronics, I am more comfortable with meters than feeler gauges). That said, I don't use either on the MGB since I converted to the Pertronix.
Cheers,
 
Hello all,

the feeler gauges are fine on new points, but once they have seen some service, the pip that forms means that the feeler gauges are inaccurate. Dwell meter for me every time. Useful to double check the voltage drop across the points also, if, like mine, it has a voltmeter function.

Alec
 
I guess I'm more of a nuts and bolts guy. Meters can read incorrectly, but a feeler gauge can't! If my points are old and pitted, I just replace them. A tiny bit of pitting isn't a problem. I've never found 1 thou variance in the points to be noticeable.

I'll admit I prefer screwdrivers to multimeters any day of the week. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
Steve! you just be plum old fashioned.---Keoke--- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif


-------Alec, You be spot on----- /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Steve! you just be plum old fashioned.[/QUOTE]
That's why I drive old cars. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Shoot if you can find one an old match book cover works great.
 
I'm with Steve.

First thing, it's a dwell meter. Next thing ya know there'll be whole FUEL MANAGEMENT systems, automagic transmissions and AIR CONDITIONERS in cars! sheesh.

WHAT'S th' world coming to!?! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif
 
I do have a volt meter, but it's analog. Had a digital one but I put 40,000 volts through it. I'd like to say it was on purpose.
 
My MAN!!! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif

"40K... no waiting." /bcforum/images/%%GRAEMLIN_URL%%/jester.gif
 
Actually I prefer them. they are much easier to read when the values are changing. This is the same reason I don't like electronic tachometers.
 
piman said:
....Dwell meter for me every time. Useful to double check the voltage drop across the points also, if, like mine, it has a voltmeter function....
Click to expand...

voltage drop across the points? Sounds like a valuable troubleshooting bit, but I've never heard that one before.

Could you elaborate? <bow> I am empty glass, master. Is it strictly a static test, or can you do it with the engine running? What kind of numbers do you look for?
 
Hello Eschneider,

the voltage drop across the points is a guide as to their condition, and yes it is a static test. In fact, it is also worth doing a check from the coil to earth with the points closed, it should be virtually zero, any thing much more than 0.4 volts shows that there is a problem, which can be worn points but also poor connection any where in the circuit, not forgetting the earth lead inside the distributor.

Alec
 
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