Symptoms of low dwell

[Jeff Rosansky CLC #28373]

What are the symptoms of low dwell?  I happen to have 2 dwell meters--Both of which are old and borrowed.  I was checking a couple of things today and noticed the dwell said 23-24....... Thought that was odd so I got the other one and it was just about 28........ I hooked both of them up at the same time and one reading 23ish and the other 27-28. 

Now I admit this is not an official reading as I was doing a quick check.  RPM was just over 600.  Timing was originally set at about 7.5 but now it is just over 10-- Advance plugged off but still idling faster than it should for the official check.  I know the RPM was too hi, but either way, one meter is off.

I am going to try to get another dwell meter and see which one it matches.  But I was just wondering what low dwell will 'sound' like.
Jeff

[Scot Minesinger]

Jeff,

Your other post where the car does not do as well as when it is warmed up sure sounds like the choke.  Open up the lid of the air cleaner and see if the position of the carb choke blades.

Once you get a good dwell meter, you will have this problem resolved.

[curly]

I never really noticed that low dwell readings had a noticable 'sound' effect, but in extreme cases of incorrect dwell, the engine ran terrible.

A rule of thumb that I learned many years ago is : The closer the points are together, the higher the dwell reading will be.
As points (rubbing block) wear, they will close up and the dwell will increase.  This will lead to a change in timing.  The rule is supposed to be a 1 degree change in dwell will lead to a 2 degree change in timing. (Distributor speed is 1/2 of crankshaft speed) I've seen change in dwell affect timing, but not the amount I was told.

Dwell will also affect the ignition coils ability to charge, a longer dwell allows the coil more time to 'recharge' but conversely, doesn't allow the magnetic field in the coil time to fully collapse. Not a problem at low rpm, but under load/high rpm high dwell can cause a misfire.

T Lewis

[Jeff Rosansky CLC #28373]

Sound was the wrong word, sorry.  What I meant to ask was how differently will the car run if the dwell is at 23 instead of 28?
Jeff