Someone explain to me about Dwell angle.

[Jon O.]

I have an old Dwell/Tachometer. I know it has to do with checking the points, but what does it mean, and what can I do with it? Thanks.

 

[Turboomni]

Do you have points?

 

[Jon O.]

Do you have points?

Yes

 

[Turboomni]

Dwell angle is the amount of time (measured in degrees of distributor cam rotation) that the contactpoints remain closed. Initial point gap determinesdwell angle.

 

[Turboomni]

Why dwell is important. Inductive ignition systems store their energy in a magnetic field - correct dwell allows this field to reach its maximum strength within the design limits of the coil.



Dwell angle is the amount of time, measured as degrees of rotation, that contact breakers close in a distributor. Unless dwell angle is accurate, ignition timing won't be accurate. The period, measured in degree of cam rotation, during which the contact points remain closed is called the dwell angle.

 

[Jon O.]

Why dwell is important. Inductive ignition systems store their energy in a magnetic field - correct dwell allows this field to reach its maximum strength within the design limits of the coil.

So if my dwell meter reads about 57 degrees, isn't that too much?

 

[Turboomni]

Yes. You sure you have your dwell meter set on 8 cylinder if there is such a switch or reading the correct scale on the meter>??

 

[Jon O.]

Yes. You sure you have your dwell meter set on 8 cylinder if there is such a switch or reading the correct scale on the meter>??

Yes, but im also not sure how accurate it is. It is probably more than 40 years old. What problems would there be with too much dwell?

 

[Turboomni]

I can't imagine if dwell was that high it would run well ,maybe not at all. How is the car running?
You could get a new tach ,dwell meter to be sure. They are cheap.

 

[Jon O.]

I can't imagine if dwell was that high it would run well ,maybe not at all. How is the car running?

It runs ok, thats why I haven't screwed around with it too much. But if the engine isn't still hot, it has real trouble starting. But I think that is a carburetor issue.

 

[Turboomni]

I got this to check against my very old one. They are cheap.

 

[moper]

Dwell is more critical than point gap. I like a dwell around 28* with most factory or stock replacement aftermarket coils. Set dwell, then set timing, then look at the carb.

 

[Jon O.]

View attachment 190820
I got this to check against my very old one. They are cheap.

Ok ill probably get a new one, and then check back on here. Thanks for your help.

 

[Turboomni]

Yes my dwell is 28/29 degrees. Factory manual says 32 or so,but then again the manual says base timing on my 440 should be 4* btdc....lol.

If your going to keep points order up a set and condensor and buy a good set of feeler guages. Points work great when set up correctly. I find points are the first thing people point at [no pun intended] as to why their engine isn't running well which could be true but maybe not. Instead they would rather yank it for an electronic ignition but if the points weren't the problem ,they still have a problem.
My 440 wasn't at it's best when I got the car but I didn't know that as I never owned a BB before. I also hadn't messed with points since the 1970"s. Guys would say get rid of those points and get real power etc. The setup from the previous owner's mechanic went by the book but many things were wrong. Long story short the 440 now starts right up even hot ,has much more torque and idles great and I get 15 mpg instead of 11 mpg cruising around.

 

[Big_John]

Since your reading of 58 degrees is ~double what the reading should be, I would say you are in the 4 cylinder range of your meter. Either you are reading it wrong, or there's a switch somewhere etc. Could be the meter is just bad too.

 

[polara71]

Dwell angle is the amount of time (measured in degrees of distributor cam rotation) that the contactpoints remain closed. Initial point gap determinesdwell angle.

Dwell is more critical than point gap. I like a dwell around 28* with most factory or stock replacement aftermarket coils. Set dwell, then set timing, then look at the carb.

Yumping Yimminy, I just learned how to say jelly and they changed it to jam

 

[Fratzog]

Good info on this thread.