Dwell reading question

[Jrsdart]

folks I need your help once again.This time it's about my dwell.The cam lobes on my distributer are not worn, its a 1969 coronet with 19k miles it has a 383 2bbl.The manual states to adjust points to 14-19 and the dwell should be 30-35.The issue is when I set the points at 14 I'm getting a dwell reading of about 26.Should I lower the point gap even smaller to get the correct dwell reading?What may be causing this to happen?Thank you once again for all of your help.

 

[Pops1967GTX]

The distributor rotates, then points open, Make sure the shaft has rotated until the points are fully open on the lobe to set the points gap... Try another lobe to check for wear too see if adjustment changes...

You must check your timing after you adjust gap, must sure its correct.

Nice article ...
Dave's Place - The Lost Art of Maintaining a Mopar Distributor​

 

[Jrsdart]

Thank you pops, I tried a few different lobes and got the same results. I loosened the distributer to make sure I had it exactly at the top of the lobes. I will have to bring the point gap down to 10 to get the dwell within 30-35. You think that's what should be done? Usually I set the points at 17 and the dwell is at 30-35. But not this time. Any other suggestions will be appreciated.

 

[Pops1967GTX]

If you loosen the distributor did you recheck timing?


Adjust the dwell while cranking the engine, with the cap & rotor removed connect dwell meter & chick the starter with the key on. You can adjust your points while cranking & watching the dwell meter.

Don't keep key on too long...

 

[Jrsdart]

Thanks,pops,I will give that a try,I was checking it with the engine running,maybe that was the problem.ill do that then get back to you.thank you again.

 

[lewtot184]

dwell should be 27-32 for single points; 37-42 for dual points.

 

[Yatzee]

folks I need your help once again.This time it's about my dwell.The cam lobes on my distributer are not worn, its a 1969 coronet with 19k miles it has a 383 2bbl.The manual states to adjust points to 14-19 and the dwell should be 30-35.The issue is when I set the points at 14 I'm getting a dwell reading of about 26.Should I lower the point gap even smaller to get the correct dwell reading?What may be causing this to happen?Thank you once again for all of your help.

I doubt very much that you can really find a quality set of points these days. The best I ever had in the past was BlueStreak brand. Hall those buggers out and under magnification see if the contacts are precisely parallel. If not, toss them. See how much spring pressure they have by manually moving the arm away and letting it go. If the contacts do not line up perfect, and tend to be on the heel of the contacts they're trash. If the shaft for the distributor has lateral play, you'll never get ideal gap or dwell. This is why so many people have opted for electronic style pickups as opposed to points. China will be glad you stuck with points cause there ain't nobody here that makes them.

 

[mopar 3 B]

Quality points have not been available for 30 years. Surprised you can still buy them.

 

[Pops1967GTX]

Quality points have not been available for 30 years. Surprised you can still buy them.

I'm still old school & running ignition points in mY GTX...I still Have a few sets Of dual & Single Points. If you adjust your points properly they will last....

 

[PRND21]

Do you have access to another dwell meter to compare readings? Sounds to me like your meter could be showing a false reading. Bad battery? Set on 8 cyl? If I remember right, .017 gap should give you about 32 degrees dwell.

 

[mopar 3 B]

Only way I would consider using points would be to adjust them on a distributor machine another obsolete piece of equipment.
Point being point gap is set at dead stop them there are 8 lobes on the V8 even if you average the gap on all 8 lobes what you going to use for final gap? An average.
Dwell is checked a idle and can become very inconsistent as rpms build do to point bounce.
I was encountering this when good points were obtainable and test machines were available and that was in the 70s.

 

[lewtot184]

i haven't messed with points in a long time but IIRC the tighter the gap the higher the dwell angle. i always shot for the wider gap so the points would last longer.

 

[miller]

Dwell is the angle of degrees, the points stay open...
.017-.018 has always worked for me. But, will admit using a feeler gauge is something, not all do the same. Probably why it's called 'feeler'...lol!

Do you have wiper pads on the points rubbing block, or finger (as some call it)? That's the only way the dist cam gets lubed.

 

[Cornpatch MO]

If you loosen the distributor did you recheck timing?


Adjust the dwell while cranking the engine, with the cap & rotor removed connect dwell meter & chick the starter with the key on. You can adjust your points while cranking & watching the dwell meter.

Don't keep key on too long...

Thanks Pops, I never thought of doing that.. sure would make setting with a dwell meter a lot easier..............................MO

 

[Cornpatch MO]

dwell should be 27-32 for single points; 37-42 for dual points.

What if you put a little piece of cardboard between one set of points at a time? then what would the dwell be on the fireing set of points?...........................MO

 

[miller]

If you adjust gap at .017, 'on' the top of the lobe, for each set of points, you'll be good to go...and, the dwell will fall right into range. You can use the advance plate, to move point block onto the cam lobe, many times.
Years ago, used to fool with checking dwell (sure, good to know), but if the gaps are right, that's all that's needed. Go ahead and check dwell...you'll get it figured out. Only thing I've ever used was dual point. Slightly old school.

 

[RJRENTON]

I concur.....but realize that there are 2 different sets of variables. Distributor contact openings are measured in a decimal number like 0.014 inches to 0.020 inches, measured with a feeler gauge set at the high point of the distributor cam opening. The other variable is degrees dwell as in 28 to 32 degrees (of rotation of the distributor cam lobe from points open to points closed).
Dwell setting is a personal thing vs correct thing. I usually set single points to 26-28 dwell ( which results in the points being OPEN slightly greater) My reasoning is it allows the rubbing block to be able to wear slightly, yet still allowing to points to be in tolerance. The same thoughts apply to dual point distributors. Set slightly on the high side to allow for wear.
One important consideration is: set the points first then set the static timing (@ idle with vacuum advance DISCONNECTED). That way, the timing will still be in tolerance.
Years sgo, i was able to purchase 20 sets of NOS mopar points and condensers for my Prestolite dual point distributor in my GTX at a big mopar car show. In the prestolite dual point distributor, one set of points MAKES the coil charging circuit and the other set of points BREAKS the coil charging circuit creating the spark. The reason for the 2 sets of points is longer charging time for the coil to develop the spark energy....presumably for high speed operation.
The settings do not have to be dead nuts....just get close. For my dual point distributor, i set both points at 0.014" with distributor out of the car. This results in a running Dwell of approximately 38 degrees. This is what works for me.
Bob Renton

 

[Cornpatch MO]

If you adjust gap at .017, 'on' the top of the lobe, for each set of points, you'll be good to go...and, the dwell will fall right into range. You can use the advance plate, to move point block onto the cam lobe, many times.
Years ago, used to fool with checking dwell (sure, good to know), but if the gaps are right, that's all that's needed. Go ahead and check dwell...you'll get it figured out. Only thing I've ever used was dual point. Slightly old school.

I know how to set dual points, I just want to know what a dwell meter should read...specific , not in range..........................MO

 

[miller]

The manual states to adjust points to 14-19 and the dwell should be 30-35.The issue is when I set the points at 14 I'm getting a dwell reading of about 26.Should I lower the point gap even smaller to get the correct dwell reading?

Okay...look at your own numbers. Gap at .014, getting dwell of 26. Manual tells you to gap at .014 - .019, and dwell between 30-35. That should tell you your gap is too small.
But, know that (probably already do) dwell is...the 'time', in degrees, that the points are open. That recommended dwell number is simply giving you a number to go for, for the best spark to the plugs.
Been years since I fooled with a dwell meter. Even have one, but batteries for it haven't been made for 25 years. So, only talking from past experience, and knowing that the rubbing block on the point set, can wear down...and make the gap smaller. Right?
So, putting gap on the high side, like .017, maybe .018, normally put dwell on the high side of the range.
Getting a certain dwell number dialed in, is easy, on one set of points...not so easy on dual points. Unless, you can set both point gaps exactly the same. But, the dwell falls into the needed range, to work right, and last awhile.
In my case, I know a gap of .017, puts dwell where is should be. Be better to get .0175.

 

[383man]

Dwell is the angle of degrees, the points stay open...
.017-.018 has always worked for me. But, will admit using a feeler gauge is something, not all do the same. Probably why it's called 'feeler'...lol!

Do you have wiper pads on the points rubbing block, or finger (as some call it)? That's the only way the dist cam gets lubed.

Actually dwell is the time in degrees that the points are closed.
I have to think your dwell meter may be a tad off. 26 degrees dwell will be fine but if they are good points and are not pitted then I would set them with a feeler gauge at .017 and leave them at that. Ron