Topic: point ignition swap out to Pamco electronic-advice please

[el pachuco]

if the old coils are working well why go to the expense of new ones that may have to run a resister to use and will draw too many amps for the old charging circuit to keep up with I personally believe highly in the hondaman ignition you only have to set the pionts once and you don't need to run any more condensers and you have the added bonus of being able to switch back on the road if you ever have a failure and I have heard that pamco does not respond well to warranty issues

Can you be more specific? Is there a particular person that has complained of poor warranty service? If so, then please ask that person to post his complaint here so we can all see it.

Also, if you use the new coils that come with the kit you do not have to use resistors and the coils do not use more current than the stock coils, so, where did you get that information from?

Stock coils 4.5 Ohm with 180 degree dwell = 12.5/4.5 * 50% = 1.38 Amps
17-6903 coils 2.8 Ohms with 120 degree dwell = 11.5/2.8 * 33% = 1.35 Amps

I use 11.5 volts for the PAMCO because there is a 1 volt drop across the transistor.

When calculating the current for a coil, you have to take into consideration the effect of the dwell angle because the coil is only on for that period. So, in the case of points with a 180 degree dwell angle the coil is only on for 180/360 = 50% of the time. Using the dwell angle on time gives you the average current flow to the coil which is the effective current flow as far as the charging system and battery is concerned.

During the time that the coil is on and drawing current, the stock coil draws 12.5/4.5 = 2.7 Amps. The 17-6903 coil draws 11.5/2.8 = 4.1 Amps so the magnetic field in the 17-6903 coil will be almost twice the magnetic field of the stock coil. However, the battery and charging system will only be affected by the average current, so you end up with a better spark with no impact on the charging system.

The PAMCO uses a 120 degree dwell angle so the coil is only on for 120/360 = 33% of the time. Some will jump in here and say that the shorter dwell angle of the PAMCO means that the coil output will not be as good as a 180 degree dwell but you have to take into consideration the fact that an electronic ignition system produces a faster rise time because it does not use a condenser. Test have shown that an electronic ignition system, not just the PAMCO will produce up to 50% higher voltage at the plugs than a points system driving the same coil, so you can reduce the dwell angle without sacrificing the spark voltage and end up with a more efficient ignition system and cooler running coils. This is true for any electronic ignition system, not just the PAMCO.


CB750 Points
PAMCO and stock coil
PAMCO 3/4" gap
Note: The video frame rate will sometimes miss a visible spark, but the sound of the spark is consistent.

Conclusion: 1. Points with a 180 degree dwell, 1/2 inch spark gap.
                   2. PAMCO with 120 degree dwell, 3/4" spark gap
                   3. PAMCO produces a 50% greater spark with the same coil.
                   4. PAMCO uses the same current for a 50% increase in spark.
                   5. The 120 degree dwell of the PAMCO results in a cooler running coil because the coil is on for only 33% of the time vs 50% of the time for points.

What's the importance of a cooler running coil?

1. Longer life for the coil.
2. Less increase in primary resistance due to the increase in resistance caused by temperature.

Additional notes:

Using a points booster with a high performance coil that has a lower primary resistance will result in a higher average current because the points booster still uses the stock points cam that has a 180 degree dwell.

Points booster with a 180 degree dwell and a 2.8 Ohm coil:

11.5/2.8 * 50% = 2.08 Amps

I use 11.5 for the voltage because a points booster circuit also uses a transistor to drive the coil.

Even more notes:

The actual dwell angle for the CB750 is 190 degrees which results in a 190/360 = 52% on time or duty cycle so the conclusions above would be even more favorable for an electronic ignition compared to a points system with a 190 degree dwell.

Excellent post with great detail.
 I think it is well worth quoting and reviving this thread. It appears that Pamcopete has left the building. Too bad, but I can't say that I blame him.

I wonder at what RPM his points vs. the Pamco ignition test was running at. Not that it makes much difference but the closer to idle speed, the more effective the product. My'75, with worn points, has a pretty erratic idle after the engine has reached full operating temperature. I think I know why, now.

I'm ordering my Pamco ignition in the morning.

[Scott S]

 Pete is still a member and was active yesterday. Not sure why that profile shows up as "guest", but he's still around.

http://forums.sohc4.net/index.php?action=profile;u=33864

[el pachuco]

Pete is still a member and was active yesterday. Not sure why that profile shows up as "guest", but he's still around.

Good to hear that. Thanks.

[PeWe]

You must adjust the points with a dwell meter connected to achieve same gap on both points. The idle will be very stable if carbs are OK.

[el pachuco]

You must adjust the points with a dwell meter connected to achieve same gap on both points. The idle will be very stable if carbs are OK.

For how long?
I have very limited experience with points. They were being phased out as I started riding and driving.
How often should the points be checked and adjusted to keep them performing as they should?

[Deltarider]

How often should the points be checked and adjusted to keep them performing as they should?

Checked per maintenance scedule but don't be surprised if you don't need to adjust them in 20.000 kms+. Pewe is right, a dwell meter is an useful instrument and it's my feeling that if people used it more, there wouldn't be so much 'synching' going on.
For those of you that, like me, prefer a dwellmeter over a feeler gauge, here is a tip.
Years ago I have attached two ‘blind’ extra wires to my coils (12V-) both with a female connector at their end. Once you've set your timing correctly, these wires allow quick diagnoses later on. If you are satisfied with the timing, write down the dwell for future reference. Almost all changes in timing originate at the contactbreakers. When the dwell changes, so does the timing. When you suspect the timing is off, before opening the ignition cover you can now simply connect the dwellmeter to either extra lead 1&4 or 2&3 and verify if dwellangle is still the same or has changed. It’s important ofcourse that those connectors are well shielded to avoid ground. That's why I choose mine to be female. Mine are accessible close to the ignition key (under the tank).
I have had these wires attached for years now. What I like is that I can check real quick without even having to remove the ignitioncover.

Another remark.
If you've done it correctly, in future you can adjust the timing by just resetting the contactbreakers gap and you can leave the platescrews untouched. That's how Honda dealers used to do it.
In this forum there is much messing with timing plates (why? because it is in a book?)

[el pachuco]

When dwell (gap?) has changed, I'm assuming it is because of wear on the breaker's surface material. What method do you use to resurface them, or do you replace them at the first significant sign of wear?

[Deltarider]

I have changed very few contactbreakers. The sets that are on now, have been there for the last 55.000 kms, be it that most of that distance they have switched my homebuilt transistor ignition module, so didn't have much amps to deal with. Never noticed any wear on the little fiber blocks. Just keep that little felt lubed, is all what it takes. At the beginning of the season I move a contactbreaker file up and down between the points (only once) and that's it. Fresh owners of electronic ignitions always emphasise the 'set and forget' convenience where in my experience there isn't that much adjusting if you use the right parts.