CB360: how to set dwell?

tweakedlogic

tweakedlogic

Been Around the Block
I've been having trouble with my spark lately. I remembered I have a Cornwell multi meter that can check dwell. Checking dwell is the only way to make sure that both points are set identically, I just never worried with it because she ran fine.

The way I remember setting dwell on my old truck was to take off the distributor and have some one crank the engine while I make adjustments. The problem with that with that method is I don't have an electric starter, I have to kick it to start. I'm pretty sure the energy going through the points with the engine running would fry the meter.

So what do I do? I don't think I can turn the crank smooth enough by hand, which may skew the test.
 
You don't set dwell on a motorcycle. (generally)

Dwell is determined by point gap. The method for setting the points on this bike is that you set point gap to 14 thou, adjust timing on left cylinder by rotating the point plate. Then you adjust timing of the right cylinder by slightly tweaking the point gap for the right cylinder. Identical dwell between the cylinders is irrelevant.
 
Re: Re: CB360: how to set dwell?

AlphaDogChoppers said:
You don't set dwell on a motorcycle. (generally)

Dwell is determined by point gap. The method for setting the points on this bike is that you set point gap to 14 thou, adjust timing on left cylinder by rotating the point plate. Then you adjust timing of the right cylinder by slightly tweaking the point gap for the right cylinder. Identical dwell between the cylinders is irrelevant.
Click to expand...

You can do this with a timing light or a gun - there's a good explanation in your manual.
 
Also some really good YouTube videos.

I threw my old dwell meter in the trash. Timing light, too, although, maybe I should have kept that.
 
Dwell is the angular "time" the points are closed before they open and create a spark. On a V8 car for instance, the dwell has a relatively short dwell angle available because there are 8 lobes on the point cam. A dwell meter helps you maximize the dwell time, and since all eight cylinders are affected at once, it is a good method of getting a strong spark.

On the dual coil twins, with t points, the dwell is determined mostly by the shape of the cam, and is optimized by the manufacturer. Since there is only one lobe on the point cam, the dwell can be pretty long, compared to a car.

The biggest problem on a car is getting the dwell long enough to get a well saturated magnetic field in the coil. On the twins, there is plenty of time relatively. In addition, you do not want to power the coil for an excessively long time, as it will use a lot of current, which can burn points, overheat coils.

So a dwell meter is not needed, and pretty useless for a single lobe point cam. The dwell is long enough that the small differences in the dwell caused by point gap, is not significant.

The best thing is to follow ADC's advice. In addition, if you have one, a timing light will allow more precise timing between the 2 cylinders and also allow you to get it on the the timing mark. Save the Dwell meter for the 1965 Chevy Impala...
 
Right, I know. I've set the gap and timing. But using a dwell meter is the only way to be certain that both points have the exact same gap. I am only human with a long flimsy bit of steel, sticking it between two more bits of metal, trying to gauge drag on the first bit of metal. See, not very precise. Test one side with the meter then test the other, and set it to match.

I found this earlier while searching. He agrees with me. http://www.motorcycleproject.com/motorcycle/text/sohcign.html
 
On dual point twin cylinders, having an identical gap is not necessary. The dwell is long enough that the small difference dwell is irrelevant. Having the gap identical offers no performance advantage. It also would require the points to be identical and that they wear identically. Ain't gonna happen.

Having the 2 cylinders fire at the correct time (same dwell does not guarantee this) is better for performance than any dwell reading obtainable.

For all practical purpose, you have 2 single cylinder engines. The ignition system is separate for each cylinder.

Get the timing right and the dwell will take care of itself.


Sent from planet Earth using mysterious electronic devices and Tapatalk
 
tweakedlogic said:
But using a dwell meter is the only way to be certain that both points have the exact same gap.
Click to expand...

Lose your obsession with this concept. It is wrong. You adjust the timing of the second cylinder by tweaking the point gap within a couple thou either way.

tweakedlogic said:
I found this earlier while searching. He agrees with me. http://www.motorcycleproject.com/motorcycle/text/sohcign.html
Click to expand...

He is full of shit.
 
From that link:

"Don't lubricate the advancer mechanism. Its hardened steel design completely eliminates the need for lubrication that was the hallmark (and downfall) of its pushrod British twin counterpart."

Nice.
 
The followers on the rocker arms for my 360 are hardened steel and they didn't take too kindly to my elimination of their lubricant...
 
Rich Ard said:
From that link:

"Don't lubricate the advancer mechanism. Its hardened steel design completely eliminates the need for lubrication that was the hallmark (and downfall) of its pushrod British twin counterpart."

Nice.
Click to expand...

Honda says light grease on the cam. Proper lube is important, but no lube is insane.
 
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