You learn from what's killing you.

July 7, 2010

Need some tech help.

Ok, i have that BluArc distributor in my panhead and im going to put new points, etc, in it.
the one in the middle is the one that was in it. the two others are the 2 different replacement ones I have gotten for it. The contact to the cap is obviously different.

my question is, what exactly is the difference going to be, timing wise and how it runs.
i think it determines dwell, but as i have never actually fucked with distributors in the car world, other than just replacing parts.
so, anyone want to explain???
thanx
D

9 comments:

LUCKY said...

Dave I work in the auto parts world, the cap won't know the difrence long as A: the rotor shaft is the same in all three B: the highth of rotor is the same. Long as the rotor is physical the same the timing will be groovy!

Heroin- respectthepanda.com said...

I've always been under the impression that with the wider distribution area, you're just giving the arc more choices from which to jump since the spark timing is determined by rotor shaft positon no the width of the distribution point. So, narrow or fat, It shouldn't make a difference as long as it's quality is fair and the shaft was timed right to begin with but I'm just a drunk so...

drsprocket said...

Dave, I know you know these are rotors and not points. Rotors have cast in keys that and can only go one way. These are all constructed differently but all do the same thing. Your points on the other hand have to be timed (opening and closing)and that's where dwell comes in. You knew that right? Just jerking us.

drsprocket said...

Dave, Part II If you didn't pull your distributor the position of the rotor will be where it should be which is dialed in on number one cylinder. Your points should fire 7/16" before top dead center (on a v-twin) . Use a timing light if it's an automobile to set the degrees on your dampner as recommended by the manufacturer or cam maker (turn the distributor). this is a test,right? I know you know this?

yumyumchoppers said...

all the rotor does is transfer spark from the coil to the plugs. I'm pretty sure you set the dwell with the points settings.

pat said...

you could maybe take the one on the left and cut the ends off so it is the same width as the one you were running. just make sure its the same amount from the centerline as the original.

Chopperdave said...

yes dwell is determined from how long points are open. its never really been a factor in the vtwin world, well it is but never something anyone i knew measured, as long as your gap is right and the points cam is in good shape and the contact patch is good the dwell shouldnt change. is just weird to me that the contact from rotor to cap is different on each rotor, thats all.

it makes me curious as to why the rotor contacts are all different. thats all really.

rowdyj883 said...

The area of the rotor should have no difference once everything is properly adjusted. The spark will jump from the same relative position until the points begin to wear, distributor components wear, or carbon builds up. Points were meant to be set up with a gap as a rough start, and dwell is to be set as a fine tuning to complete the tune up process. Dwell is a measurement of degrees of cam rotation that the points remain open. People rarely fixate on the setting because the significance is arguable. Timing is a funny game because you're aiming at a moving target to begin with and points wear- changing the already tricky timing. You should be able to find an electronic kit that replaces the points to improve timing accuracy and reliability while the rest of the distributor remains unchanged. This is pretty general info though, and I'm not very knowledgeable about differences between single fire and dual fire distributor components. I also think some Pans distributors had opposite rotation... motorcycles are just like women.... fun as shit to ride, but you'll never figure 'em out!

RichieG said...

Dave, I run a blu-arc in my flattie and wondered that also. I trimed one down to duplicate the original rotor and it worked fine.
I haven't rode it in a while and was wondering what type of points they take. I thought I had it written down somewhere. I seem to recall Opel Cadet or GT also they are picky about coils. A small one came with it I think 3 ohms? Any help would be appreciated. They are great ignitions when dialed in.