what's for the arrow on distributor reluctor ?

[Nacho-RT74]

what you read!!! I have mounted on both pin locations and didn't notice diff... I guess is to fit the pin on that location depending of dist rotation, but REALLY I can't tell the difference.

My question is because I got a new reluctor without the arrow mark. Of course I can tell what pin provision should have the arrow, because I have the other reluctor, but IF YOU DON'T ?

[John_Kunkel]

Correct, the arrow marks the direction of rotation, the small block distributor rotates clockwise while the big block rotates counterclockwise.

You might not notice a difference in running but the spark inside the cap knows the difference; it has to jump a larger gap if the reluctor is installed in the wrong position.

[Nacho-RT74]

sorry, didn't get why... I mean.. I understand what you said, but I can't see mentally why is that...

[resq302]

Ahhhh...... John, I think you might have just shed some light onto my problem I have been having with my charger backfiring since I had the distributor rebuilt.  I usually get a lean backfire through the carb.  I will have to pop the cap off and see where the reluctor is in reference to the pin. 

If this is the case and my reluctor pin is in the wrong area, would going from cruise to WOT or idle to WOT and the incorrect indexing of the reluctor cause a lean backfire?

[John_Kunkel]

As the centrifugal advance advances the position of the reluctor in relation to the magnetic pickup it causes the spark to occur sooner in relation to the crank position and it also also advances the rotor in relation to the metal post in the cap that the spark jumps to. (rotor phasing)

If the reluctor is positioned improperly in relation to the rotor position when the spark occurs (incorrect rotor phasing), the spark might have to jump such a wide gap that the spark intensity at the plug is reduced and there is a possibility of "crossfiring" wherein the spark jumps to two posts at the same time causing a misfire. Also, jumping a wider gap can increase the ionization within the cap which also causes misfire.

Even with all the correct parts installed correctly there can be incorrect rotor phasing; I believe it's been discussed here before. (Do a google search of distributor rotor phasing)

[Nacho-RT74]

interesting... was some hard to imagine, but sounds interesting!

[idahogrumpy]

Take an old distributer cap and cut a hole out of top center large enough to see the rotor. Then out the cap on and rotate the distributer  the correct way and watch the rotor tip as the magnetic switch points line up. Then change the reluctor pin into the other slot and check it again. You will see the difference   Kyle.