Question about mechanical advance

[DJCarbine]

I recently rebuilt my distributor in my 66 C-code 289, and noticed that my advance arms were a little different from what I have usually seen. Instead of the more common 10L and 15L arms, I saw that mine were 13L and 18L, allowing for more advance than usual. I had only seen and heard of the 10L and 15L arms untill now.

Is this of any significance? An uncommon find?


Well, I thought it was cool

 

[rbohm]

you have a somewhat rare piece, but not that rare. at 10 degrees initial timing, you would get 36 or 46 degrees total timing depending on which groove you use. i would use the 13L opening for the street.