MSD Distributor -O Rings on Lower Housing

[buns]

I posed this question on the MSD Forum a week ago and got no reply. So I thought I would try it here. I have an MSD Pro Billet distributor for a small block chev. Here is an excerpt from the installation manual.







I guess that must be a generic drawing because it sure doesn't look like a small block distributor hole. Pictured below.




I am wondering if maybe that drawing is of a Big Block, and also, why you would need to chamfer the bottom of the lower bore as the o-rings don't go down that far.

[buns]

Hmmmmm. I gave the tech guys at MSD 2 weeks to answer this. Still no reply. Now 2 weeks at Pro Touring. No reply. Maybe it's a stupid question?


And now for some comedy relief.

[68sixspeed]

just chamfer the upper bore. Also, On a lot of street motors I've left off the lower o-ring to send some extra oil down to the gear.

[Blown353]

I've never chamfered a block for an MSD distributor and never cut an o-ring by not doing so.

But like the poster above, I leave the o-ring off the bottom collar and use a triangular needle file to shape a .020" groove into the side of the distributor body to spray oil directly onto the distributor/cam gear-- position the groove directly over the gears once you have the distributor set for proper timing. This was strongly suggested to me by a couple of machinist friends as an "insurance policy" after I ate a distributor gear a couple years ago.

[buns]

Well, this thread doesn't seem to have capured the hearts of auto enthusiasts around the world, but I will post the reply I got from MSD.

If that is a stock oem block we do not recommend using the o-rings for the fact there is no chamfering done to the block in that area . Dropping the distributor in with the o-rings would only result in the o-rings being pinched off and ending up in the oil pan . After - market blocks typically have that area chamfered and need to have the o-rings placed on the distributor shaft for oiling purposes .