Decided to change out my points to pertronix lobe sensing on my 67. On first startup timing was way advanced and knocking at idle. Ran good before no problems. Retarded timing using my dial back light to 46 deg total (vac adv, everything) and it backfired bad upon rev up. Went to 50 deg total and it was better but still not like before. That seems like a ton of timing to me and I wish I had checked it before the swap but I never thought it would advance just from the swap. The pertronix will only install in 1 spot so I know it's located right. The engine is pretty much a stock 326 ho w/ stock carb, distributor, intake. I've read for hours and need some direction. Everything I've read on Pontiacs says 46-48 is about max but it seems like this thing wants 52-54 degrees. Is it possible?

Did you pull the distributor out to do the job? I'm guessing you did. Those timing numbers are a bit off...A tooth or two off on the restab would be my guess.

Did not have to pull the distributor to swap in the pertronix. It was a quick swap.

U checking total with the vac advance disconnected?

It's 38 with vacuum disconnected and 50 connected

About 34-36 total without vac advance is what you usually hear is about right. 38 is prob ok

I have read that the 326 ho engine with 141 heads likes 41 degrees total without vacuum advance. Can anyone confirm this?

Sounds like it wasn’t such a quick swap after all.
My suggestion would be don’t just expect it to be right after dicking around with the dist. Start at the beginning and set it up like you just put a new dist in.

The closed chamber heads like several more degrees timing, than the later open chamber, so I would say that sounds correct. That's assuming of course stock compression, cam, 93 octane, and stock mechanical curve rate. IIRC, the 400/421/428 with closed chamber, like around 42-44 degrees total w/o vacuum. With the smaller bore of the 326, it would be a degree or two less.

Later open chamber heads (68+) are usually 34-38 degrees total.

If the car even starts after the Pertonix swap, with no further adjustment, I consider that a feat in itself. Having to readjust the timing seems like a given to me.

She's running better than ever now. The timing is now set at 42 degrees without vacuum. Thanks for the help guys and especially FirebirdMike for the specific knowledge on these HO engines!