340 Initial timing questions

midnight340 said

Mopowers, thanks for that link.

I have read that 50 total is not too much for a lower compression motor as it's working too hard at a steady run down the highway.
And I'll have to double check the vac. adv. #. I said 16, but I think MSD book says a max of 10 is available. It's been a while since I set up the distributor.

Click to expand...

Right, and here's why! You never ever include vacuum advance when talking about timing. Ever. You always just let it "end up" wherever it is. There are adjustable vacuum advance cans, but that's not for the purpose of total timing. Total timing is initial, plus mechanical. PERIOD. It appears that you get that.

The reason the vacuum advance can "doesn't matter" is because it will never be in the picture while accelerating under a load. When the throttle is opened, vacuum drops off so the vacuum advance does not work then. It's sole purpose is to clean up the combustion at cruise and part throttle. That's "about it".

In fact......it says right in the Mopar Performance engine book that it's not uncommon to see 60* timing with the vacuum can attached at part throttle cruise. Perfectly normal.

Sounds to me like you got yours just about right. I don't think I'd mess with a thing.