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How much have you safely advanced your 356's timing from the shop manual's recommended 6 degrees BTDC? We figure 6 degrees BTDC a general safe figure to encompass the range of gasoline quality, production variance engine-by-engine, drivers' habits.

I'm looking for performance and fuel economy but not interested in any cowboy nonsense. We know to advance it until it just starts to ping when you crowd the engine in high gear at 25 or 30 mph. But curious what the number of degrees worked out to; 7, 8, 9 BTDC ?

I know enough to keep my foot out of the carburetor, not pull excessive manifold pressure. Such cars were oft called "bankers' hot rods" in the day, with easy reserve of power.
For what it's worth, i've jettisoned over 100 lbs. from my car, and i'm slim, travel light.

Have whatever essentially straight through original type muffler John Kepich sells for our cars, so no more back pressure than when she left East Grand.

My head's of course iron, but 7.5:1 compression instead of the factory 6.85:1, if that makes a difference.

Rebushed distributor, weights lubed, ball race oiled. NOS manifold heat riser thermostat spring so no impedence there either. I got John Kepich to reproduce the rust-prone cover out of stainless steel if you need one.

Also, i've seen gaps for our 10mm spark plugs listed from .025 to .028. What's best for performance and fuel economy more than smooth idle?

Since my car's a '47 Super, i'm most interested in hearing
from '42 and up owners, but perhaps that distinction's academic.

Thanks for any insight.

I find that they run extremely well cranked up to 10 degrees or perhaps a bit more with no noticeable pinging or even harshness. The problem is that when hot they will not start. Its not that they kick back against the starter, it is as though there is no ignition at all. I end up putting them back to spec and sighing.

I'm eager to see responses to this post! (And assume most would apply to the 288 as well?)

Can anyone else provide any tips, tricks, or advise to this thread?

Personally, my goal for my car is to be a "driver". Although I've only taken it for a few trips around the block, I'd like to be reasonably comfortable operating it on the roads with today's vehicles. Any tips to increase its performance would be wonderfully helpful.

Although this may be asking for a departure from the service manual, I don't believe any fine-tuning information provided would be contrary to the nature of a Packard, "the banker's hotrod". Instead I feel it would only enhance the enjoy-ability of our cars.

Thoughts?

Try Ross' trick to advsnce timing. But add a manual distributor control like a motorcycle uses.

Might be able to add a second set of points with a switch trigger from start mode to running mode. Just depends on how much u waant to experiment.