My damper marks were off so I sent it to Damper Doctor and it's a one day service plus shipping time. I agree with Talkwrench about pinging, if you don't hear any, it starts easy, and idles nice 37-39 is fine.
On our 2 racing engines with great fuel, and 14-1 comp there was no gain over 37 so that's where We run both of them. One an inline and the other a bent 8.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Like many people who replied, my anecdotal observations are pretty much aligned with what others have found. A stock Y will take a lot of advance and like it. At least, by '64 the Truck-only Y-block was considerably detuned with a low compression ratio.

On the plus side, this also means it will run tolerably well on mule-piss and corn-squeezins or low octane fuel. When you get it tuned well to take advantage of the timing, a bad tank of gas is immediately noticeable. Probably one of those 30 per cent batches of fuel that "accidentally" made into your local retailer. Now Etoh isn't "bad fuel" per se, but jetting, compression, and advance curves are different.

The key to tuning, and this took me a long time to figure out, is throw the vacuum advance away for a little while. Forget, for the moment, it even exists. Then as mentioned, make sure TDC is marked accurately, the damper is still damping, and find out what YOUR engine likes, with good fuel and the distributor innards are clean and tight and moving smoothly. 34°, 36° 38° maybe more, depending on altitude &c, ignition health. It takes some test drives, what you're doing is the poor man's Distributor Curving without a Sun tester. With Ford distributors it is Not Very Friendly to make internal adjustments, because the breaker plate must be removed. Ordinarily Lighter springs must be used, and check to see that the total mechanical advance is not excessive.

One question I haven't seen answered, Why do Dampers have a "0" Mark and numbers out to 40° BTDC , but also a -10° ATDC? Why would somebody time an engine to ATDC??? Maybe it was a smog thing on some engines? So why does my PowerBond damper have this mark? (Damn good dampers btw)

Vacuum Advance Figure should be kept in mind IF You are leaving the Vacuum Advance hooked up. Don't forget at Cruising Speed when Engine Vacuum is High the Vacuum Advance will come back into Play. Depending on how much Advance is available You could easily end up with 50 Advance which is too much. Limiting the amount of Advance is a good Idea.

  

I recently had a chance to go through the distributor in my TBird.  I am running a stock 1957 single point distributor out of a 40,000 mile station wagon with a Pertronix unit and coil. It seemed to be working OK, but the idle was inconsistent.  Full advance didn't come in until about 4,500 rpm.  What I found was a bunch of dirt and gum around the centrifugal advance mechanism.  The ball bearings holding the advance plate were also dirty and hanging up. I didn't find any excessive wear.    I cleaned everything out with carb cleaner and soaked the bearing plate in solvent until it was totally free.  At the same time, I replaced the big spring in the centrifugal advance with a small spring.  I am now running two small springs and everything is free. My vacuum advance canister is new.

Before I took my distributor apart, I did not connect the vacuum advance line.  I always time the engine at 36 degrees full advance and lock it down.   When test driving the cleaned up working distributor, I found the car responded better with the vacuum advance line connected. It's a much smoother engine now.  I have an Isky cam in my motor.  It's not radical, but it thumps noticeably.  Now that everything is working, the car idles at 800 rpm and stays there.  Drive ability is much better.  When you floor it, it takes off like a rocket and revs to 5,500 rpm without drama.   Life is good. 

Too little advance isn't good either. 50° BTDC under certain specific conditions is very much typical for V8

In '64 the initial timing spec was 6° BTDC, but another 5° additional to that to improve performance or economy was acceptable.

Then the internal distributor mechanisms (reluctor, or slot) for 292 available were either 13° or 18° distributor degrees (e.g. 26° or 36° at the crank.) With a 13 slot there's 37° right there, at least at full throttle

The vacuum advance in '64 was rated at 6° and 1/2 (or 13°at the crank.) That's 50° right there.

Plenty of ignition advance under lightly loaded conditions is where fuel mileage can safely be improved, mostly at steady level highway cruise.

This is why vacuum advance was invented, there isn't nearly enough ignition timing advance available for best running at steady cruising speeds in high gear when using weights and springs alone, the engine will run too hot when the timing is retarded (and will run too hot when overly advanced, or too lean a fuel mixture)

It's worth taking the time to experiment a little bit and find a combination of initial timing, weights, springs, slot, tension, vac advance, etc etc that works for the particular application. It's important to keep in mind performance tuning is different than stock OEM tuning, or tuning for mileage or range.

I have that same Type Distributor in mine. The '57 with the Ball Bearing Breaker Plate. I lucked out and found a NOS Breaker Plate on Ebay. The One in Mine had developed Flat Spots in the Balls from moving only a small amount over the Years. One other Adjustment I made was to ad a couple of Shims between the Collar and Body to get the Vertical Play within Specs. There is a preferred Spec for that Measurement in the Shop Manual. .022-.030. You mentioned You changed the Heavy Spring to lighter Spring. You can also adjust Centrifugal Advance by working through the Small Hole in Breaker Plate to bend the Posts that the Springs hook onto.That can also be done on the later 2 Piece Breaker Plates. Ford had a Tool for that but I think One could be improvised. You can fine tune the Advance if You are so inclined. Too bad the old Sun Machines are gone.You could really Tune a Distributor on One of those. Where did they all go to when they were taken out of Service.? There was a mention in one of the other Posts regarding a lack of Timing Marks after about 10 BTDC. Mr. Gasket sells a Timing Tape #1594  for Small Block Ford that is pretty Accurate when used on a Y Block. Off a little bit because of the Difference in Diameter but can still give a better Idea of Timing than not having Marks at all past 10 BTDC. .


  

I called all around trying to find someone with a distributor machine in my area.  No luck.  It seems they all went to the big engine shop in the sky.  I found the same thing looking for a wheel balance machine that could spin balance my wheels and tires on the car.  The new computerized wheel balancers aren't worth a damn. 

I don't know where "all those Sun machines went?" ,but I do know where went....my basement! It sits comfortably there and is a cool toy to have. MIKE

Mike, still lovin his 57 t'bird after 53 years!

I guess they are a Collectors Item now. I remember We had One in Auto Shop in High School. Wish I had learned a little more about it then. Nice to have it now.

  

Here's a funny story.  Back in the sixties a friend and I went to a local speed shop.  They had some guy there talking about distributor curves.  My friend was a wise guy with a very sarcastic humor.  He also had one of the fastest cars at our local drag strip.  The man giving the talk said "For $10 I can give anyone in this room a 10th on the drag strip!"   My buddy said in a loud voice "I'll take $100s worth!"   I still laugh about that.