Quick timing advice needed...

[bobioknight]

1957 Yblock 312 (rebuilt 8 years ago), Holley 4 barrel, Fordomatic, premium fuel, zink additive, lead additive.

The shop manual states

At idle set initial timing to 6* at 500 rpm in neutral.
Vacuum approx 19 in.

I have been reading that most people are running their timing at around 12*, is there any reason why I should advance the timing greater than what the manual specs, it seems to run well as is. Any advice would be great, either way. Thanks.

[LOWRIDER]

They just run better set at 12*. More vacuum at idle, smoother idle, more power and better fuel mileage. If you encounter spark knock at 12* just keep backing it down a couple degrees at a time until the spark knock ceases. That's how we timed them at the dealer for years up to the point where engines came out without the ability to adjust timing.

[Johnnydidd]

Mine runs great at 4 degrees BTD, it was set on 10, but runs great at 4??????????

[miker98038]

It's not uncommon for the damper ring to slip, so unless you find TDC mechanically and check the timing marker, who knows.

[dmsfrr]

Originally Posted by LOWRIDER

They just run better set at 12*. More vacuum at idle, smoother idle, more power and better fuel mileage. If you encounter spark knock at 12* just keep backing it down a couple degrees at a time until the spark knock ceases. That's how we timed them at the dealer for years up to the point where engines came out without the ability to adjust timing.

I agree ^^^ although at higher altitudes you can't advance quite so much.

Originally Posted by miker98038

It's not uncommon for the damper ring to slip, so unless you find TDC mechanically and check the timing marker, who knows.

Yes, but it depends on where the timing marks are located. If they are on the damper ring and the rubber is slipping it might be time to consider having the pulley rebuilt. http://www.damperdoctor.com/

On a '55/'57 T-Bird the timing marks are on the fixed metal rear edge of the pulley, not the weight ring.
Although they still have the same problem of the ring slipping/coming loose/causing damage. In any case, the timing marks can be hard to see. It doesn't hurt to clean and mark them clearly.

And yes, the engine support bracket in the photo below is wrong for the T-Bird it's in.
.

[willowbilly3]

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And always remember, the factory specs on any old car was for the gas they had then which bears little resemblance to what we have now so factory specs are just a rough guideline. Some engines are a lot more forgiving than others, even on the curb idle. I had an early 300 six that only ran correct set at 3-4 degrees, not 2 and not 5. And if I set the curb idle even 50 rpms over the factory spec, it would run on after I shut it off. When it was tuned right, it did .17 % CO and under 100 ppm on HC on the 4 gas analyzer. Even the latest new car would pass Californy emissions with those numbers.

[bobioknight]

Lots if great info to consider for sure. When I advance my timing up to 12 or close I do get closer to 20in of vacuum instead of the 19in at the 6*, but I can't lower my idle on the carb enough, only drops to around 580 rpm. Even at higher advanced I have not experienced any knocking or pinging. However I did have it way to retarded once with 21in of vacuum but experienced lots of pinging, so I brought the advance back to 6* and left it there.


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[40 Deluxe]

Don't overlook the fact that we're only talking about initial timing here, which is only seen at idle. (Obviously we don't idle going down the street/highway!) Above idle, timing is controlled by the centrifugal and vacuum advance mechanisms. The amount of centrifugal advance is controlled by the size of the weights and amount of spring tension. Vacuum advance is controlled the size of the diaphragm, spring tension against the diaphragm, and vacuum source. If you have a Motor or Chilton shop manual with distributor specs, you will see that the same size engine will have different advance rates (curve) depending on the vehicle it's in, transmission type, 2 or 4 bbl. carb, etc.
If you or former owner swapped distributors, or rebuilder threw in whatever springs he found on the floor, or it's just worn out, your timing at operating speeds is likely to be off, no matter how much you fussed over setting initial timing!

[Talkwrench]

If you want to run 12 * initial you will have to modify the timing plate as you will be too far advanced in your total timing and it will ping.

[willowbilly3]

Originally Posted by 40 Deluxe

Don't overlook the fact that we're only talking about initial timing here, which is only seen at idle. (Obviously we don't idle going down the street/highway!) Above idle, timing is controlled by the centrifugal and vacuum advance mechanisms. The amount of centrifugal advance is controlled by the size of the weights and amount of spring tension. Vacuum advance is controlled the size of the diaphragm, spring tension against the diaphragm, and vacuum source. If you have a Motor or Chilton shop manual with distributor specs, you will see that the same size engine will have different advance rates (curve) depending on the vehicle it's in, transmission type, 2 or 4 bbl. carb, etc.
If you or former owner swapped distributors, or rebuilder threw in whatever springs he found on the floor, or it's just worn out, your timing at operating speeds is likely to be off, no matter how much you fussed over setting initial timing!

Great advice. This is why I generally set timing with a good dial back timing light and hand held vacuum pump. The "all in" number is actually just as important (if not more so) that what the initial timing is set at. And with the dial back light, you only need a good chalk mark at TDC on the damper, everything else you read on the light.

[bobioknight]

I don't see how to adjust total timing, I don't see springs or weights inside the distributor. There is only the vacuum pod sitting on the side that slides the plate back and forth with vacuum from the carb. I'll crack the book open. I do also have the adjustable light and vacuum guage. I use them both to make my adjustments. I did verify that the 1st cylinder was at the top of the stroke when the timing mark was at tdc.

[dmsfrr]

Originally Posted by bobioknight

I don't see how to adjust total timing, I don't see springs or weights inside the distributor. There is only the vacuum pod sitting on the side that slides the plate back and forth with vacuum from the carb. ...

just FYI.
The initial distributor timing is set with the vacuum line to the distributor disconnected and capped or plugged.

Timing advance / total timing is a function of the hardware pieces inside the distributor, added to the initial timing.
The 'centrifugal advance' weights and springs are located under the plate the points are mounted on. The 'vacuum advance' has misc. springs and spacers inside the hex shaped chamber/fitting the vacuum line from the carburetor attaches to.
It is possible to change the various; weights, springs and spacers to alter the advance curve and total timing but they aren't considered 'adjustable' in the usual sense, unless you have lots of substitute pieces to swap in and a distributor machine to read the results of your changes.


first photo is just a similar example, not '57 T-Bird
2nd & 3rd photos are the real ones
.

[40 Deluxe]

Originally Posted by bobioknight

I don't see how to adjust total timing, I don't see springs or weights inside the distributor. There is only the vacuum pod sitting on the side that slides the plate back and forth with vacuum from the carb. I'll crack the book open. I do also have the adjustable light and vacuum guage. I use them both to make my adjustments. I did verify that the 1st cylinder was at the top of the stroke when the timing mark was at tdc.

The centrifugal advance mechanism is under the points plate.

[40 Deluxe]

There is a 'window" (hole) in the points plate for adjusting spring tension on the centrifugal weights. Turn the distributor shaft until you see a spring post. There are two, one has a heavy spring and one has a light spring. The heavy spring usually has slack in it. It controls higher RPM advance. With a small screwdriver you can bend the posts to custom tailor the advance rate.
Also, the weight mounting plate has two slots, one allows more advance than the other. They may be marked with something like "10" and "12" or "11" and "13". If you want more initial timing, use the slot with the lower number to avoid excessive advance at high RPM. Early vacuum canisters have a removable end fitting with shims to adjust vacuum advance amount and rate. Late model canisters are sealed but you can remove the hose and use an Allen wrench to adjust spring tension.
So, if you like to fiddle, you can do a lot with these Ford distributors!

[dmsfrr]

Originally Posted by 40 Deluxe

There is a 'window" (hole) in the points plate for adjusting spring tension on the centrifugal weights. Turn the distributor shaft until you see a spring post. There are two, one has a heavy spring and one has a light spring. The heavy spring usually has slack in it. It controls higher RPM advance. With a small screwdriver you can bend the posts to custom tailor the advance rate.
Also, the weight mounting plate has two slots, one allows more advance than the other. They may be marked with something like "10" and "12" or "11" and "13". If you want more initial timing, use the slot with the lower number to avoid excessive advance at high RPM. ...

I've got two '57 T-Bird distributors and not noticed any '10-13' markings or slots on the lower plate before, I'll have to look again next time I'm in there.

https://www.ctci.org/gilsgarage/57distributor.php
.

[willowbilly3]

Originally Posted by 40 Deluxe

Don't overlook the fact that we're only talking about initial timing here, which is only seen at idle. (Obviously we don't idle going down the street/highway!) Above idle, timing is controlled by the centrifugal and vacuum advance mechanisms. The amount of centrifugal advance is controlled by the size of the weights and amount of spring tension. Vacuum advance is controlled the size of the diaphragm, spring tension against the diaphragm, and vacuum source. If you have a Motor or Chilton shop manual with distributor specs, you will see that the same size engine will have different advance rates (curve) depending on the vehicle it's in, transmission type, 2 or 4 bbl. carb, etc.
If you or former owner swapped distributors, or rebuilder threw in whatever springs he found on the floor, or it's just worn out, your timing at operating speeds is likely to be off, no matter how much you fussed over setting initial timing!

That's good stuff to know about the weights and springs. On stock street engines I always found the centrifugal advance to be pretty close to factory spec but have used the allen wrench to adjust the vacuum advance, especially when installing a new one, they can be way out of whack since they fit a lot of applications.
Another thing to consider, check the sideplay in the shaft. If it's sloppy, the bushings are worn and you really have an engine you can't fine tune. As the shaft wobbles, the points gap changes, hence the timing and dwell are also changing.

[dmsfrr]

Originally Posted by willowbilly3

... Another thing to consider, check the sideplay in the shaft. If it's sloppy, the bushings are worn and you really have an engine you can't fine tune. As the shaft wobbles, the points gap changes, hence the timing and dwell are also changing.

If you have a dwell meter hooked to a running distributor and the reading bounces more than 3 to 5 degrees it's an indication of worn out bushings.