Re: Advance timing??

Posted by Fish'n Jim On 2023/12/9 11:09:14

I suggest it's better to find out why your car is not starting 'well' than fiddling with the timing. Quick fixes are just that - don't solve problems. I define 'well' as it turns over and fires right off. No prolonged cranking or multiple start attempts. Most of these old cars, need a few turns to bring up the oil/fuel pressure before intro of spark. Look at the starting procedure for your car. Carb design influences starting procedure too.
Perhaps it's not timed correctly to begin with or some issues with the spark or fuel circuit, starter drawing too many amps/battery not outputting, etc. These old carb/points cars should be "tuned up" about every year regardless of miles driven for max starting performance.
It has little to do with the nominal system voltage, per se, 6 vs 12, as many of the ignition system coils ran on 6V well past the advent of 12VDC cars. Aka ballast resister cars and then they moved the resister internal to the coil later.
Timing is just the marriage of spark to piston position in degrees. If it's "too early" then the fuel charging won't be complete before it starts to burn or to much not burn at all. ie backfires thru manifold. Yeah, burn, not explode.
If it's too late, then some unburnt will leak out before it's ignited or not ignited it won't start if too much.ie can backfire.
It's fantasy to think that only when it's @ TDC that the spark needs to be there.
Now figure in rpm's and things change.
There's less time to complete the 4 cycles. It's better to be a little before(anticipate firing) than late with a mechanical system. Electronics(HEI) often fire multiple times instead of the mechanical once so are more reliable/less sensitive. If you ever watch a top fuel dragster, there's fire coming out the headers, even at idle, not clean completely burnt exhaust. And they use two magnetos for max. spark. The idea being to stuff as much fuel in there to get maximum HP a fast as possible, ignoring fuel efficiency or perfect timing. Cylinder pressure increase increases required spark energy. Often one cylinder will go out, white fuel spray out the exhaust header during the run and cause mechanical damage. But that's for illustration, not factory P's.
All my reading, SAE reports, etc always attribute the start up period as the highest documented engine wear period. That's why highway miles are less damaging than start/stop driving. That momentary lack of lubrication increases frictive wear, until the oil gets flowing.
to illustrate: Many antique tractors had roller bearing bottom ends, not traditional solid bearings or babbitt for longevity. How it was constructed will determine more it's design life than ignition timing. The evolution, progressed to pressure lubrication & oil filtration to extend engine life. It started off mostly as splash oiling, or 'oilers' and frequent oil change or once through oiling.