Think about it; if your ignition timing really was; 50* After TDC, it would likely not run. Actually, I don't see how it can.
As to reverse polarity;
when that happens, in my experience, the spark, as soon as you try to rev it up, becomes random. You will get strobes timed very late, strobes very early and strobes randomly jumping everywhere in between.
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BTW,
What your engine likes for idle timing and what you can actually give it, for a streeter, as you found out, can never be the same. If you actually test it, you will find that at idle, most performance engines will actually like 25 to 35 degrees of Idle-timing ..... or more.
But you can't give her what she likes unless you have an automatic with a hi-stall, and/or race-gears in the back, cuz trying to drive it slowly, especially with a clutch would be between very difficult and impossible.
And the reason is, that to idle at a reasonably slow rpm with 35* of Idle-timing, the throttles will be nearly closed, and the Transfer slot as good as shut off. Thus, as soon as you tip the throttles in, you will experience the dreaded tip-in sag, if it doesn't flat out stall.
I can tell you that, in my 367, even the 292/292/108 Mopar cam will idle just fine at 5* of advance, even tho it liked more than 25. At 5* she would idle down to 550 in gear and pulling herself across the parking lot (manual trans); a thing that was impossible at even 18*. Well, it would sortof do it, but she wouldn't take throttle ....... cuz the transfers were shut off.
So then, I get it. If you have a lo-stall, the engine is gonna be more fun to drive with lots of lo-rpm timing; I understand that. But trying to get it to take throttle from a normal idle speed with extra idle-timing, becomes more and more difficult, as the throttle closes, because of the stalled transfers.
My solution was a two-stage timing curve. A fast curve coming off idle that switched just before detonation came on, to a slow curve the rest of the way.
If you have a manual trans, this is the way to go.
My curve starts right off idle ~12*, and ramps up to 28@2800; then changes to just 34* by 3600.
In this way I can run 87E10 full time without detonation, even at WOT. and Also, in this way, I can properly set my Transfer slot exposure under the throttles, to avoid the tip-in sag.
With an automatic, really, the first time the engine cares about timing, is at stall. With a properly set transfer-slot, it will idle on just about anything you give it short of going retarded.
If your stall is 3500, you can probably lock the dizzy WFO.
If your stall is 2000, yur gonna have to claw it back to avoid detonation. With a non-stepped advance curve, designed to connect those two dots (stall and Power at 3500), Idle gets what it gets. This is NOT ideal, because at idle, with a properly synced Transfer-slot, the idle-advance controls the idle-speed. If you try to do it otherwise, you will quickly run into the tip-in sag. If you try to cover that with pumpshot;
Firstly your City fuel consumption will suffer big time, and
Secondly, good luck getting the accelerator pump to start early enough, and still have something left over for later.
And Thirdly is WHY? Give your engine what she will accept and not one degree more.
Your engine has Four major timing requirements
1) Power-Timing, usually at or near 3600 rpm
2) Stall-Timing, somewhere between 1800 and say 3000.
3) Part-Throttle Timing; anywhere from idle to say 3500
4) Cruise-Timing, somewhere between 2000 and 3000.
>Power-Timing for the SBM is always the same and for factory iron heads, is always, or should always be, in the window of 34 to 36, 37 at most.
>Stall Timing varies, and is determined by testing. A good guess is 1 degree or less per 100 rpm beginning at 20*@2000
> Cruise timing, for most combos, is gonna be in the window of 50 to 56 degrees, depending on; the rpm/load/engine efficiency/etc. Unless you have an overdrive going down the road at 1600 or some equally insanely low number, lol.
> Part throttle Timing is gonna depend on your skills a a tuner, and will depend a lot on your ability to get the AFR in a tight window. Thus, if you set the Idle-Timing too high, yur gonna have trouble dialing this in.
The Mopar V-can, can be modified to top out at 22>24 degrees, and you are gonna need all of that for optimized cruise timing.
Thus, if you are cruising at say 2400rpm, and your Power-Timing is 24*, then adding 22* from the Vcan, totals just 46* which may or may not be correct for your combo.
But if you have set the Idle-timing to 22, and the mechanical has brought in 16 by 2400, and the VA is 22, now you have 60* which in all but a few cases is gonna be too much. So again, WHY try to run so much Idle timing? You are, IMO, just making the ignition tune harder than it needs to be.
