IIRC you said you had a 2200ish stall. and 3.73 gears. That's gonna put a damper on how much timing you can run down there and still get to around 36*@ say 3400 rpm
That long-loop spring is only good for about 4>6* and some that I have tested took to 4000 rpm to be all in, with the stock weights. If you have a problem with detonation that can help, but mostly, that is unacceptable even in a 360.
I had a small selection of those long loopers, that I had accumulated over the decades, and so I rigged up a test-apparatus to weed out the late-bloomers, until I found one that seemed appropriate. It turned out to be just what I needed. Well I had to stretch it out a tad.
After that I just began installing the singles , one atta time, until I got what I thought would work. Each time, I had to generate a graph to see how it turned out, and to compare the current springs and weights, to the previous. Then began the roadtests...... for which, I had previously installed a dash-mounted, dial back, timing module, and with an on-board accelerometer, I was able to generate a pretty good theoretical timing curve to work against. By the end of the summer, I was reasonably pleased.
What I learned was this; at WOT;
3* short of ideal, from stall to 3600, is hardly noticeable. It's like less than 5hp max.
2* too much, when it causes detonation, you can feel it almost right away.
Therefore; if you can get the PowerTiming within a degree or two, and the stall-Timing even just close, but not too much,
Then, your engine will be happy. How it gets from stall to 3600, can be whatever; because the window, is very small, and in First gear, you scoot right thru it, and if you out-shift First at 5500, it will drop into Second at 3250, so just make sure, it doesn't detonate there..
At WOT
suppose your engine accepts 35* at 3400 rpm without detonation. and
suppose your stall rpm has to be less than 24*, and
suppose your T-slot sync ends up being 12*.
Your job is to connect those dots. So you gotta put the points on a graph. Then if they cannot be connected with a straight line, you have two choices;
1) run the 35* at 3400 and let the rest be what it will be. or
2) run a two stage curve, with the first curve connecting the Idle timing to the stall timing, then into the long-loop spring, ending as close to possible to your target of 35*@3400 rpm. Sometimes it is just not possible to do that with the parts you have. Sometimes, you have to make a compromise.
This is one of the reasons I like the 2800 stall convertor, it puts the stall rpm closer to what timing is achievable with factory distributor parts, and you don't hardly have to compromise .
Plus, you know, by 2800, the SBM is starting to make some half-decent torque, lol................................. which makes for a fun launch.
