WTF did that guy just say?
Anyway, back to planet earth,
Your distributor for a SBF car with 4 barrel by any chance?
"With timing at 0 BTDC almost no pinging (what is there starts at approx 2500 RPM.) and the throttle response and low end sucks. Around 8 degrees initial timing the bottom end is strong and extremely responsive. So, time to screw with the advance."[
First off, you don't have the best cam for slow off roading, so I'm assuming you are using this vehicle for street driving also?
My guess is you are getting too much mechanical advance.
You can try a couple of things,
First off, keep your initial timing at about 8° BTDC, that is a good, calm place to start.
Since you are happy with the idle and off idle performance, this is the hot ticket
Make sure your vacuum advance is unhooked and the line is plugged when you set the timing.
Secondly, move your vacuum source to a 'Spark Ported' supply.
Third, Hook up the vacuum and see how much vacuum advance you are getting at idle. We'll need to know that to do this properly.
Fourth, Unhook the vacuum and plug the line again.
Rev up the engine and see how much advance you are getting from centrifugal.
Fifth, leave the vacuum unhooked, drive it a little bit, see what it does.
Now, If your vacuum advance has 'Flats' just behind the vacuum line nipple, you have an adjustable vacuum advance from the factory.
There are two kinds, An Allen wrench type, and a flat blade screwdriver type.
The Allen wrench type is much more common...
You can limit the total vacuum advance by moving the screw in and out.
You will have to reset initial timing after you make changes.
The Centrifugal advance is somewhat harder to get at...
It's in the bottom of the distributor, under the mag trigger/advance plate and floor plate.
In this image, marked R13 & R18,
These denote the amount of advance each slot will allow. (Amount of Centrifugal Advance)
You can take some top end out of the advance by retarding or limiting the amount of travel in this slot.
You should also notice the springs.
Larger springs won't give you less advance, but it will make the advance you do have come in later (Timing of Centrifugal Advance)
If you need new springs, try Mr. Gasket part number 925D. This will give you a selection of springs so you can try different combos.
If you don't have a balancer that shows your total advance (many don't), you can solve this problem easily.
Measure the distance from the 0° mark on the timing tab to the 10° mark.
Transfer that distance to the balancer starting at the regular timing mark and moving to the left (before TDC).
Do that about 3 times and you will have 40° of timing marked, and that should be enough for a SBF.
Read your new mark on the timing tab like it was the original, but don't forget to add 10° for each mark you go past on the way to the totals...
(Example, 1 new mark plus 2° is 12 degrees total.
2 new marks plus 5° is 25° total.)
Now, here is something you need to know...
In the center of the advance head (copper part shown in picture) there is a steel shaft.
(It will be covered by a lubricating 'Felt' in a stock distributor.)
Around that steel shaft is a very small wire clip that expands to get it out.
DON'T LOOSE OR BEND THIS WIRE CLIP!
This is what holds the advance head on the distributor shaft, and without this, you are screwed! There isn't anyplace to get replacements, so be careful and use a magnet!