I have been working on the timing on my 250. I went ahead and put in a new cap, rotor, wires and plugs. I then checked the timing as I thought the car was still running a little sluggish, sure enough it was 3deg btdc! The sticker on the valve cover says 7. I bumped it to 9 and it ran a whole lot better but was wondering if I can go even more? It seems the more timing advance the better these engines run. How much advance can I safely go to with a stock engine?
This is a deep subject. I can only go 9* base timing on my 250 but I hot rodded my distributor up by using lighter advance springs and re-curved the vacuum advance. I would say advance it your distributor more degrees until you hear ignition ping under heavy load then drop it back two or three degrees. You might end up around 12-14 degrees or it could be around 10* when it's all said and done. What ever you do...don't keep it where you hear any pinging. Pinging will destroy an engine before you know it.
To go along with what Jeff has outlined above, a very easy trick with Fords of this era was that the advance springs in the distributor consist of a medium-weight spring along with a heavier one. If you rob another medium spring from another distributor, the two medium springs will bring the mechanical advance in at a much better rate, and you usually don't have to worry about it being overkill. If you get an aftermarket set of springs, many times those are drag-racing use only, and they might be too much of a good thing. The "proper" way to do this is to pull the distributor and find a machine that will map the advance curve ... fairly involved. What I described above is a quick and dirty way to get decent results that have fallen within good specs for me consistently.
Another timing advance thread? This subject seriously needs a sticky. lol Personally?.. I like major amounts of initial advance and slightly quick'ish.. but heavily limited travel(which is required for high initial settings or you'll go way overboard on the total timing number when revved). Heavy initial timing gives you more torque at idle - 1,600 rpm or so.. when the mechanical has not really contributed very much on its end. Basically.. "bigger nu"... errr.. "bigger guts" and much improved throttle response. In a nutshell.. you want to achieve the highest possible amount of manifold vacuum at idle and light cruise as you possibly can without the pinging mentioned above. To do that usually almost always requires the use on manifold sourced vacuum for the disty's vac advance pot. Timed sources off the carb will only give you supplemental vac assisted timing advance during light cruise situations. Which is better than nothing.. but not as good as vac assisted timing at idle.. AND.. light cruise. Heavy initial timing does not disappear like vac assisted advance does.. regardless of the vac source used.. which is why it's so advantageous for those quick throttle transitions from idle speeds.
