Also very important in an air-cooled... if its too retarded you'll lose power, if its too advanced, your car will feel fast, but cook itself very quickly!
There are two methods for timing an aircooler, the static method, and the strobe method. both are easy, but I always stand by the strobe method as it shows you the ignition advance all through the rev range as the engine will be running, the static method only checks the timing at zero advance. I'll go through the strobe method step by step as I feel its the only way to really know if your engine is running right...
Buy a strobe light! Halfords sell em very cheaply, I use one made by Gunsons, cost me about £20 ... worth it if you're going to be doing all your own maintenance [what do you mean your not?! its easy! don't pay someone else to do it!]
Attach the power leads for the light to your battery terminals and attach the inductor module to number1 HT lead . if you don't know which lead that is, take your distributor cap off and look for a notch in the top of the dissy body [front right hand side].. the lead above this is number 1!
Step 3: Look on your bottom pulley for a dent in the outside edge of it. On the inner part of the pulley, just to the right there is sometimes a smaller notch.. mark these with tip-ex or white paint
Gentlemen! start your engines!! ...and let it idle.... as soon as you fire it up, the strobe will start flashing, highlighting your fresh marks. point it at your bottom pulley, and if all is well, the marked dent on the outside of the pulley should line up with split in the middle of the engine casing behind it...as you increase the engine revs, the white mark should move anticlockwise..[this is ignition advance in action! if it doesn't move, your distributor is knackered, and your engine will run badly] if you have the second mark on the inside of your pulley, this should not move beyond the split in the engine casing no matter how hard you rev it. If all lines up well, then stop right there! job done!
So the white mark didn't line up??!?! well your timing was out then!! to adjust it, turn off your engine and look under your distributor, there should be a 10mm nut attached to a collar that goes round the base of the dissy [NOT the 13mm nut at the back of the dissy that holds it into the engine] once you've found it, loosen it.... the dissy will now turn in its housing. start it up again, and turn the dissy, you'll see that as you turn it, the mark will move from side to side, line it up with the split in the casing, turn the engine off, tighten the collar again[do this up very tight and it wont budge for a while!] et voila!! remove your strobe, and grab yourself another one of those cold tubes from the fridge!! this is fun now isn't it?!
A quick aside, I've not had to adjust my timing settings for over 40,000 miles now, I just check it every 3000 to make sure its still spot on, but if that dissy collar is nice and tight, and your points don't wear out, [or if you've got electronic ignition fitted?!] you shouldn't have to re-adjust it.....