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![]() Heck you could use the ignition timing marks in place of TDC when adjusting valves, it won't make a difference for valve gap adjustments. So you can skip this and just place the TDC mark at the bottom of the pulley when setting valve gap for #2 and #4 that works just fine. If you are off by a few deg when setting valve gap it will not make any difference. Valve setting marks do not need to be super accurate. This will be helpful when setting valve gap. While you are in there, you may want to place your tool into spark plug #2 and make a mark for BDC 180deg off from TDC. Divide this length by 360 and multiple by 28 and 32, respectively to find the arc length to make these marks CW from TDC. Use the diameter of the pulley xPi to work out the circumference. That one is now at the bottom of the spares box. I ran into one (used) 009 than didn't fully advance until 4000RPM, almost 7 degrees more advance between 30. 5deg to either side of the TDC point.)Īll you need to do now is calculate the distance around the edge of the pulley from TDC to 28 and 32 BDTC. A quick check to be sure the distributor is fully advanced is to rev it to 3000, set timing, then rev to 3500 and be sure the timing doesn't change. The only thing that might have made it slightly more accurate is using stop points that were much closer to TDC (eg. ![]() The method you described is the most accurate way of finding TDC. The good thing is you now know exactly where TDC is on your crank. The very last pulley pic is the late 70's Beetles which only came with two notches. See the below link which highlights the different pulley's and their markings. That pulley may not have a TDC "dimple" on the rear facing lip (rear of car). The two notches are (as 67rustavenger pointed out) 7.5 and 10BTDC. The only issue was your assumption that one of your timing marks was TDC. Posted: Sun 3:25 pm Post subject: Re: Timing marks - 1500 SP Unless you're dialing in cam timing there is no need to be any more accurate than this, for ignition timing and valve adjustments it will be close enough.Īn ounce of prevention is worth a pound of cure. Use your pulley mark spacing to extrapolate TDC by extending the factory marks to the left 2.5* times three. Only some year/model pulleys are marked with TDC and your's is not one of them.Įyeballing your 1/2 way mark appears to be about TDC. Hard to say 100% from angle of photo but yes, that looks about right.Īs 67rustavenger said, right factory mark is 10* Before Top Dead Center, and left mark is 7.5. Posted: Sun 3:23 pm Post subject: Re: Timing marks - 1500 SP
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