This is based on old info.... Built a lot of sm block chevs and a few big blocks back then, pre 1975. Far as I know T D C, firing order & Dist position remain the same. Timing marks are on damper front of crankshaft & scale attached to block. Sounds like your vision is blocked from top side? Couple things to remember.1st, Camshaft drives dist & oil pump. Crankshaft makes 2 rotations for every 1 on the cam. That means with crank on T D C you have a 50 50 chance of installing the distrubtor exactly 180 degrees off. No harm no foul, just lift dist up above the cam gear and rotate dist shaft 180. 2nd, Dist shaft gear engages cam gear AND end of shaft engages a slot in the oil pump shaft. Its very common for the oil pump shaft to be a wee bit off to align, just use a large flat screw driver to go down and "tweek" the sloted shaft a bit, rotates easy. Takes a few times on occasion but you'll get it. 3rd, finding T D C without marks. Take out #1 sparkplug use a long rod, coat hanger works, but LONG enough not to loose it. drop in to top of piston, rotate engine untill piston "tops out". You now have it BUT with the 50-50 off 180 chance. You can take the valve cover off to see the valves, if both are closed you got it. Or don't. If engine starts you got it, if not just rotate dist shaft 180 & you got it. You can use # 8 or any others but it can be a *****, especially the 1st time w/o help. Useing the damper mark and block scale on TDC really is the easy way and you're gonna need them to time it any way. While you're in there put some white paint on the marks, makes timing that much easier to see.
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