First, are you real sure you installed the cam properly, per the mfgr's instructions on cam-timing? If the cam is off relative to the crank, no amount of fiddling with the ignition (which is driven off the cam) will help. If the cam is OK, then you probably returned the distributor to the block a tooth or two off. You'll have to find top-dead-center ON THE FIRING STROKE. This is done by removing #1 spark plug and the coil high-tension lead from the coil, then 'bump' the engine a little with the starter until you get a loud blast of air out the open hole. Check the timing mark- it should be close to the timing pointer. With a socket wrench, back the engine up (but do NOT rotate it a full 360 degrees!) so the timing mark & pointer are aligned. Then remove the distributor cap; the rotor will be pointing to a post thats probably not what you have connected to #1 plug. It makes no difference at all which post in the cap is #1, as long as you start there and follow the 351-C firing order with the rest of the wires. AND- the 351-C community has been having a rash of aftermarket cams (all brands) that have the drive gear teeth cut slightly wrong. This will wear out a distributor drive gear in as little as 5 miles of driving. So its smart to drive it a ways, then pull the distributor and check the drive gear teeth. A bad cam will cause the distributor gear to wear to razor-sharp teeth, then quickly fail, and the longer you let it go, the more chips of iron drop into your oil & score bearings & cylinders. A total overhaul is the only fix if this goes on very long. Good luck.
