I have a 1971 C20 350 SB. I am a novice DIY mechanic. I just rebuilt the top of motor (camshaft, lifters, push rods), put all back together, cleaned carb, new HEI distributor, plugs, wires; hooked harness wires back and not getting any spark. I did cut off an extra yellow wire of two that was split from one pink wire from cab. It was running after cutting wire before rebuild. Now crank but no spark or start. Please help!