My son and I are street rodding a 78 El Camino. It has a 267 small block. We just changed intakes (Edelbrock performer) and new billet distributer. We have triple checked the firing order, set the engine to TDC and routed our plug wires according to the firing order. The engine turn over fine (no back firing, but maybe just a little fast) but it will not start. What are we doing wrong ?