Firing order on the distributor for 302?

Answer 1

Ford used 1-3-7-2-6-5-4-8 for the 351W, marine, and roller cam Mustang HO series of 302 motors. Most other vehicles stayed the same initially. Around 1994, 302/5.0 trucks changed from early 289/302 to the 351W/later HO order of 1-3-7-2-6-5-4-8.

I've seen many people use the wrong firing order. Always check the manual, or write down the original wiring order. If you think something has been changed, like the cam, you can either try both orders or pull the valve covers and watch the valves move. If the very front cylinders on each side have the intake and exhaust valves closed almost entirely at the same time, you have a 289/302 firing order camshaft. If the valves are opposed as you turn the engine, it is a 351W/ marine/ late 5.0 HO order.

In all early 289/302 engines, Ford used 1-5-4-2-6-3-7-8. This fires 1 and 5 at the same time, which puts more twisting load on the crank front. This can cause crank failure, or front main bearing damage, under sustained heavy loads.

Ford used 1-3-7-2-6-5-4-8 for the 351W. The front two cylinders do not fire and push on the same crank throw at the same time. This is much easier on the crank and front bearings.

To reduce crank load at the front for HO 302's, Ford changed 302/ 5.0 camshaft grinds to the 351W and marine firing order. This was a transition, and appeared slowly in different engines, so you should check your specific vehicle.

This long explanation is necessary because of the firing order change that slowly worked its way through various 302 engines in various applications, and because some people think all you need to do is swap wires to change to the new firing order. Ford did not change everything all at once for everything.