Firing Order

[coachbarnes]

How can I tell what the firing order should be on my Bronco? It has a '93 Mustang Fuel Injection, but I'm not sure if it's a 5.0 or older 302? Firing order for 302 shows to be 1-5-4-2-6-3-7-8, but the 5.0 shows to be 1-3-7-2-6-5-4-8.

I suspect it's the 5.0, but is there any way to be definitive?

 

[Viperwolf1]

Since the difference is determined by the cam lobes, the only sure way is to watch what the valves are doing to see if #3 or #5 follow #1 in the rotation. The position of the valves at #1 will be mirrored by one of those cylinders exactly 90 crankshaft degrees later. But it's a pain to remove valve covers with EFI.

Alternately you determine the order by pulling the spark plugs on those 3 cylinders. With your thumb over the #1 plug hole, turn the crankshaft CW until you feel pressure pushing your thumb off the hole. Exactly 90 crankshaft degrees later the same will happen to either #3 or #5.

 

[coachbarnes]

Since the difference is determined by the cam lobes, the only sure way is to watch what the valves are doing to see if #3 or #5 follow #1 in the rotation. The position of the valves at #1 will be mirrored by one of those cylinders exactly 90 crankshaft degrees later. But it's a pain to remove valve covers with EFI.

Alternately you determine the order by pulling the spark plugs on those 3 cylinders. With your thumb over the #1 plug hole, turn the crankshaft CW until you feel pressure pushing your thumb off the hole. Exactly 90 crankshaft degrees later the same will happen to either #3 or #5.

Thanks -- it's definitely a 5.0!

 

[jckkys]

No it's a 302. The label 5.0 was used long before anything was changed. So, 302s that Ford called 5.0s came with both firing orders. 1974 Mustang IIs had 302s Ford called 5.0s. They were just like any other '74 302s. The different firing order came in later but not all at once so the method Viperwolf1 explained is a good idea.

 

[coachbarnes]

No it's a 302. The label 5.0 was used long before anything was changed. So, 302s that Ford called 5.0s came with both firing orders. 1974 Mustang IIs had 302s Ford called 5.0s. They were just like any other '74 302s. The different firing order came in later but not all at once so the method Viperwolf1 explained is a good idea.

OK -- I've definitely got a 1-3-7-2-6-5-4-8 firing order 302.

 

[jw0747]

Seems you can also determine f.o. by checking the routing of the spark plug wires as they depart the distributor cap if #1 is clearly marked and the engine is running smoothly.

 

[Rox Crusher]

Seems you can also determine f.o. by checking the routing of the spark plug wires as they depart the distributor cap if #1 is clearly marked and the engine is running smoothly.

I think he was trying to determine if the plug wires were routed using the appropriate firing order for the cam that is in his "it's not a 5.0" 5.0.

 

[jckkys]

The point is that they are all 5.0s and 302s there is no accurate or honest description that can differentiate them as either one or the other. Lazy misuse of terminology never leads to effective communication.

 

[Bukin 67]

You working on the '74?

 

[coachbarnes]

You working on the '74?

Working on the '74 Stroppe. My LUBR is also a '74 - but it has a Ford Racing crate and I'm good with that one.

Finally think I have my ghost issue resolved, after replacing almost every part under the hood! LOL

 

[NYLES]

OK -- I've definitely got a 1-3-7-2-6-5-4-8 firing order 302.

5.0 HO uses 1-3-7-2-6-5-4-8 all others 1-5-4-2-6-3-7-8