Firing order info - interesting....

[coz 108]

Not sure but I believe the 351W has the same firing order as the 351C - maybe other engines also. The Cleveland firing order is 1,3,7,2,6,5,4,8. And I assume the piston order is the same 1-4 on the pass. side / 5-8 on the drivers side.

 

Found out some interesting things about misfires with plugs 5 and 6. Seems that since they fire one after another (6 then 5) that 6 can arc to 5 and cause premature detonation creating a weak 5 plug detonation.

 

So it's recommended you not run the 5 and 6 wire side by side - even in looms or separators. It's best if you route 6, 7 and 8 over the valve cover and 5 around the front of the head and onto the plug.

 

Found this very helpful since I plan on redoing my plug wires with a custom cut length. Would have sucked to find this out after I cut the wires....

[bnickel 10,004]

if you ever look at the factory wire routing on a 351 you'll notice that 5 and 6 are swapped in the loom on the valve cover to help prevent crossfires.

[351carlo 10]

I was reading that on .net too.... but I've never experienced that issue. Maybe the wires I'm running are of higher quality and don't arc, or I just never noticed it.

[bnickel 10,004]

i've never has a problem and i don't even do the factory loom swap. i think it's realy only a problem in the upper RPM ranges anyway, probably over 5 grand really.

[coz 108]

i've never has a problem and i don't even do the factory loom swap. i think it's realy only a problem in the upper RPM ranges anyway, probably over 5 grand really.

 

 

B,

 

5k is where I really begin to play and I've had some "hesitation" over 4k in the past. I think most of that was carb/fuel issues that since have been fixed.

 

So is the arcing issue with 5 and 6 crossing around the cap and not farther down? Meaning, if you swap 5 and 6 on the loom they will still have to cross prior to the plugs. I'm using MSD 8.8mm wires and NGK non-resistor plugs so maybe this isn't an issue. It's just that it's above freezing finally around here and I've been lazy so it's time to do some engine straightening up and cleanup - new plugs, wires, carb jets, etc.... Prior to the tranny / rear swap.

[351carlo 10]

I did have a crazy hesitation around 5500 before I switched to the MSD box and Accel 9000 wires. Perhaps that was the issue....

 

And it is DEFINITELY too cold to be working on mustangs in the Northeast/mid-atlantic

[R4K 10]

FEs (firing order 15426378) have the same problem with 7 and 8.

 

I didn't know this last summer and am wondering if that had something to do with my random backfiring/stumbling issues I was experiencing...because I rearranged my wires in the loom not too long before that to make them look "prettier", and ended up putting 7 & 8 next to each other, lol.

[JC69Stang 0]

Yeah, the old chevys had the same problem, keep 'em nice and seperated and you should be good to go!