pstroke7.3

I have a 95 GTS with a 5.0 HO motor. I recently traded the stock intake and fuel injection for a performer 289 intake and a 4 barrel carb.
I took out the stock ignition and opted for a 1 wire distributor. I have the timing set for a normal 302 1-5-4-2-6-3-7-8. Well I can get the motor to start and run with this order but i'm having some serious backfire and random popping in the exhaust and intake backfire. I have my timing set as 10 degrees before top dead centre. I have read different places that the 5.0 HO motors actually use a 351 firing order. I tried changing my plug wires to 1-3-7-2-6-5-4-8 but I couldn't even get the motor to start. I wonder if I don't need to try new plug wires and plugs and try that. The car starts right up with a normal 302 firing order but it pops and pings at random times and idles pretty rough. Giving it any gas results in even more backfire. I'm at a loss for what this could be, any help or information y'all have would be greatly appreciated. Thanks

pstroke7.3

After looking into this a little further I have noticed on all the firing order diagrams It shows the distributor turning counter clockwise. I have my wires arranged in the opposite of this order. My plug wires are arranged in the standard 302 firing order with the distributor turning clockwise. This makes me wonder if the diagram is correct how the engine is even running being arranged how I have it. Just a thought here at work but until I can get home and try this I wanted to put it here to see if anyone else had input.

08'MustangDude

This should be correct:

pstroke7.3

Thanks so much. After looking at this it looks like I had the old 302 firing order and I had it on the distributor as if it spun clockwise. Not sure how it even started up and ran like that LOL but After I changed it to the 351 firing order and for a counter clockwise spinning distributor she fired right up.

wbrockstar

I cant believe it ran either,with a totally backwards plug wire orientation.
BTW- the camshaft is what determines the firing order.The 95 HO cam uses the 351w/302HO firing order while the older 302's used the Non HO/standard firing order. The standard firing order would have only worked if you removed the HO cam and replaced it with a Non HO cam.Well actually,if you would have wired the cap with the 15426378 firing order,but placed the wires in a CCW direction (instead of the CW direction you used) on the cap,the engine would have started and ran,but driveability issues would have occurred.The following shows how the injectors are fired for both firing orders.
P= passenger side injector
D= driver side injector
HO= 13726548
PPDPDDPD
NON HO= 15426378
PDPPDPDD
Do you see how the different firing orders will affect things injector wise?? How a D side injector firing when it should be a P side injector firing??

Earlier model 302 Thunderbirds,Cougars,
Crown Vics,etc also used the Non HO order. If you would have still had the efi system in place and wired the cap like you did,the car would've never started because the injectors are also fired in sync with the firing order (i.e.- each injector is fired individually with each spark plug)
The distributor is rotated CW to advance timing and CCW to retard it,but the rotor does indeed move in a CCW direction, when the engine is running.