Ford 300ci firing sequence

Chuck52 · Oct 3, 2005

Attached (I hope) is a drawing of the distributor cap for a Ford 300ci engine, giving the firing sequence. Anyone running one of these? My 1991 F150 is giving me problems, and I've changed the ignition wires and cap and rotor. I kept track of terminal number one, but the orientation of my cap relative to the block is different from in the drawing. The attachment tabs are rotated about 45 degrees counter-clockwise relative to what is shown, but the number one terminal is just slightly displaced relative toi the drawing. The drawing is from my Chilton manual, and I also checked Mitchell and another brand manual, and all agree. The cap I replaced had the number one terminal marked, and I can refer to that to set the new cap, but I was wondering about this discrepancy. Would the engine run at all if the wires were displaced? It was running fine before the trouble started, and I don't think the wires jumped themselves around!

BTW, I call this truck my PIAUV, where the UV stands for Utility Vehicle. I do use it to haul tractor stuff....when it's working, anyway!

OK. So it's upside down. At least it can be read.
Chuck

SimS · Oct 3, 2005

Chuck;
Why don't you bring it up to TDC on #1, check where the rotor is, call that #1 and wire the rest up in sequence?

Good Luck;

Sim

ScottAR · Oct 3, 2005

Every time I mess with ignition systems it's always the loose nut standing on the ground that causes the problem. /forums/images/graemlins/blush.gif

#1 is at the front as you know.

I usually do what Chuck suggests. Roll #1 up to TDC and start wherever the rotor stops. On an inline 6 ford the dizzy gets wired in a clockwise manner. (153624) V8s are counterclockwise.

Mike_C · Oct 3, 2005

#1 on the old cap should be in the exact same location as #1 on the new cap. If they are different, I'd say you have the wrong cap.
If you still want to use the new cap, the only way to get it to run is to follow the advice given in the previous message that says to bring the number 1 piston up to TDC in the firing position (both valves closed), then see where the rotor points. That is where the #1 plug wire should go. You may have to turn the distributor, but if you are not familiar with how to set the timing then you may not want to do that. The drawing is for reference but is not absolute. While rotating the distributor to change the timing, you could easily account for the discrepancy of the drawing.

Chuck52 · Oct 3, 2005

As I was leaving work, a guy pulled up in a mid-90's F150. I asked if he happened to have the straight six in there, and he did. So we popped the hood, and the distributor cap arrangement looked just like mine. I kept track of which was the number one terminal all along, but since I've had a few senior moments of late, I had started to doubt myself. It looks to me as if all the manual writers use the same "approximation" for their drawings. As I said, one of the manuals seemed to imply that the orientation of the mounting tabs was both correct and important. The position of the number one terminal in the drawing is indeed close enough to the correct position that you might get there by adjusting the timing, but if you tried to use the positions of the mounting tabs to indicate the position of the number one terminal, you'd be waaaay off.

So, now I've got to figure out where the short in the fuel pump power line is. Automotive electrical problems are fun. The guy who let me see his engine told me he had the same wet weather problems I described sometimes. His truck is a '95, with the original wires, so I suggested his ocassional problems might be fixed by a new set.

Chuck

RobertN · Oct 3, 2005

As you change your wires and reroute stuff, double check your manual carefully.

On my old F250, I changed the cap/rotor/wires/plugs. I fired it up and it ran terrible. Turns out, the wires had to be a specific order in the looms/holders. If they crossed over each other incorrectly, they would cross-fire. I double checked everything, and rechecked the manual. Sure enough...

This was on a 400-v8. But, I have only seen this on a Ford; never seen it on any other brands.

Something to watch for...