Firing Order Mystery

[ccijwright]

Ok, let me start this by saying that my 351c runs ok, but I have a few "pops" backfiring when letting of the gas. The mystery is that my spark plug wires appear out of firing order! The plug from the #1 labeled spot on the distributor cap goes to the #7 cylinder for instance and the plug from the #1 cylinder goes to the #7 on the distributor. #1 on the distributor is normally on the #1 cylinder correct? So, of course the others are all out of order too. I know the PO put a cam in it, could that be the issue? I did wire it according to the manual, but it sputtered and did not start. Wired is back the funky way and it fired right up??? Please Help, any ideas? Thank you-

 

[mjlan]

Sometimes the distributor can be installed such that the rotor isn't pointing to tower #1 when cylinder #1 is on it's compression stroke and need a spark. It's a short cut to just move the wires around the cap one position instead of pulling the distributor out and moving it a tooth on the cam to get the rotor to line up with the right cap tower.

Maybe this is the issue?

 

[ccijwright]

Sometimes the distributor can be installed such that the rotor isn't pointing to tower #1 when cylinder #1 is on it's compression stroke and need a spark. It's a short cut to just move the wires around the cap one position instead of pulling the distributor out and moving it a tooth on the cam to get the rotor to line up with the right cap tower.

Maybe this is the issue?

Ok, so you are saying they may have the distributor off by a lot because the #1 cylinder is going to # 7 on the cap?

 

[jbojo]

Sometimes the distributor can be installed such that the rotor isn't pointing to tower #1 when cylinder #1 is on it's compression stroke and need a spark. It's a short cut to just move the wires around the cap one position instead of pulling the distributor out and moving it a tooth on the cam to get the rotor to line up with the right cap tower.

Maybe this is the issue?

Ok, so you are saying they may have the distributor off by a lot because the #1 cylinder is going to # 7 on the cap?

The firing order is 1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 and the distributor rotates CCW. So find the spark wire from cyl 1 and the next wire should be cyl 3 when going CCW, etc.

What mjlan is saying that the previous owner just didn't line up the dizzy when it was installed to line up with the #1 mark on the cap.

 

[ccijwright]

Sometimes the distributor can be installed such that the rotor isn't pointing to tower #1 when cylinder #1 is on it's compression stroke and need a spark. It's a short cut to just move the wires around the cap one position instead of pulling the distributor out and moving it a tooth on the cam to get the rotor to line up with the right cap tower.

Maybe this is the issue?

Ok, so you are saying they may have the distributor off by a lot because the #1 cylinder is going to # 7 on the cap?

The firing order is 1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 and the distributor rotates CCW. So find the spark wire from cyl 1 and the next wire should be cyl 3 when going CCW, etc.

What mjlan is saying that the previous owner just didn't line up the dizzy when it was installed to line up with the #1 mark on the cap.

Ok, then my #1 cylinder wire goes to # 4 cylinder on the distributor cap. It runs ok, which is the mystery.

 

[jbojo]

Ok, so you are saying they may have the distributor off by a lot because the #1 cylinder is going to # 7 on the cap?

The firing order is 1 - 3 - 7 - 2 - 6 - 5 - 4 - 8 and the distributor rotates CCW. So find the spark wire from cyl 1 and the next wire should be cyl 3 when going CCW, etc.

What mjlan is saying that the previous owner just didn't line up the dizzy when it was installed to line up with the #1 mark on the cap.

Ok, then my #1 cylinder wire goes to # 4 cylinder on the distributor cap. It runs ok, which is the mystery.

Bottom line, #1 position can be any spot on the cap as long as when the #1 cyl is on the compression stroke at 12 degrees BTDC and the rotor is pointing to that wire then all is good as long as you have the firing order correct. Some caps don't even have a 1 stamped on them. If you want the # 1 mark on the cap to correspond to the #1 Cyl then you are going to have to remove the distributor and realign the rotor to match that spot. Again you must make sure that #1 cyl is near TDC as mentioned above before pulling the distributor. The motor appears to be running correctly so all should be good. I would just leave it IMHO.

 

[Mikes73]

I would take the distributor cap off, bump the engine over to find top dead center on #1 cylinder, check and verify the timing mark is at around 0* BTDC on the balancer, see if the rotor is pointed towards or a little bit clockwise of where the #1 dizzy terminal on the cap would be. If not, restab the dizzy with the rotor pointing towards #1 on cap, verify and/or correct the sparkplug wire routing and retime the engine.

 

[jbojo]

I would take the distributor cap off, bump the engine over to find top dead center on #1 cylinder, check and verify the timing mark is at around 0* BTDC on the balancer, see if the rotor is pointed towards or a little bit clockwise of where the #1 dizzy terminal on the cap would be. If not, restab the dizzy with the rotor pointing towards #1 on cap, verify and/or correct the sparkplug wire routing and retime the engine.

Yup that would do it. Remember 2 turns of the crank for a 4 cycle motor so make sure its on the compression stroke. Easy way to determine it right now is that the rotor should be pointing to the wire that you have going to # 1 right now. If you are going to do this I would pull all the wires. The wire for #1 will now be the shortest one and go from there to match the correct lengths to each cyl. Hope this helps.

 

[Jeff73Mach1]

or you could mark the current #1 spot on the cap with a sharpie if you otherwise have good wire fit and leave it alone. It doesn't hurt a thing for it to be the way it is. Yes pulling and reinstalling the distributor is possible, but complications can occur and when they do, they can be a pain in the ass.

If the wire lengths are good as is, I would leave it alone after marking the cap.

 

[jbojo]

or you could mark the current #1 spot on the cap with a sharpie if you otherwise have good wire fit and leave it alone. It doesn't hurt a thing for it to be the way it is. Yes pulling and reinstalling the distributor is possible, but complications can occur and when they do, they can be a pain in the ass.

If the wire lengths are good as is, I would leave it alone after marking the cap.

+1

Yeah I totally agree. I would just leave it as is since it's running just fine.

 

[will e]

How about a couple of pictures of the cap and where the wires are going?

 

[ccijwright]

How about a couple of pictures of the cap and where the wires are going?

ok, I will take some tonight. Thanks-

 

[Don C]

or you could mark the current #1 spot on the cap with a sharpie if you otherwise have good wire fit and leave it alone. It doesn't hurt a thing for it to be the way it is. Yes pulling and reinstalling the distributor is possible, but complications can occur and when they do, they can be a pain in the ass.

If the wire lengths are good as is, I would leave it alone after marking the cap.

+1

Yeah I totally agree. I would just leave it as is since it's running just fine.

+2 - Another forum member had a "mechanic" install a new distributor, the guy pulled the oil pump shaft out of position at the same time, didn't get it re-installed correctly, led to the other member having to tear his engine down. As somebody else suggested, just use a marker and re-label the wire locations where the currently are.

 

[trainey]

or you could mark the current #1 spot on the cap with a sharpie if you otherwise have good wire fit and leave it alone. It doesn't hurt a thing for it to be the way it is. Yes pulling and reinstalling the distributor is possible, but complications can occur and when they do, they can be a pain in the ass.

If the wire lengths are good as is, I would leave it alone after marking the cap.

+1

Yeah I totally agree. I would just leave it as is since it's running just fine.

+2 Unless you have some other reason for pulling it. Maybe check your timing and let it be.

 

[Mikes73]

If it aint broke don't fix it til it is, I only suggested a restab because I assumed he was going to have the distributor out for some reason.

 

[Jeff73Mach1]

I'm just lazy and working hard to indoctrinate all of you into my way of thinking.

 

[CZ-75]

I'm just lazy and working hard to indoctrinate all of you into my way of thinking.

If you want to know the quickest, easiest, and in most cases, the best way, to do something... Ask a lazy person how to do it.::thumb::

 

[JimNiki]

That reminded me of an falcon xr I had decades ago. It had a 351w in it with a Mallory 289 cam. The timing was different. I always had to be aware of that when tuning because the timing specs on the manifold were incorrect in my case.