The Stovebolt Site Forums The Shop Area Engine Shop Plug wire position on distributor cap

Well, now I have a clean gas tank and the fuel lines, etc. have been flushed out. The engine seems to run OK, but no better. I'm sure that the carb needs rebuilding, and I want to go thru and set the valves and timing first. The one thing that I notice that seems odd, is the position of the plug wires on the cap. I thought that #1 plug wire would be the first wire "clockwise" from the back clip where the locating notch is. However, that place is occupied by the #4 wire.

I kinda think that the distributor may be in one tooth off, but would one of you 216 babbit pounder guys take a look and tell me how your wires are positioned? Thanks

[img]http://webpages.charter.net/fredstev/plugwires.jpg[/img]

fredstev,

This answer is not meant to be a joke or rude; other people have asked the same question. The #1 cylinder wire is the one the rotor points to when you have the #1 cylinder ready to fire (or, nearabouts ready to fire). The position of the rotor is dependent on how/where the rotor is positioned when the distributor is installed (and thus could be in any position).

Thus you start the firing order of the wires from wherever the rotor points when #1 is at top dead center to fire. This position can be tested by putting your finger over the #1 spark plug hole and you feel air pressure as the #1 piston comes up while you or someone else rotates the crankshaft pulley - both valves are closed when #1 fires).

If I'm wrong or if someone else can explain this better, we will hear about it.

Tim

By the way, if you resize your picture to 640x480, the picture is more easily viewable.

Sorry about that, I resized the picture. Anyway, yes, I understand that as long as #1 cylinder is at top dead center and the distributor rotor is under the wire going to #1 plug life is good. What I don't know is if it matters as far as the advance mechanism or point dwell and so forth. I don't think so, but I ain't sure. Most service manuals show a diagram of the distributor and the proper location of the plug wires. I always assumed that there was a reason for this.

Fredstev, No it does not matter for points or vacuum advance mechanism either. As long as you have accurately found TDC and attached the #1 plug wire to the post that the rotor is pointing to and then just attach the rest of the wires according to the firing order in the direction of rotor rotation (Clockwise I believe).

Clockwise is correct, cujo8. OK, I'll not worry about where the plug wires are on the cap. Thanks.

Unless the number of teeth on the dist. gear is a multiple of six, it does matter. As you know, it runs. However, in the right position, the rotor & cap terminal will be more closely aligned at the moment of firing. Any other position may be close enough for the spark to jump over & run, yes, but not right. Under high RPM or loading conditions, it can & probably will, experience 'spark scatter' or misfire, & you won't get the full power from your engine. Doug

it's always a good idea to mark where the #1 pot is located on the cap for future reference
gooday
jim

Your distributor body and vacuum advance are at the factory positions but #1 was directly over the coil wire from the factory. If a nitpicker you could fix that but it will not effect performance.

I'm not a mechanic but "common" sense tells me that if the # of teeth are not a multiple of 6, it will not work at all. By the same logic, the rotor and cap terminal spacing will be the same regardless of # 1 position around the circle if the timing is set correctly. Please explain.

Desertdog,

Rotary position has nothing to do with the # of teeth. If #1 is at top dead center, the rotor is pointing at #1, and the timing is set right it will run right.

That is to say: skip any number of teeth and rotate the Disty. the same ammount and you are back in time.

... and who says you can't turn back time?

tclederman,
You are 98% correct. If you hold your finger over #1 plug hole and feel air pressure, you must make sure no one has stuffed a potatoe up your tail pipe, otherwise you could be on the
exhaust stroke! Sorry, but you opened the Can-O-Worms.

Stuart.