Hey all,

As I continue to work out the gremlins on my newly bought 66 f100, I noticed the distributor cap spark plug wire location is different than what should be.

Truck starts and runs fine.

But as I know it, spark plug wire #1 should be where #5 is with the firing order continuing from there, counter clockwise.

Like I say the firing order of the wires on the cap are correct, but in different locations.

Anyone take a guess on why?

 

If an engine is put on TDC on the compression stroke you can put a gear driven dizzy in any position you want. Make #1 where the rotor points and continue in firing order in the direction of rotation and it will run just fine. 4 positions for a 4 cyl, 6 for 6 cyl, 8 for an 8cyl. The last person to put your dizzy in wasn't concerned about the position of the dizzy housing or where #1 was located.

Now a lot of OE Ford and some replacement dizzy caps had a 1 molded into the cap and that was either side of a cap hold down clip. My books show # 1 where your #5 is.

If you choose to change your position to the book/stock location. Remember the drive gear is on an angle and it will not always drop all the way in, to engage the oil pump. With housing where you want it and rotor slightly away from your choice position, you need to turn the engine a little forward or back to let the dizzy drop all way in, move engine back to TDC. With dizzy all way down and you miss your target cap location, lift dizzy and move 1 tooth in direction you need and do the procedure again to engage oil pump.

 

^^^ What he said. It can be a real pain to get the rotor lined up to #1, sometimes people just "stab" the distributor anywhere and then install the wires on the cap to suit. The distributor doesn't care.

If you want to use a timing light though, take care to note where the "#1" piston wire now is. If you connected the light to the "#1" as listed on the cap, the timing marks wouldn't make any sense, would they?

Also it depends on the engine but, sometimes the housing will not physically rotate far enough to advance enough ignition timing in depending on how it was installed. So long as there is plenty of range of adjustment e.g. the vac advance can doesn't hit the intake or something, it won't matter and you could leave it if you wanted, unless you're OCD, and will have to make it right. Just don't drop the oil pump rod down into the crankcase, etc.

 

Thank you for the answers.

Yes, there is a #1 stamped on the cap but #5 is in its place.

As long as the firing order is correct, I'm not concerned with the wires "correct" locations.

When I switch to a four barrel carb and intake I will correct it all then.

Thanks again,
Aaron

 

Obviously timing light is best route to go; however, when I am looking for a quick check to determine if I am in the ball park of TDC, I remove #1 spark plug, with the ignition off, place my finger in the opening and immediately stop when compression forces my finger from the opening. Then compare rotor location with timing mark. From pic it appears close; if off, lift dizzy and rotate to desired location, same time, I would try and position the vac. advance module to the center so I could retard, or advance as needed.

Seems to me, if the vac. advance was rotated to center position may be getting close to the correct position, may need to rotate distributor counter clockwise a bit, assuming of course the cam and crankshaft timing marks were installed correctly, or have not slipped?

 

My timing light is not doing me any good at the moment, the crank pulley/balancer have no marks.

I have removed, cleaned and sanded every inch of the pulley/balancer, nothing.

On my list is to TDC #1 cylinder through the spark plug hole so I can mark the pulley and have something to go by.

 

The 65 F100 which has the 64 Thunderbird 390, has been setting in the elements for the past 7 plus years and the pulley markings are rusted over the timing marker is missing. As I mentioned #5, using a vacuum gauge (18-22) hg, then I fine tune once the engine is running; keeping in mind, any adjustment in idle mixture requires readjusting the timing and vice versa.

 

Is that an International Harvester distributor cap with studs not pockets.
Just what I have been looking for. Thanks