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Discussion Starter #1
Thanks for the previous tips to check the firing order but it's wired correctly. Here's is my follow up thought and question:

I'm still learning about all this... but would I need to adjust the timing because of the bigger cap?

I may not be thinking clearly right now because of sun exposure and frustration but since the cap diameter is larger than what was originally there, therefore the terminals are slighly more spaced apart and the new rotor is slighly longer.... which would mean that all else being the same, the rotor is travelling at the same speed and the timing is set to fire at that rate for the shorter rotor, but tip of the rotor is now travelling a longer distance around the circumference and therefore take longer, right?

So.. because of all that, wouldn't I have to reset the timing to correct for the misfires? Man, I hope I made myself understandable. An analogy would be like changing the size of the tires and the effect the tire size would have on the speedometer. The smaller tire would make the speedometer read faster than what the actual speed was and a larger tire would make the speedometer read slower than the actual speed. Wouldn't this also hold true for the distributor cap or am I not K.I.S.S-ing this and over thinking the whole thing?

I have a headache.....
 

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You are over thinking the cap thing.Large or small cap makes no difference.The spacing of the terminals is the same...45 deg's(assuming it's an 8 cyl).The rotor makes the trip around the cap(360 deg's)in the same amount of time.
Checking the timming is a good idea any time a cap,rotor or points are changed.Did you check the inside of the cap for carbon tracks?(A pencel line can really F**K with a mechanic...been on both ends of that gag).Also check the rotor for a hole through to the shaft.
What kind of miss is it?Dead miss,intermitant,only unde a load?
 

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Easier way to think about this is: The distributor is gear driven. You didn't change the number of teeth on the gear, so, no matter what you do, it will still turn at the same rate that is was before....
Maybe the way you have routed the wires across the cap, they are missfiring from one plug wire to another plug wire.
The timing should not have changed to any great degree, unless you moved the distributor as you were installing the new cap....
 

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Discussion Starter #5
There's no hole from the rotor to the shaft. Is there supposed to be?

Well, it's a dead on miss. As soon as I turn over the engine, I get misfires and it misses at idle too.
 

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Discussion Starter #6
The new cap isn't dramatically bigger. The PO had what looked like an Accel cap on the Mallory ditributor with the female ends on it. I swapped out wires to Motorsport wires that needed the spark plug type terminals. So, I called up Mallory and told them what type of cap I needed for their Unilite distributor and they gave me the model numbers for everything I needed to swap back. So, comparing the caps, the new cap has a larger diameter.
 

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The idea of the larger cap is to separate the electrodes by greater distance and hence create a more difficult path for electrons to flash over to another terminal. As long as the cap (and rotor) fits and is in good condition it should be okay.

To check for flashover, park car in dark garage, remove rotor, tip cap over on its side, so you can see inside the cap. Crank engine with someone observing the inside of the cap (Don't hold it in your hands). If you see any flashover then the cap is bad. Reason: the insulation on the cap should block any spark between terminals. Note: all wires should be connected to the cap when this test is accomplished.

Next test if the above passes. Install rotor on shaft. Remove coil wire and hold it with a high voltage fuse holder (get at any Home Depot or Lowes). Hold the coil wire over the top of the rotor, about 1/4" away from the center contact. Have someone crank engine and watch for a spark. No spark should jump to the rotor! If it does, the rotor is bad. Reason, the insulator on the rotor should block the spark.
 

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Your analogy about the longer rotor having to cover a greater arc is true. However, since the rotor is a solid piece, the outer tip automatically moves faster. If it didn't, the rotor would have to have been made of a liquid and of course that wouldn't make sense.

I suggest opening the car hood and at night in a dark garage try running the engine and look for arcing wires.

When I was a kid the Honda dealer wanted $50 to rebuild the cylinder head on my Z50A mini-trail. That's how I discovered the arcing and a 99 cent spark plug connector solved the problem.
 

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I have a headache.....

Sometimes thinking too much will do that to you...*G*

Unless the cap is indexed wrong or the rotor is too small for the cap diameter, discount the cap. Some are made bad but this is rare. However....
From your original thread...
<blockquote><font class="small">In reply to:</font><hr>

What gets me even more is that I pulled everything off and reinstalled the old distributor cap, rotor, and wires and everything was running as it should.

<hr></blockquote>

You may have answered your own question...

I was going to say "typical for a Mallory Unilite" but I woulda been wrong, eh?? *G*
 
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