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Discussion Starter #1
Here's the facts 73 GTV, SPICA, All new igniton componenets ( Coil, wires, dist. cap, plugs) on a crane igntion thats about 5 years old. Spark on #1 cylinder seems weak and after 50 miles or so starts too mis fire. Plug is darker than the others and a bit fouled with gas.
Is there some way to check th intensity of the charge coming through the wire so I can see if this is just my imagination? Also what is the consensus on the best plugs to use. I have NGK BE5's in it now.

Otherwise the car runs very well....
 

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If you suspect the plug wire, try swapping it with another cylinder and see if the problem follows the wire (clean all the plugs first). Also, open the hood at night and see if you can see any arcing with the motor at about 2,500 rpm.

I like golden lodge plugs myself...
 

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1) How do you know it is #1 that is missing? Sure, that plug is a different color, but how do you know it is misfiring? Could all four be missing due to a problem with the Spica?

2) If everything in the ignition is new, then it is likely to be something else:

2a) Have you checked the compression when the engine is hot (i.e., has run > 50 miles) ?

2b) If the compression checks OK, I would suspect something in the fuel system. The Spica cars that I owned were famous for developing vapor lock once the car was fully warmed up. Is it worse with your fuel tank < 1/2 full? Worse on hot days than cold evenings? Have your fuel filters been serviced as thoroughly as your ignition system?

I know the "Spica huggers" are going to flame me for this, but I'd suggest ripping out the Spica and installing Webers (purely as a diagnostic, of course).
 

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I run NGK BP7es, on mine. It could be a coil going bad, could be a bad plug, wire, both or yes the spica. Since the plug is wet, it sounds like its going way rich and fouling the plug. If its only doing it on one cylinder, I'd chase the electrical gremlin first.

Will
 

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You can use an Ohm meter to check the plug wires for excessive resistence.
Snap-On also has a simple tester: http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=72523&group_ID=1352&store=snapon-store&dir=catalog .

As for plugs, like Will I find that NGKs work well in my 2L. NGK has a helpful website here: http://www.ngksparkplugs.com/part_finder/car_truck_suv/results.asp?engineid=282 . Their plug selector calls for BP7ES plugs gapped at .025". I use B7ES plugs gapped at .030" (electronic ignition). With bigger valves, the projected tip plugs (BP7ES) don't allow much clearance.

The plugs you're using are two stages hotter than recommended ( http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf ). Was your engine fouling the plugs before you went hotter?
 

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Any time I have a misfire on a car with a Crane ignition, especially a misfire that gets worse as the car warms up, the first thing I do is verify that the optical trigger is phased properly. What I mean is that I make sure that the trigger is signaling the coil to fire when the rotor is centered on the contact point on the distributor cap.

Because these Crane ignitions are generic units with the trigger on a sliding bracket, this is not a given. I've experienced this problem with a number of cars that have Crane ignitions. Sometimes, a new set of plug wires will make it more noticable because some newer sets of plug wires currently in the supply chain have higher resistance than older and/or original sets. Sometimes, one cylinder will miss worse than some of the others because its plug wire is closer to a groud source.

When a Crane unit is out of phase, the car runs OK when cold because the spark is able to jump the gap between the rotor & the contact point on the distributor. However, as heat increases, so does resistance. Therefore, as the car warms up, you develop a misfire.

The best way to check for this is to drill a hole in your old distributor cap (if you still have it) just inside of & directly in-line with one of the plug wire posts. Install this distributor cap on the car, & hook up a timing light to the plug wire that corresponds to where you drilled the hole. Then, with the car running, put the timing light to that hole. If the optical trigger is phased correctly, you will see the rotor pointed right at that post on the distributor cap. If it's even a little off center, the the optical trigger is not phased properly, & you have found your problem.

I belelive Crane's web site has all of this information, as well as directions for phasing in the trigger correctly should you find it necessary to do so. It's one of those tasks that is quite simple to perform yet for some reason requires an overly lengthy explanation.

If you do have to adjust the phasing of the trigger, this will most likely affect ignition timing; so you will have to check & possibly adjust ignition timing after you have the trigger phased properly.
 

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Discussion Starter #7
Thanks, I'll check that

Thanks for the good info on crane igntions. I will check that this weekend. Sounds probable since everything else on the car has been checked and is AOK
 

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As a point of observation, I would check the distributor cap itself to see if there is a bad contact inside of the cap itself. Check the contact gap to see if there is erosion on the rotor and contact inside the cap. High energy ignitions eat caps and rotors. Sometimes corrosion inside of the cap where the wire plugs in will cause a problem. Ignition rotors with resistors can give problems. All good advice for things to check being posted by all.
 

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Discussion Starter #9
I think M. Keith got it right

I checked the phasing of the distributor and it was way off. Hard to understand how it ever ran really.

Thanks again Mike
 
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