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Discussion Starter #1 (Edited)

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I never bother, and the NGKs have worked well in all three Alfas for years. I keep thinking that, within reason, precise plug gapping is overrated, but that's just my own experience.
 

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All other things being equal, iridium wire plugs can run with wider gaps. .040" is common in modern cars. My Spider runs better with them set at .050".
 

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Plug gap becomes important on coil on plug cars like 24v 164, when the coils start to age and the insulation starts to break down. One can coax another 25k mikes out of a partially failing coil by keeping the gap within spec
 
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My concern is some idiot had dropped the box the spark plug is in and its landed on the important end ...

Pete
 
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when new in the box, here in USA the business end of the plug is covered by a cardboard or plastic tube, to prevent damage from exactly what you describe. Always a good practice to check the insulator for cracks, for correct part number, to tighten up the top cap, and check the gap!
 

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Dropping a spark plug is unlikely to open the gap, in fact just the opposite.
 

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Dropping a spark plug is unlikely to open the gap, in fact just the opposite.
Correct, and that is why I check them, to make sure they are not too tight

Pete
 

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Generally speaking you want to run the widest gap that will consistently fire the mixture. Coil ignition require the narrower gap whereas fully electronic ignition will produce reliable sparks at very wide gaps. The higher the compression ratio ( or turbo pressure) the narrower the gap will need to be.

For OBDII engines if it isn't throwing a code it isn't misfiring. If it isn't misfiring the gap isn't too wide. By far the bigger problem is gaps too narrow. That differs from the old points fired coil ignition.
 

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@goats is correct. Too wide a gap can ruin coils. For my vintage cars, and farm equipment, I use the basic Champion copper plus spark plugs. Heck, the Alfa Owner's Manuals from the 60's-through the 90's included Champion part number-model numbers as accepted replacement plugs to whatever the engine was supplied with from new. No, they won't last 100k miles, but that's ok. They only cost $2-3 bucks.
 

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Discussion Starter #12
See what I've started lively discussion! As for Champion plugs I still run 415's in BB1 my 91 164 set at 0.025" and replace the oil fouling one in #6 cylinder quite often. They are one heat range hotter than original Champions called for in 91 owners and shop manual.
 

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Maybe old vintage coils but not good modern coils.
I completely disagree. Too wide a spark plug gap causes misfire codes, and ruins modern coil-on-plug coils across all platforms, makes and models. In my experience, it is the number one reason that coils fail on modern engines.
 

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As applied to Alfa Nord engines, particularly those with carburetors, widening the gap is likely to improve running and throttle response. I have posted results of these tests. The voltage required to start a spark in a stock motor with copper electrode plugs is about 12 KV. Many coils are rated at 40K to 60KV and there is plenty of margin with one of these coils to open up the gap. Additionally, fine wire electrode plugs, the ones that we are discussing in this thread, need less voltage to establish a spark. Read up on electric field theory if you don't understand.
I have been running an MSD Blaster coil with .050" plug gaps for many years with excellent results and no problems. My old Acura used .040" gaps and it went 110K miles between plug changes and it never had any ignition problems.
The problems that I see in ignition systems on Alfa's are multispark CD ignitions causing failure in rotors, caps and ignition wires.
 

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I completely disagree. Too wide a spark plug gap causes misfire codes, and ruins modern coil-on-plug coils across all platforms, makes and models. In my experience, it is the number one reason that coils fail on modern engines.
Yup. Overworking a coil heats it up. Heat kills coils sooner or later. Coil on plug are already vulnerable to heat sitting right on top of the plug they fire. When SAAB introduced their DI cassette system for four cylinders each coil sat in an oil bath. Failure mode almost always resulted from overheating of the failed coil. Two common causes: cracked oil reservoir leaking the cooling oil out or serious general overheating of the engine.
 

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Wow. Never even occurred that needed to check the gaps on these plugs. Suppose bit silly of me as have always checked gaps on cars prior to the 164. Going to buy some feeler gauges now.
 

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Discussion Starter #18
Wow. Never even occurred that needed to check the gaps on these plugs. Suppose bit silly of me as have always checked gaps on cars prior to the 164. Going to buy some feeler gauges now.
You don't use flat feeler gauges to check gap on plugs. The wire gauges are best to check gaps. spark plug gages - Bing
 

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