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I need to replace the spark plugs in my 73 351C-4V motor. Currently it has Motorcraft ASF-42C plugs in it. I've been looking at the Bosch Platinum and the Split-Fire plugs and wonder if there would be any advantage in using them as opposed to "regular" plugs. Obviously the Bosch Platinum should last longer than regular plugs but I was thinking more in terms of a performance advantage.
 

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Obviously the manufacturer wants us to believe there is an advantage. There may be, but I suspect not much in the RPM ranges an engine lives in for most normal day to day driving habits. I think standard plugs are just fine in those conditions.
 

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Don't waste your money on split fires.

Plain is good.

Slade
 

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Plain ol' Autolites work great for me in all my cars.
 

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IMHO, keep away from split fire, they are junk. It you want better performance from your spark plugs then install the plain plugs and change them more often. The advantage of Bosch Platinum plugs is that they last longer. I've seen advertisment that claim 10 HP increase with plug change alone on RICE but dyno testing in the mags can come up with maybe .5 HP increase and sometime loose HP. Good luck :)
 

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The platinum plugs last longer than the normal ones. This is how new cars can go 10K miles between tune-ups.

The split electrode really does nothing to help your car. You won't get two sparks, or if you do, they will not be as fat as the single electrode would get. The concept is that you get a spark to each of the multiple electrodes, which exposes more spark surface to the mixture. In reality, the electrodes are smaller, so they burn up faster. At least, that has been my experience.
 

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If the SplitFire concept is so great, then why haven't other manufacturers copied it? (Bosch did and ought to be embarrassed.)
 
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