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Which plug would be better for Circle racing (Ford N head 351, circles 6500-7800 RPM) NGK B8EFS or Autolite AR474. Autolite has a race plug but the NGK B8EFS spark plug is not designated for racing, I"m sure its fine though. I read the last post about NGK being better but in this case there is not an NGK race plug for the newer N-heads. Thanks in advance Guys
The autolites will make a few more horsepower on the dyno.Just make sure the plug is cold enough.We've went colder and colder and never lost any hp. to hot can lead to detonation.
The Autolites will make a few more horses on the dyno? Totally wrong. Spark plugs Do Not make Horsepower. A worn or damaged plug can loose horsepower but gaining horsepower from one brand to the next is false.
ive been running the N heads since they came out, tried several different plugs, but always went back to good ole autolite 23s , these heads have a fast burn chamber so the colder 23s worked best for me at 28 degrees total timing, now im sure that some one will tell you they made great hp gains with e3,s or some other great new plug, and I like trying new thing as well, but all the way around, the 23s were fine for me,JMO,
oh by the way, indexing the plugs do make a difference