Champion W18 spark plug

B

Bookaray

Junior Member
I just installed Champion W18 plugs in my '28 Coupe. Should I set the spark gap at .025 as recommended by Champion, or .035 like the W16Y plugs I had been using? It is running well, but really hard to start.
 
It really doesn't matter. The closer the gap the less likely there is of a high [? in a Model A] speed misfire. Wider the idle may be a little smoother. But, it'll probably be hard to notice either.
 
Yes a too narrow gap will hinder sarting . I run mine with a gap of .035 . I wouldn't run any spark plug in any of my model A's with a gap less than .035 unless I had a coil going out and I had to close the gap so that a weak coil could jump the gap to get home. You may have a weak coil.
 
a narrower gap can create a weaker spark causing an incomplete burn. your better off at .035 for a stronger spark and a complete burn. to wide of a gap can cause a high speed misfire
 
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