spark plug gap

Jim/GA said:
0.035"

.
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Jim, I respect you as one of the most knowledgeable guys in the hobby, but I would like to offer an alternative to your recommendation based on personal experience.

It is true that the Service Bulletins settled on .035 in Feb 1931, and that has been the accepted standard for 90 years. But as a counterpoint, I’ve worked on and played with these cars since 1961, and my first engine rebuild was done by Lou Hanel about 1965. Lou was a pioneer and a legend in NW Model A engine rebuilding, whose experience went back to about 1940. If you had a Lou Hanel engine, it was known as the best you could get.

Lou has been gone now for about 25 years, but I still have his instructions for engine breakin, in which he says plugs should be gapped at .032. I have set mine mostly to his specs Since 1961, and that has served me well, owning about twenty Model A’s over that period, and driving well over 50,000 miles total in restored and unrestored cars. I have used both .032 and 035 gaps in my plugs, which currently are Champion 3X, but I haven’t noticed a significant difference either way.

So I am not trying to contradict you or the Ford Service Bulletins. I’m just sharing my experience, for what it’s worth. :rolleyes: Next time I set my plugs, I’ll try .035.
 
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keyswitch1 said:
What gap should they be set at ?? Thank you !!
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People are recommending a stock gap size for you, and that's good.

If you have a stock ignition system and engine, then that spec is fine.
The system is also forgiving in that if you change the gap slightly, nothing bad will happen.

Its also true that many folks on this forum run their gaps larger, .040 or .045 maybe. These folks may have a stronger coil compared to the weaker Ford coil, or other modifications that result in a stronger spark.

The point is, when you ask what your gap size should be, its also important to state what type of ignition system you have. Ford parts vs repop vs high performance, fairly new vs 90 years old, 6v vs 12v, electronic vs mechanical, and so on.

There is no doubt that you will get several different answers because folks have had plenty of varying experience working on these cars.
 
1930-Pichup and duke36 are right, of course. I have always run my cars strictly stock, which reflects my comment above.

Hey Purdy! How are things in Alabam?
 
I run higher compression heads on some of mine . I run and have good results with a spark plug gap of thirty five thousands on all of them .
 
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