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| | | | Joined: Jul 2010 Posts: 65 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 65 | Hi
My 1937 manual shows spark plug gap should be .040 although advice from members previously have suggested .035 - Which is correct, or is it that .035 is more suitable for todays spark plugs
Truck is stock still on 6 volts | | | | | Joined: Jan 2015 Posts: 914 'Bolter | | 'Bolter Joined: Jan 2015 Posts: 914 | You are not using modern plugs but the plug that your engine calls for.
My manuals show that your correct spark plug gap is .040"
And, your correct plug is AC - 46.
Last edited by 32vld; 06/26/2015 1:03 PM. Reason: spelling
| | | | | Joined: Aug 2005 Posts: 6,377 Ex Hall Monitor | | Ex Hall Monitor Joined: Aug 2005 Posts: 6,377 | <CLICK> It's handy to have a shop manual laying around. Repops are available.
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| | | | | Joined: Feb 2004 Posts: 29,776 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,776 | A .005" difference in plug gap might be noticeable on an oscilloscope pattern as a slightly higher firing voltage with the wider gap. A clean plug firing from a squared-off center electrode will fire at around 8K to 10K volts, and the average point-type ignition system can develop 20KV or more. Once the gap is bridged by the spark, the voltage cannot go any higher, so clean plugs are the best option, regardless of where the gap is set. I really doubt that a .005" change in plug gap will make a performance difference during normal driving.
HEI and other electronic ignition systems can benefit from a little wider plug gap because they have a 50KV or higher voltage capacity and a wide gap allows more voltage to build up before the gap is jumped.
Jerry
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