Spark plug gap after HEI upgrade...

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Addicted to Junk

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Hi all. I know it is probably sacrilegious but after many months of failing starts, I upgraded my ignition to a GM HEI style distributor. Turns and starts every time. It does run kind of questionable as far as being smooth running however. I just had the carb rebuilt as well. When I went to time it, it seemed to be all over the map. I was wondering if the issue is with spark plug gap. I am running Autolites in it as the local guy didn't have Champion, which I know these older 318s seem to prefer. I gapped them at the stock .035. As an old Chevy guy, it was common at add .10 to the gap if you switched from points to high energy, but not sure if this would be the same here. Anyone have any experience switching out their stock ignition have any thoughts?
 

dodge dude94

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I was always told that when switching to HEI you could run between .050 and .065 on your gaps.
 
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Addicted to Junk

Addicted to Junk

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Huh, well that's a surprise to me. I don't recall ever gapping anything over .45. At least stock anyway. I'll try it though. Sure can't hurt at this point. It'll also give me a chance to get some champions too. Thanks DodgeDude94!!
 

crazzywolfie

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most of my plugs were gapped at 0.050 when i recently pulled them and checked things and all had good color and i am just running stock ignition system
 

crazzywolfie

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after doing some research it may be best not to go too much larger than 0.045. any larger and it is possible the engine may become harder to start and not run as smooth especially when the plugs start to burn up and the gap opens up. i know 1 of the plugs that i pulled out of my engine was a platinum ngk plugs and i only had it in my truck for less than 5000km and the gap was larger than 0.035 that is should have been. i know your not suppose to gap platinum plug but i did anyways even tho i ended up pulling it and replacing them with NGK v-power plugs.
 
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