Choosing the right plug...
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Elder User
Joined: Oct 2003
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From: Harrisburg, SD
Choosing the right plug...
I am in the middle of a 514 build. P51 heads, Roller cam, forged scat internals, DSS main support, all the good stuff... Anyway i have always used motorcraft or autolites before (relatively stock engines though) How do I decide if I need to run a hotter or colder plug? Im crowding 11:1, im not sure where to start is there a general rule of thumb then just trial and error?
Post Fiend
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I like the sound of 11:1, takes me back many years. However as far as plugs go all I can say is that the more severe the operating conditions the cooler the plug you need. Too hot a plug can cause premature ignition, something you do not want. Too cold a plug will tend to oil up. I would think you need to start with a cooler than stock plug for your engine, if they oil up go a tad hotter. Just my two pennies.
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Joined: Feb 2008
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From: Yelm washington
How do I know which is hotter and which is cooler??? (( sorry just a question that I have)) the truck i have right now has stock plugs and i bought bosch platinum+2s for it since Bosh platinum seems to work in my civic better than the stocks.
Posting Guru
Joined: Jan 2006
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From: Malvern, Ohio
Originally Posted by 93fordflareside351
How do I know which is hotter and which is cooler??? (( sorry just a question that I have)) the truck i have right now has stock plugs and i bought bosch platinum+2s for it since Bosh platinum seems to work in my civic better than the stocks.
More questions you ask = more you learn/know.
Posting Guru
Joined: Jan 2006
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From: Malvern, Ohio
Heck, I think I might have something in my parts books, but I am not 100% sure on that but if you like I could check for ya?
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Post Fiend
Joined: Jan 2005
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I would go with the stock plugs for initial startup and for breaking in. Get a set a couple of ranges cooler for when you are going to let it all hang out. The store where you get the plugs should have a heat range chart or, more than likely, the manufacturer will have it on their website.