Spark plug heat range.

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Doosterfy

Doosterfy

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I have a 440 with about 11.5 to 1 compression. The cranking pressure is 210 psi. I've been running it for over a year with Champion RC12YC plugs with no problems at all. I run 93 pump gas with Klotz KL628 octane booster and I'm not getting any pinging or dieseling when I shut it off and have not had any plugs foul at all. In fact I have had the same plugs in it since I first got it running. A fellow racer is insisting that I should go to a colder plug because of the compression ratio. Just wondering what anyone else's thought are on this. Seems to me that if its not pinging or fouling plugs I should not need colder plugs. Also I should mention it has 440 Source Stealth aluminum heads. Thanks in advance.
 
bOb shingler said:
isn't that plug a couple of steps cooler than a stock plug?
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IDK its the plugs that 440 source recommended. At this point I'm going to ignore the guy telling me to go colder. Its not pinging and not fouling plugs so as far as I'm concerned the heat range is correct.
 
If it works don't fix it. I like Autolite and Motorcraft plugs myself. Never had much luck with Champions in big blocks. Is this racer friend a local living at the same altitude etc?
 
mguner said:
If it works don't fix it. I like Autolite and Motorcraft plugs myself. Never had much luck with Champions in big blocks. Is this racer friend a local living at the same altitude etc?
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Yup, same thing I'm thinking. The guy races at the same track as me, Lebanon Valley Dragway, West Lebanon, NY. He claims he's a tuning expert and told me my car was slow for the parts into it and he even spent about an hour checking things over in the pits. One by one his theories crumbled as he checked it out. The reason the car was slow (mid 11s @ 116, best 11.48) is because I had the tiny Schumacher try-y headers and had not fine tuned it. The only tuning I had done was set the timing to 20 initial and 38 total and I have 78s in the front bowls and 82s in the rear on the carb. It ran quite well so I left it alone. I'm installing Pro Part full length headers right now along with an 02 gauge so I can fine tune it. Heading back to the track on Sep 26th for Mopars at the valley so I'll see how it does. And I drive it back and forth to the track 220 mile round trip.
 
If the top 3 threads of the plug are discolored, then that's about where you want to be with the heat range, so they say. Less discolored threads, too cold of a plug. More than 3 discolored, too hot of a plug.
 
Doosterfy said:
I'm installing Pro Part full length headers right now along with an 02 gauge so I can fine tune it.
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Be careful in giving 100% trust in these AFR gauges. I had mine set where I had 13.0 AFR at WOT because that's supposedly in the range you want to be in from what I read. You would have thought that was enough to give the plugs SOME sort of color. I was WRONG! I pulled the plugs and they were BONE WHITE. They looked like the car was running incomprehensibly lean. I ended up jumping 3 jets in the front and 2 in the rear to get it down to 12.0 AFR at WOT just to get into a safe zone to prevent detonation problems I was having. Don't get me wrong, they are a great tool to have for tuning purposes. I just wouldn't trust all the numbers you read that the AFR needs to be.
 
Trust what the engine is telling you.
Aluminum heads suck heat out of the chamber pretty good.
I have those same plugs in my Eddy-headed 360. They've been in there for well over 100,000miles. I bought a new set years ago, but when I pulled out the current ones, they looked so good, I screwed em back in; again and again..........
Not the same,I know, but ...........I trust the plugs.

BTW, I ran my street 360 at 205psi on 87E10 just fine at 34*power timing. Like said, aluminum pulls heat pretty good(bad). Ok, hard.
 
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