spark plug heat ranges
#1528624
11/04/13 06:33 PM
11/04/13 06:33 PM
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California
mickm
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i don't really understand the concept of heat range in plugs. it's basically the height of the insulator that determines heat range, correct?
so how does that work, and how do you go about finding the right range for an engine?
Last edited by mickm; 11/04/13 06:33 PM.
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Re: spark plug heat ranges
[Re: mickm]
#1528625
11/04/13 06:40 PM
11/04/13 06:40 PM
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Posts: 4,330
Lynchburg, VA
Leon441
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The hotter the plug the more heat the plug retains during firing cycles. So if a plug is too hot for your application it retains too much heat between firing cycles and pre detonates and also can get too hot and break down. Too cold a plug and it misfires due to not holding enough heat like a cold engine.
Others can elaborate on the subject a little better.
Leon
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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Re: spark plug heat ranges
[Re: Leon441]
#1528626
11/04/13 07:04 PM
11/04/13 07:04 PM
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TN
SCATPACK 1
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Does not necessarily have to be an extended tip plug. It is based on the amount of space between the porcelain insulator and the metal part of the plug. The more air between the porcelain and the metal, the hotter the plug is. I can't get any pictures to post or I would attach an example. Dick Landy recommended to run a J-12 on his engine for street driving and a J-62 or J-63 for when he was Racing. A J-12 Champion is a hotter plug than a J-10 plug and will burn any oil that gets by the rings or valve seals better than a colder plug would. J-63 is a Champion Racing plug and is hotter than a J-62. A cooler plug will not misfire in a lean engine as easily as the hotter plug will. Sox & Martin used to have a Champion add that said they tuned their car by changing heat range instead of carb jets. (I think that is what I remember. LOL)
Old Geezer Racing
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Re: spark plug heat ranges
[Re: mickm]
#1528627
11/04/13 07:35 PM
11/04/13 07:35 PM
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How does it run when you run it thru the gears with max RPM? Does it miss any or is it smooth. Notice any smoke or color out the tail pipes? At idle, does it occasionally have a hick up or a miss?
How do your plugs look now? Are they smoked up after a run or shiny or slick looking or are they powder white. If it is dark colored and looks a little sooty or has a slick (oily)appearance on the porcelain, you may want to go one or 2 steps hotter. But if the porcelain is powder white and looks like it just came out of the wrapper, then you may want to go a step or 2 colder. Or tighten up the plug gap a little.
Hope this helps some.
Old Geezer Racing
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Re: spark plug heat ranges
[Re: rck850]
#1528629
11/04/13 07:52 PM
11/04/13 07:52 PM
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Rod
You were probably a little too rich at idle or may be you had some oil blow by or a combination of both. The hotter plug was able to burn off the excess fuel and/or oil. If you were to lean it out a jet size or two, then you could probably switch back to the colder plugs. OR Not. Leave it alone if it is running better now with the hotter plug in it. One other thing you might try if you drive it in colder weather, open the spark plug gap up another 5 thousands and it will burn a little hotter with the same plugs as before.
Old Geezer Racing
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Re: spark plug heat ranges
[Re: SCATPACK 1]
#1528630
11/04/13 08:05 PM
11/04/13 08:05 PM
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California
mickm
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Quote:
How does it run when you run it thru the gears with max RPM? Does it miss any or is it smooth. Notice any smoke or color out the tail pipes? At idle, does it occasionally have a hick up or a miss?
How do your plugs look now? Are they smoked up after a run or shiny or slick looking or are they powder white. If it is dark colored and looks a little sooty or has a slick (oily)appearance on the porcelain, you may want to go one or 2 steps hotter. But if the porcelain is powder white and looks like it just came out of the wrapper, then you may want to go a step or 2 colder. Or tighten up the plug gap a little.
Hope this helps some.
just getting through the MSD issues which were keeping this thing missing like crazy up towards where the rev limiter was set, so until i get a good box in there i won't know for sure, but typically the plugs are a little dark and sooty, so i will try hotter and see how it goes. 
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Re: spark plug heat ranges
[Re: Cab_Burge]
#1528633
11/06/13 04:22 PM
11/06/13 04:22 PM
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California
mickm
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Quote:
I would get the other tuning issues resolved first and then look at leaning down the idle circuit on the carbs. first and then possibly leaning down the part throttle cruise mixture next before changing the heat range on ths spark plugs, unless you are running a real cold drag race plug now  What spark plug brand and part numbers are you running now and how much ignition timing total? What is the compression ratio? One heat range hotter in my old family I/O ski boat would make the low compression pump gas motor ping  
NGK 6BPES
32 degrees total
~10.25:1 aluminum heads
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Re: spark plug heat ranges
[Re: mickm]
#1528636
11/07/13 01:39 AM
11/07/13 01:39 AM
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Joined: Aug 2003
Posts: 43,311
Bend,OR USA
Cab_Burge
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I Win
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Quote:
Quote:
I would get the other tuning issues resolved first and then look at leaning down the idle circuit on the carbs. first and then possibly leaning down the part throttle cruise mixture next before changing the heat range on ths spark plugs, unless you are running a real cold drag race plug now What spark plug brand and part numbers are you running now and how much ignition timing total? What is the compression ratio? One heat range hotter in my old family I/O ski boat would make the low compression pump gas motor ping
NGK 6BPES
32 degrees total
~10.25:1 aluminum heads
I don't think I would put the next hotter,5BPES, NGK plug in that(if it was mine) motor, I would try leaning down the idle first and then maybe the main jet down 1 or 2 sizes to help clean the NGK #6 plugs up BTW, is that a retracted gap or protruded gap?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: spark plug heat ranges
[Re: Cab_Burge]
#1528637
11/07/13 04:40 PM
11/07/13 04:40 PM
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California
mickm
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Quote:
I don't think I would put the next hotter,5BPES, NGK plug in that(if it was mine) motor, I would try leaning down the idle first and then maybe the main jet down 1 or 2 sizes to help clean the NGK #6 plugs up BTW, is that a retracted gap or protruded gap?
i assume protruded, in that the electrode is beyond the end of the plug? is that what that means?
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Re: spark plug heat ranges
[Re: mickm]
#1528638
11/07/13 09:10 PM
11/07/13 09:10 PM
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Joined: Aug 2003
Posts: 43,311
Bend,OR USA
Cab_Burge
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Quote:
Quote:
I don't think I would put the next hotter,5BPES, NGK plug in that(if it was mine) motor, I would try leaning down the idle first and then maybe the main jet down 1 or 2 sizes to help clean the NGK #6 plugs up BTW, is that a retracted gap or protruded gap?
i assume protruded, in that the electrode is beyond the end of the plug? is that what that means?
The protruded, AKA projected gap spark plugs, have the gap extended into the combustion chamber. The retracted gap do not, there is a side gap also where the ground electrode is inserted through the side of the spark plug body, commonally used in blwon motors. I don't have any of them to take a picture of Take a look at the two plugs in the picture, the one on the left has a protruded or projected center elctrode and ground strap, the one on the right(facing the plugs) is a retracted gap  IHTHs
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: spark plug heat ranges
[Re: Cab_Burge]
#1528641
11/08/13 07:32 PM
11/08/13 07:32 PM
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California
mickm
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Quote:
Quote:
i'll have to take a look, but i think the ones i'm using would fall under protruded.
Those work well in Hemi motors Unless you have a really high dome in them then the retracted gaps is the only way to clear the tall domes
no, don't have a high dome. 10.25:1, not high.
looks like i'm good with these, or i may give the 5's a try and see how they work.
thanks!
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