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I ran 40-50k miles on my autolite plugs with an MSD 6A. When I pulled the plugs today I found the center electrode pointed on all plugs. Why did that happen?
You can clearly see how the center electrode is pointed, no longer flat.
Edit: I found this online: Appearance & Symptoms: The insulator will have a glazed white appearance and may have small black deposits. There may also be abnormal electrode wear, and you will likely notice a loss of power at high speeds or under high engine load.
Possible Causes: Overheating may occur from over-advanced ignition timing, poor cooling system efficiency, lean air/fuel mixture, vacuum leak, or wrong spark plug heat range (too low).
So, I am using a stock plug for 78 ford 300. I have raised the compression, and nearly doubled the oem horse power. On top of that I'm running much more volts through the ignition system than stock, ...but still using the oem plug. What plug should I be using?
It is a stock plug, stock heat range, for a 78 with a 300. I run a DS2 with MSD 6A, 8.2 Taylor wires (now 8.5 msd wires), an MSD Street blaster TFI Coil (now Summit beefy coil with 48k volts), and .055 gap.
Should I run plugs with a higher heat range?
That is interesting you mention the plugs lasting only 10k miles. That is about how long my cap and rotor last. But they are under warranty, so I simply swap them for new 1 or 2 times a year.
I may try some diff. plugs. Is there something I should know about the numbers, heat ranges, etc?
Edit: oops, forgot to mention I have a fairly aggressive advance curve. Iirc, the guy said to run 16* initial advance (I run 10*), and that it was all in by 1600 rpm.
It is a stock plug, stock heat range, for a 78 with a 300. I run a DS2 with MSD 6A, 8.2 Taylor wires (now 8.5 msd wires), an MSD Street blaster TFI Coil (now Summit beefy coil with 48k volts), and .055 gap.
Should I run plugs with a higher heat range?
That is interesting you mention the plugs lasting only 10k miles. That is about how long my cap and rotor last. But they are under warranty, so I simply swap them for new 1 or 2 times a year.
I may try some diff. plugs. Is there something I should know about the numbers, heat ranges, etc?
Edit: oops, forgot to mention I have a fairly aggressive advance curve. Iirc, the guy said to run 16* initial advance (I run 10*), and that it was all in by 1600 rpm.
You want to go one step colder (plugs) on a street engine. Gap is good. How is your fuel curve?
You have a wide bowl DSII cap and rotor correct? MSD or FORD?
That is one aggressive dist curve. How does she do?
Actually, with all that IGN, 40K to 50K should be somewhat normal.(MOTORCRAFT plugs IMO). You should pull one every so often to see how they are burning.
I would agree that a colder plug is suggested for racing engines as in high compression and advance, or even stock engines seeing extended highway use in the summertime. Keep in mind heat range has nothing to do with spark temperature, has to do with the length of the insulator and consequently how fast heat is conducted out of the plug. Ideally be just hot enough to burn off deposits though no more.
I'm wondering if you noticed an enlargement of the gap from when you installed them to when you removed them. (And how much?)
"Wear" often erodes both electrodes without the center electrode tapering occurring.
While no one (including me) seems to have a clear explanation of the exact mechanism of the tapering of the center electrode, I would like to say that some plug manufacturers purposefully taper their center electrodes, probably to help them fire at lower voltages.
As far as heat ranges go, individual operating circumstances will govern your choice to a great degree. I usually try to choose the coolest one that doesn't foul. That way I stay further away from pre-ignition possibilities.
