This is likely more obvious than I think but here goes. With so many plugs made for the T, I have observed a great variation in length of lower porcelain, length of exposed electrode, etc. This varies considerably even among different vintages of Champion X plugs.
My questions:
1. What are the characteristics that are visible if several plugs are compared to indicate the RELATIVE heat range differences? The longer porcelain runs cooler? Hotter?
2. What is the chance a hotter running plug would be of any benefit running in cylinder #1?
The more insulator showing means the plug is hotter.
If your #2 plug is fouling you need to figure out what is wrong with that cylinder that is causing the fouled plug. Maybe a bad coil box connection? Worn out piston rings? leaking valves?
What are the symptoms? Is it oil fouled or fuel fouled?
There should be no reason to use multiple heat range plugs in one engine.
Royce, mostly I was wondering about the plug variations. My engine has only the minor sootyness (no oil foul) of #1 compared to the other three, which I consider normal for a T, so question #2 was mostly an afterthought.
So longer insulator, with less center electrode exposed = hotter plug.
Question 3. Why the variation over the years from Champion?
So is the Champion X plug a mid-hot or a hot plug?
Are the motorcraft modern T plugs considered to be as hot as a Champion X?
From what I read on this forum over the years hot plug is best for a T engine.
#1 running colder than the others has been fought by a lot of T owners, who have come up with various gizmos, and by heat shields such as these:
OR, you could just install a thermostat, and save your engine from running too cool most of the year.
rdr
None of that garbage is necessary if you car runs right.
I've been using the same set of Champion X plugs in my 15 through the last ten years since the last engine rebuild and they were just cleaned with gas between rebuilds, so they might have 20,000 miles on them since I bought them used. No telling how many tens of thousands of miles they went before I got them.
I don't know why Champion changed the design over the years but all of them seem to work fine. As long as the porcelain is not cracked and the electrode still has proper gap use them.
Hey !!! I made the Ralph/Royce Hall of Shame. How COOL is that <grin>
Be_Zero_Be
The insulator and electrode conduct heat away from the tip of the plug. The smaller the diameter of the insulator and the longer the path to the plug body,the hotter the plug is.
So, The ultimate question that this thread leads to (for those that don't have a new Champion A25, Champion X, Motorcraft, or Autolite plug to lay side by side and compare insulators and electrodes) is how do the currently half inch pipe thread plugs compare in heat range? I won't even ask about the dozens of 14mm plugs that could be used with adapters.
Terry,
Use what you have and don't worry about it.
Ted