Can anyone tell me why the left plug has an extension beyond the threads at the bottom and the one on the right does not?
Someone said one would be for a hit-and-miss engine and the other for a Model T. If so, which is which?
Thanks.
I'm running all OLD, NOS, X plugs like the one at the left.
Most hit & miss engines have enough room between the head and piston to put a sparkplug INSIDE the cylinder.
Caution, I'm no expert.
As far as I know, the type on the right are older than the type on the left. Only a matter of vintage, but they are the same plug and both work for the model T.
Would love to hear more detail from someone who knows. Seems this has come up in the past.
The typical Ford X is long length to reach the combustion chamber, early ones were shorter when the low head was used. With the later high head, the longer plug is better.
1918 ad.
Ford script Champion X in high head cutaway showing the plug depth needed for the electrode to give the best fire to the T. Factory recommended plug.
Here is an ad showing that both "long" and "short" were offered at the same time:
In Dan's first picture the plug on the far right, without ridges in the porcelain, is the type used up to the early twenties. There's a version which came after it, not shown, which had ridges like the later plugs, but was like the earlier plug otherwise. The center post, which was removable, had a 6-40 thread. If I was at home I'd show a picture of it. All the later plugs, from the later twenties on, have a non-removable center post attached by the crimped-on brass cap. The thread on these plugs is 8-32.
Might anyone be in a position to comment on what spark plug was installed in a Model K Ford from the factory?
I am not an expert but I bet that the K was supplied with Splitdorf plugs.
Paul - thanks for the reply. Might you happen to have a picture of said Splitdorf plugs? Timothy
The Splitdorf are very pretty green, you can find them for a few bucks at swaps. Good to add to your 1/2" pipe plug collection for your T
Ford used Soot Proof plugs on the early Model T. Maybe on the K also?
Here's a set I have....
Now that I'm home I can show that late/early X with the ribbed insulator, and a couple of views of the Wards version. Not as nice as William's set, but OK for three bucks.