AC W, is the long plug for Hudson and some Essex engines. It is a hotter plug similar to the Champion D21 while the D 23 is the hottest then available.
Be careful, there is a little newer AC plug labeled AC W but is a very cold plug - physicaly shorter and with a side pin for racing service. there are some on ebay
Other plugs with a long reach are Champion 9Com ( Com for commercial) AC 88L-Com Autolite B11
There was a plug put out especially for David Brown tractors which were champion 7-Com-L, with two ground electrodes. I bought four sets in 1960, and have used these for 60 years, still have one set left! I'll be 120 years old by the time I have used the last set! If you are going to change to long reach plugs you will have to run a tap down the threads to clean out the carbon, and you must check that the plug will not extend beyond the threads. If they do two things can happen, the valves will hit the plugs, and the plug threads that are exposed will carbon up and you will not be able to remove them.
I run the Champion D21 in my car with great success.
I’m not sure how much longer of a plug you want run. but do know that running a plug longer than originally equipped with from the factory is also like adding timing to the engine as the flame front is started deeper in the combustion chamber.
just my experience from working on race cars for a living. It may have little effect on a engine with such low Compression.
Comments
Be careful, there is a little newer AC plug labeled AC W but is a very cold plug - physicaly shorter and with a side pin for racing service. there are some on ebay
Other plugs with a long reach are Champion 9Com ( Com for commercial)
AC 88L-Com
Autolite B11
If you are going to change to long reach plugs you will have to run a tap down the threads to clean out the carbon, and you must check that the plug will not extend beyond the threads. If they do two things can happen, the valves will hit the plugs, and the plug threads that are exposed will carbon up and you will not be able to remove them.
I’m not sure how much longer of a plug you want run. but do know that running a plug longer than originally equipped with from the factory is also like adding timing to the engine as the flame front is started deeper in the combustion chamber.
just my experience from working on race cars for a living.
It may have little effect on a engine with such low Compression.
John