Dispelling the NGK myth

It would seem that some believe the NGK TR6 spark plugs sit deeper in the combustion chamber than the autolites, due to the longer threaded area. I bought the NGK’s with this assumption; it made sense to me. I wanted to see how much deeper they sat in the cc, so I installed them on a spare set of 4V heads I have lying around. As it turned out, when fully installed they sat at EXACTLY the same place in the cc as the autolites that came out of the head. I was a bit confused at first since they shouldn’t bottom out for another 3/8". However, when I pulled it out I noticed that the hex head was in the same place on both plugs, and that area must be where the stop is.

The red arrow shows the additional threaded area of the NGK,
The green arrow shows the same position of the nut.

Any additional gains should be attributed to other areas, not the additional depth of the NGK plugs; it's non-existent.

http://mark8.org/users/Eli/1/NGK.jpg

RE: Dispelling the NGK myth

actually the stop that is used is the first flare right abouve the threads. Whne I first compared the Autolites to the Motorcraft plugs, I thought the same thing.

RE: Dispelling the NGK myth

exact same plug i use in the vette on the 100-200 shot, might be a little cold on the lincoln, they foul out very quick but its the best dam plug