spark plug reach

[GOSFAST]

Using a new set of the Offy heads here for a measurement, the spark plug threads measure exactly .540" deep. As seen in the photos below. The .750" long plug and a .125" spacer sets the plugs at the preferred height!

Sometimes it's not as easy to get the correct plugs to work no matter what the mfr recommends! Don't forget you need the correct lengths AND the correct heat range! Offy's have always been a problem with plug lengths, this is why we made the custom spacers I mentioned above!

Thanks, Gary in N.Y.

P.S. If you use the .540" measured thread length and use a .060" gasket the plugs would have to measure some .600" long? Much easier in my opinion to use shims. I recommended to Vince and Tay out at Offy to make the new heads for the more popular .750" reach plugs, this was a couple years ago already!