Brad Bez: Feb 2018

The claim over the years that R2 heads are the same as Truck heads is not true. All R series engines used J series 3/8" reach spark plugs. The truck heads, and all others used H series plugs, 1/2" reach. If you screw in a J plug into a truck head several threads will show, and possibly build up carbon, and pre-ignite.


ref . .