MTFCA Forum

Any suggestions on the best choice of spark plugs for the Model B Rajo head. Thread is for 1/2" pipe but I can use 14mm adapters. What would be the best choice of plugs? Running a DU4 magneto, where should the plugs be gapped? Did a search on the topic but didn't find anything definitive. Thanks

.025 gap stated here. I’ve read between .019 -.025. Ive always heard you tighten them up about half from normal ignition source.

Thanks Tim, I remember reading about the reduced gap with the DU4 but couldn't remember what was recommended. Yanked the adapters out of the head and bought 4 Autolite 3095's from O'Rileys in town. We now have 3 auto part stores within sight of each other. Someone needs to investigate that business (and mattress retailers) for money laundering or business fraud. Doesn't make sense to me with so many lease cars on the road and the absence of auto mechanics or mechanics in general taught in school?

Yup, we have 4 big ones within a half mile of each other. This in a town that has lost population for many decades and doesn’t have even 1 decent restaurant. I only trade at the small mom and pop auto stores, but they are all gone now. AND, when was the last time you saw someone wrenching on a car in their driveway?

Just fyi. I've been running Champion X plugs in my B Rajo for 52 years. On the road and on the race track. FU 4 magneto. Always set them at 0.25 and I've been totally satisfied with the performance.

Ed aka #4