I will have to check as i cant remember. I BELIEVE i am using the standard heat range plug for a 1975 new yorker with 440 as thats what the engine came out of originally.
That's an RJ14YC, ....or NGK's equivalent, waay too hot for hotrodding. 440 I put together over 25yrs ago running 10:1 with the smaller 280°/.474" Purple Shaft, 1.875" headers & 3" exhaust, cold iron intake 750VS Holley,..... happy @34° total........and that's with a MP electronic dizzy,...notorious for a fast curve....
