Uncharted territory .................. what do we think guys ?The second plug .... short reach plug so the threads / body on the inside [ nearest crown ] are level with the opening where it enters combustion chamber and remove / smooth out the threads on the other side .... or - what ??
You never want the sparkplug threads to protrude beyonde the hole, so if that's only got depth for a short one, then that's the one to use. Cheers,Greg