It's interesting. One year I overheard them (ich) talking about some guy who was irate that they ruined his hemi heads when converting them to dual plug. The one guy said those heads should never be made dual plug, the other said yeah, but that's what he asked for, so that's what he got. I had them figured out then. Total jerks.
I spoke with that customer a few years ago at Carlisle. IIRC, He said the rockers hit the spark plug tubes. Russ told him to dent the tubes for clearance. His answer, "How the he** do I change the spark plugs"? Last I was told, they made a great doorstop.
