440 motorhome engine

the additional holes around the plugs are to help cool the plug and reduce detonation. I have a 78 mh 440 in my 66 coronet. I have the cast crank, 452 head version. I added a "hemi grind" hyd cam, performer intake and 750 eddy carb, shorty headers. Runs decent for a mild set up. Still need some gears.