"radiased" Merc Heads ??!!

[MrCougar]

Hi, I own a 2.5 Merc. Carb engine,200 H.P.,1993., and Looking at BY-U-BOYZ.COM web (Proyect side), I found that T-Rex, RADIASED the Combustion Chamber of the Merc Heads.
What´s the mean of that Mod????; Radiased the Chambers will improve the Combustion?????.
How many "DEGREES", Do I need to make in the Milling Machine to achieve that correct Mod?????.

Regards, Mr.Cougar

[check88]

mr cougar,the heads on the byuboyz site are the old 2 piece hemi style heads.when you shave these heads down you end up with a very sharp ridge where the chamber meets the squish band.the reason to radius this off is to prevent hot spots in the combustion chamber.i just use sandpaper on mine to knock it down enough,then i polish the chambers.i believe you have the newer style one piece heads,if you are going to have them shaved down your machinist should radius the edges for you.just take enough off to eliminate the knife sharp edge.