21/12/2023
Not many posts this year sorry, been really busy! Here's few photos of a nice 4G63 Mivec head in the shop currently. Usually I have to skew my port programs all over the place to chase core shift in these heads, but this one was exceptional in that regard. 35.00mm intake valve, 1.20mm wide seat, into a 60 then an 85 to blend. 90% of valve size at the bottom of the 60. 1.96 sq/in SCA at the port divider. Next to no top cut is intentional as it screws up my desired back heights for these builds. 30.50mm exhaust valve, 1.50mm wide seat, 9.00mm radius throat cut, starting at 65 degrees off the bottom of the 45 giving a 88% throat to valve relationship for this application. Head marked to the actual bore and chamber programs shuffled to align perfectly then basic hand finish (the owner is an expert hand finisher ;) ) I shrink my port programs just under the seat insert to leave some for hand blending, (this saves cutters too). I use a Rottler P69 5 axis machine for ports and chambers and a Newen BB single point cnc for seats. This head gets Ferrea Comp Plus valves, Kelford Cams, guides and springs. Next step is a light surface mill then on to batching springs etc for assembly. Tomorrow and Saturday is a run of Ford Falcon AU heads, then finally a holiday! Take care, see you on the other side
