59cc Heads?
01-18-2013, 05:36 PM
#22
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150 your nuts!!!!!!! The most I would go is 130. And a 130 cut is not a true 130. Remember angle and surface of the cutting is not making full contact with the piston face only a smal part of it is. So .130 is only the travel of the deepest part of the cut. Then tapers off. So you really don't lose much. Everyone that flycuts does it for peace of mind. I say check how close it is and if its less then 65 cut it even if its only a hair.
01-18-2013, 05:57 PM
#23
150 your nuts!!!!!!! The most I would go is 130. And a 130 cut is not a true 130. Remember angle and surface of the cutting is not making full contact with the piston face only a smal part of it is. So .130 is only the travel of the deepest part of the cut. Then tapers off. So you really don't lose much. Everyone that flycuts does it for peace of mind. I say check how close it is and if its less then 65 cut it even if its only a hair.
01-18-2013, 09:17 PM
#24
I stand by the idea that different casting makes the comparison invalid though. So you had the same valve angle and a larger valve but was the valveseat at the same depth? Did it take the same depth of milling to hit the chamber volume?
Are the chambers machined? If they are then it is that much more milling that had to be done to get them down to 59cc and that much less PTV you would have because of such.
Guessing you think they are PRC stage 2.5 as those are popular????? in which case they also have slightly larger valves too further limiting PTV
Guessing you think they are PRC stage 2.5 as those are popular????? in which case they also have slightly larger valves too further limiting PTV
01-21-2013, 10:42 AM
#28
True, but flycutting adds the area only right at the valves, not across the entire surface area of the piston. Therefore more cam can be had with flycutting rather then a thicker gasket and more PTV clearance at the same time. Cutting reliefs is a better way to go.
Last edited by R6cowboy; 01-21-2013 at 10:54 AM.
01-21-2013, 12:05 PM
#31
, that's exactly what I mean. Seems there are a lot of people that don't know anything about flycutting, haven't even heard of it before or don't know it can be done safely to their engine. And because they don't know anything about it or haven't been educated about it at all, cutting notches in their pistons sounds a little scary to them. Also flycutting pistons in the garage seems to be a task a lot of people who have never done it before aren't very confident doing themselves. 
