Twisted Steel Performance
Anything worth doing is worth overdoing.
I have found some differences between a head used on the P400 verses a standard 6.x head...
I'm still finding other things that make this a "different" head.
The casting # are the same but so far that is all, but I haven't cut one up YET, that is coming soon, I'm just too busy with hay cutting right this time, when I'm caught up I will cut it like I did last time and see what changes were made with the castings...
I found the valves are not the same, they are a little larger in the stem base and the height in the seat contact area is also bigger.
I have a new set of 6.5 heads here that I plan to check & record the valve install height " spring height" and also more important the valve depth from the head surface. This is where the major difference could cause piston contact if not checked.
Notice the P valve on the left has what looks like a back cut.. it isn't a straight back cut it's a radius cut, looks to me like someone figured this would help introduce some swirl into the cly. Also notice the larger taller seat area on the left P valve.
Again... P valve left ... stock valve on the right...
I'll have better pics & measurements this week.
Only trouble I see is if at some time in the future valves were needed they would more than likely need to be custom cut due to the lack of ability to purchase them, but custom valve work isn't out of the question at all...
I'm still finding other things that make this a "different" head.
The casting # are the same but so far that is all, but I haven't cut one up YET, that is coming soon, I'm just too busy with hay cutting right this time, when I'm caught up I will cut it like I did last time and see what changes were made with the castings...
I found the valves are not the same, they are a little larger in the stem base and the height in the seat contact area is also bigger.
I have a new set of 6.5 heads here that I plan to check & record the valve install height " spring height" and also more important the valve depth from the head surface. This is where the major difference could cause piston contact if not checked.
Notice the P valve on the left has what looks like a back cut.. it isn't a straight back cut it's a radius cut, looks to me like someone figured this would help introduce some swirl into the cly. Also notice the larger taller seat area on the left P valve.
Again... P valve left ... stock valve on the right...
I'll have better pics & measurements this week.
Only trouble I see is if at some time in the future valves were needed they would more than likely need to be custom cut due to the lack of ability to purchase them, but custom valve work isn't out of the question at all...