PI head help.
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PI head help.
FORDMUD December 13th 2010, 10:53 pm
Looking for porting tips and pics specific to the PI head. I am a member of the RHP site. I'm planning a good bowl blend and some short turn shaping. Concerns are the odd transition from the bowl to the seat behind the guide on the exhaust. Pics of D0 and D3 don't look like my D2oe's do. I would be stoked with some 340/200 heads that I did in my garage. I'm hoping I can do it without enlarging the ports too much.
FORDMUD- Posts : 290
Join date : 2009-02-09
Location : Meridian MS
Re: PI head help.
schmitty December 14th 2010, 4:39 pm
You can contact Scotty through a PM for his personal take on this. 
schmitty- Posts : 4538
Join date : 2008-12-02
Age : 54
Location : Holdrege, NE
Re: PI head help.
The Mad Porter December 18th 2010, 5:27 pm
The PI exhaust port is a smaller and somewhat better version of the iron cj exhaust port. Its just not as tall at the exit. The short turn height is taller therefore a bit better.
Use a wide 3 angle cutter with a .060" wide 45 degree seat, bowl should be sized at 86 to 87% of the valve diameter, the seat contact mark should be just outboard of center on the valve's 45 degree angle. When you open the bowl you roll the short turn radii right to the 45 degree short turn, roll the bowl up to the 45 degree seat too paying careful attention to the area on the chamber side where the large hollow is. roll a gentle radius from the seat around to the hollow. In the end there will be little if any of the 60 degree angle left above the 45 degree seat. The bowl will or should be assymetrical. wider from short turn to back of bowl vs. side to side.
The PI heads actually have a pretty good exhaust port when shaped properly. The hollow area makes the port noisey but it still makes good power. Flatten the head bolt bulge, raise the roof about .060" and be very careful of the guide area on the intake side of the port. Water is close so dont get aggressive there.
2.25" / 1.76" valves are fine.
S
Use a wide 3 angle cutter with a .060" wide 45 degree seat, bowl should be sized at 86 to 87% of the valve diameter, the seat contact mark should be just outboard of center on the valve's 45 degree angle. When you open the bowl you roll the short turn radii right to the 45 degree short turn, roll the bowl up to the 45 degree seat too paying careful attention to the area on the chamber side where the large hollow is. roll a gentle radius from the seat around to the hollow. In the end there will be little if any of the 60 degree angle left above the 45 degree seat. The bowl will or should be assymetrical. wider from short turn to back of bowl vs. side to side.
The PI heads actually have a pretty good exhaust port when shaped properly. The hollow area makes the port noisey but it still makes good power. Flatten the head bolt bulge, raise the roof about .060" and be very careful of the guide area on the intake side of the port. Water is close so dont get aggressive there.
2.25" / 1.76" valves are fine.
S
The Mad Porter- Posts : 230
Join date : 2009-08-07
Age : 61
Location : Tacoma, Washington -
FORDMUD- Posts : 290
Join date : 2009-02-09
Location : Meridian MS
Re: PI head help.
rmcomprandy December 21st 2010, 11:59 am
As Scotty has eluded to ... leave the back wall pretty much alone and the largest flow increase will be with the shaping of the short turn.
I don't have it in front of me so I don't remember which side however, one side of the short turn should end-up higher than the other side.
I don't have it in front of me so I don't remember which side however, one side of the short turn should end-up higher than the other side.
rmcomprandy- Posts : 6157
Join date : 2008-12-02
Location : Roseville, Michigan -
Re: PI head help.
FORDMUD December 21st 2010, 1:18 pm
If someone has some pics that would be awesome... I'm a visual learner. 
FORDMUD- Posts : 290
Join date : 2009-02-09
Location : Meridian MS
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