visual diff pi vs npi

[infamous209]

lookin at a pair of used pi heads but im wondering how to tell the difference between the two

 

[JDwhite98gt]

It should have a "PI" stamped on the head somewhere. If you look you'll find it, there isnt a lot of writing on them.

 

[Lee12609]

besides the intake ports are extremely different.

non PI on the left, notice its almost perfectly round.
PI head on the right, its a D shaped port.

http://www.f150online.com/galleries/images/634-794-6999.jpg

 

[US Soldier(stang 98)]

most but not all non pi heads are a 11 bolt valve cover and pi heads will 13 bolt holes for a valve cover.

 

[DropTopPony]

Like Lee was saying, the ports on the NPI are tear drop shaped and the PI are squared up more.

 

[infamous209]

awesome thanks for the help

 

[duff daddy]

most but not all non pi heads are a 11 bolt valve cover and pi heads will 13 bolt holes for a valve cover.

Not true, the windsor/romeo head determines the difference.


ALso the combustion chamber is different.
NPI

PI

See the difference

 

[infamous209]

ya pi valves are closer and the npi have that wall in the dome

 

[duff daddy]

ya pi valves are closer and the npi have that wall in the dome

the bottom pic are my heads and I do have over sized valves so that is kinda of misleading i guess.

 

[infamous209]

thats a trick question lol

 

[Lee12609]

the PI has 2mm larger exhaust valves aswell....

 

[infamous209]

well i think with all that help i can go pi head shopping in confidence. Thanks guys