With the new TFS 21* heads out, I have seen some mentioning of rolling stock heads being done to decrease the angle for better flow. Obviously the intake manifold would have to be milled to accept a change in angle, and header clearances could be affected some. So for those with experience with this on our cars, what has to be done to make it work, how far can they be rolled, and what kind of gains could be realized with rolling the heads for a lower angle?

PS - The reason I am curious about this, is that if it is possible to roll the heads say 1-2* and gain say another 10 cfm in head efficiency and not have to use custom headers to do so, then rolling a set of the 21* heads 1-2* may make for some nice extra potential in a smaller runner head.

Discuss amongst yourselves.

 

very interested as well.

 

It's not worth the time or money in a street motor to do that cutting and have to correct the intake face and all head bolt holes. The only time to angle mill heads anymore is if you are in a spec racing class and that's what's needed to get your compression up with a flat top piston rule.