What the heck is this on these ford heads?

[travis]

This particular head is a E5AE-CA casting, but I’ve seen this on every ford head I have around here.

Sometimes it’s hard to get perspective from a picture, so my best explanation would be a 45* seat, then a 135* cut below that, followed by another 45-ish cut and then on into the bowls (forming a sideways V between the 45’s). It’s on both the intake and exhaust, but does not go all the way around. It’s on the long turn side of the intake, and the short turn side on the exhaust.

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[PRH]

I don’t “know” the reasoning behind it, but just assumed a “0” deg top angle and a 90deg bottom angle make it so the seats don’t get as wide when they recede.

Probably some anti-reverse flow benefits as well.

[Carnut1]

I have seen that on a bunch of Ford heads and Chevy tbi heads. I thought it was for fuel sharing. That by no means means I am right. I do know when bumping valve sizes that all goes away and power goes up

[Carnut1]

I have seen that on a bunch of Ford heads and Chevy tbi heads. I thought it was for fuel shearing. That by no means means I am right. I do know when bumping valve sizes that all goes away and power goes up

[Ken_Parkman]

Probably the fastest and easiest machining to accommodate machined to cast tolerances (both sides) and make a seat on a production basis.

[mag2555]

Ford does that a lot and you can see it clearly in the chamber on the left of this 2 bbl Cleveland head.

Since Ford does so on both Intakes and Exh seats it ain't for fuel sheering folks so it's for other machining reasons , of what I can't say!

[Carnut1]

Ford does that a lot and you can see it clearly in the chamber on the left of this 2 bbl Cleveland head.

Since Ford does so on both Intakes and Exh seats it ain't for fuel sheering folks so it's for other machining reasons , of what I can't say!

Right, on the exhaust it is to cause turbulence and reduced flow! HA HA