D5 head-Hardened Valve Seats

Does the D5 head have hardened valve seats? I believe the head I have is from a '77 250.

Thanks

Dave

I don't think the hardened exhaust seats came until D8. I'm not positive though. D5 means the head was made in 1975.

HELLO 72MAV...

ALL CALIF. CAR HAD HARDENED SEATS IN 1974 (D4) AND THE OTHER 49 STATES WERE IN 1975 (D5). YOU SHOULD HAVE THE HARDENED SEATS.

LIVE IN GRACE

LEROY POLL

The seats in your head are "induction hardened". FoMoCo had a process to flame harden the seat area so they would last longer with unleaded gas in '74 and '75 for sure. I'm still trying to figure out what they did with D3 ('73) heads. The C9 and D0 heads are neither "replaceable" nor "induction hardened" for the 49 state engines. California is a wonderment all its own.

I don't believe there is a '76 (D6) head. D7 ('77) and newer heads had hardened replaceable seats.

Any machine shop that does heads can easily cut the heads and insert hardened replaceable seats.

Probably more than you wanted to know

Good Luck

Dennis -

FWIW - I used a D3 head on my 65 rebuild. According to my machine shop, the head did not have hardened seats. I can confirm this since I saw the head prior to the seat installation, and specifically asked the question since I'd never seen a "hardened" seat vs. and "unhardened" one.

Not sure it that translates into fact for all D3 heads, but that is the case with mine.