Oversize valves in a 12v head

[Drothgeb]

I was checking into going with oversize valves in my new head. But after checking with the valve supplier. Head said that .100" oversized valves will require seats to be installed due to cutting through the hardened area of the existing seat to make the valves fit. I'd rather not install seats in the head. Anyone have input on this?

 

[fairallbilt]

Ive always heard 24v havin trouble but not 12v as much...maybe someone else can help you out more...

 

[97rada]

Watching

 

[murphy41]

Are you just putting exhaust valves in the intakes or going bigger on both?

 

[Drothgeb]

At least exhaust, maybe intakes too. I can get the valves for a good price, and I can cut the seats, but I'd rather not have inserts. So that's the main thing holding me back. The main reason I would do intakes would be for the 45 degree seat angle.

 

[Badbrad3701]

Watching

 

[2Tone12V]

Call Haisley. Don't remember how large the valves were, their biggest I believe. But I'm almost certain seats weren't used . And the valves damn near touched. Sorry I could only give "I think" answers. I've have two of those heads now and never noticed it if they were there.

 

[cumminsman315]

If it comes down to putting seats in I wouldn't be too worried about it, just make sure you use plenty of press on them.

 

[Drothgeb]

From what I could find out, the induction hardening goes about .030" deep. And, I found a Cummins spec that says if the seats are cut more than .010", install seat inserts. So if you go with oversize valves, you should do inserts.

From what I read though... If you cut the seats oversized and use new valves, it will last for a while due to the fresh hardened surface of the valve. But, if you cut the seats, and use valves that have been refaced. It won't last very long due to metal transferance between the two softer surfaces.

 

[seeker1056]

gotta remember that all specs are based on a motor intended to last a half million miles.
race motors are not built for longevity.
my current motor has been runnin intakes in the exhaust side without seats for 3 seasons with little to no discernible issues
will you need to touch up the seats every time you tear down - maybe - but then that's the nature of a performance motor
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