Question about replacement seat ID profiles

[Datsunworks]

Hi
I'm trying to get a little info about valve seats. I noticed in the SBI catalog that some of the seats are straight wall ID and some are a tapered ID. Anyone have any idea why that would be?

Also since the seat is a press fit wouldn't a lets say a .300 depth be better than .250 depth for heat transfer as well as holding it in?

Thanks
Derek

[BillK]

derek,
I think the tapered seats are just to help match the oem profile. As far as the depth you are probably correct but you have to know if you can cut the head that deep and not get into or close to a water area. That is the reason some seats listed are a lot shallower than others. If you have any questions about a particular application send them an e-mail. Tech@sbintl.com I have been using their valves for close to 30 years and their tech support is one of the reasons along with great products.

[Datsunworks]

Hi Bill

Thanks for the reply. This is for a custom cylinder head I produce and the depth is fine. I really bulked up all that area when I designed the casting. No kill like over kill I always say.

I sell the heads without seats or guides and that is creating some issues so I've decided to start selling them loaded. I don't know a thing about valve seat cutting as far as it relates to power but in the casting world having plenty of machine allowance is a lot better than not enough. My thoughts were whomever was cutting the valve seats would have more to work with if it had a straight wall.

Thanks
Derek

[ProPower engines]

The best thing you can do for a performance head is stop using SBI seats. They are not the best HP seat to use.
I only use Dura-bond 7000 series seats the same as all the major cyl. head manufactures like Dart Brodix RHS EQ etc.
The other budget heads I feel use seats that are too soft for HP and the seats used are more for an OEM only application.

That said there is more options available from Dura-Bond and you can order custom seats if you use lots of a single part number.
They cut better for those that are doing HP builds and they out last the other brands of seats.