Hard chromed Stainless valves in iron guides

Relevant specs listed here question is further down

Motor specs:

400 flywheel hp at 10psi

4.0 OHV - cast iron heads with iron guides and hardened valve seats.

500/500 lift cam so Im running double the stock spring pressure (comp 988s springs)/stock valve lift was 270/300 ( the heads have been machined to fit the springs at correct installed height)

Question:

Im worried about breaking the 2 piece valves because of the mods, so I want to put one piece stainless instead

Theres a lot of conflicting information on the internet regarding SS valves and iron guides so I bet this is the best place to ask.

Can I run the hard chromed stem SS valves in the heads? I would also polish the valve stem with 500 grit and wd40, then hone the guide with 320 grit flex-a-hone to provide a smoother finish between the two surfaces.

Thanks in advance

-GHJ

Nobody got any experience with this?

I would be talking with engine builders or the valve vendors for experience.

Why do you think a 2-piece valve can't handle double the spring pressure? Do you have experience with this?

Is it possible to machine the heads for different valve guides?

stock style 2 piece valves are likelier to break at the head and drop into the chamber, where one piece is likelier to bend and not break off(thus not completely destroying the engine.)

Have you any experience with putting stainless valves in iron guides or any information on this?

the guides can be machined for bronze K-liner, but sadly no shop is competent enough in Iceland.

I do not have experience with stainless valves and iron guides, and judging by the lack of response, I suspect very few folks here do either. I was just trying to suggest better sources or alternate solutions. Good luck with your project.

First thing I'd suggest, as others have done, is to contact the supplier(s)/manufacturer(s) of the valve you're considering and see what they advise - it may be hard chroming, TiO₂ coating, or some other option, or none at all, depending on the SS alloy used.

It isn't clear if you are referring to sintered CI guides fitted to the head, or the head material being the guide?

If the former, you 'should' be able to press them out and press in bronze type material guides - sintered CI is fine for most applications, but may be a problem here, becuause of possible breakage. I wouldn't use a thin-wall insert, because while it may reduce possible wear, it will further stress the guide and increase the chance (IMO) of failure.

If the latter, you can buy the kits - https://www.cylinderheadsupply.com/stkguinki.html - and guide(s) required - give them a call, and should be perfectly capable of doing it yourself, with some care. I have had heads done, by a GOOD machinist (and that acknowledges some are "less than" good) and been VERY happy with the clearances and service life, but those were OEM valves in lightly modified engines.

Getting all the liners, and the tools, can be rather expensive, so if you do decide to go that route, it may be easier and cheaper to send them to a reputable 'shop in the USoA or Canada?