The V8 Owners Forum -

Just start to replace my RV8 head gasket, and take valves off.
All new 10 000km drived new exchaust valve seats are pitted.
They are yellow colored like copper (I think they are Beryllium Copper Valve Seats?)
I have got Stainless steel valves also..

Found this on web:

I talked to DelWest about these seats for use in a high exhaust temp industrial application, and they said "No" on using these seats with a stainless valve. They said it wasn't the material of the valve but the WEIGHT of the valve. The heavy weight of a stainless valve would hammer the seats in. The softer material of the copper-based seat needs the light weight of a titanium valve to help it keep its shape.

Is this true?

I understand Eales etc are using those "copper" seats also?

Timo, you should contact directly REC as they produce UBV for Eales, etc...

kokkolanpoika wrote:Just start to replace my RV8 head gasket, and take valves off.
All new 10 000km drived new exchaust valve seats are pitted.
They are yellow colored like copper (I think they are Beryllium Copper Valve Seats?)
I have got Stainless steel valves also..

Found this on web:

I talked to DelWest about these seats for use in a high exhaust temp industrial application, and they said "No" on using these seats with a stainless valve. They said it wasn't the material of the valve but the WEIGHT of the valve. The heavy weight of a stainless valve would hammer the seats in. The softer material of the copper-based seat needs the light weight of a titanium valve to help it keep its shape.

Is this true?

I understand Eales etc are using those "copper" seats also?

I think the weight of the valve would play less of a part than the strength of the valve spring.

Are the seats worn, just pitted, not sealing, anything else ?

What camshaft/valvetrain do you have ? And are valve clearances or lifter pre-load within spec ? And are the valve springs adequate to cope with the camshaft and rpm you are using ?

If tolerances were within spec when you built it, are they now out of spec ? ie have the valves or seats receded into the head tightening up tolerances ?

I think I seen you registered over on Pistonheads Engine section. This would be a query for Dave Baker/Pumaracing if he can be drawn to it. Although I'm almost sure not that long ago there was a very similar question asked, and the problem was poor valve control.
Might actually have been Neal on this forum with his twin turbo engine ?

Hi thanks for info.

I have got Mechanical M238 camshaft, Harland sharp roller rockers, Valve clearances is 0.5-0.55mm. Realsteel single valve spring.
I found last summer that my valve springs are wrong adjusted/shimmed. They are slighlty loose, inlet adjustment is worse than exchaust, but inlet valve seat is like new. So i think they might be slightly bounched (Inlet at least) when revving 6000rpm. Found this bounche proplem when i install my ITB´s, air cleaner look like explosion, with plenum i can´t hear/notice valve bounching..

I just bought set of crane douple valve spring, and my machine shop made yesterday suitable spring "hole" for those.

Exchaust seat "gasket" surface is only pitted, not hole seat and not valve, valve is like new. I didin´t notice any sign that they aren´t leak???
And machine shop also say that seat "gasket" surface might be slightly widen, couple of tenth of millimeters..?
But i lapped those seats before i install those heads about 3-4year ago..
I don´t have to made any adjustment with clearances. (chek every year) So i think they are quite in specks, but only pitted?

My machine shop say now that lapping valves is "forbidden"/unnecessary when they are made in MIRA.

I can't see how the weight of the valve can cause it to hammer the valve seat as long as the spring is suitably strong. The rate at which the valve closes and the speed that it hits the seat is controlled by the closing rate of the cam's profile. The only time that the valve springs pressure is exerted on the seat is once the cam follower has left the closing ramp of the cam and it on the base circle, the spring pressure should not be massively high at this point.

In my humble I would have thought that its the cam's profile on the closing side that is the area of concern here, of course if the clearance of the followers was not set right then that could also be the cause of the problem, to much clearance will cause will mean that the follower does not follow the closing ramp properly the valve will then hit the seat too hard, too little clearance will cause the valve to overheat and burn.

AJMHO

There is little or no benefit from a narrow exhaust valve seat. There are huge benefits from a wide seat. ie reliability.

The cam profile should control closing, as long as there is enough spring pressure to maintain follower etc contact with the camshaft.

If the Pistonheads search engine wasnt so poop, there are some good threads there

Hi
Be Cu seats are intended for titanium valves with a diamond powder in berrilium surface coating, the combination is intended to work to avoid gaulling of the seats by the titanium valves, the titanium of the valve would tend to pluck metal off the surface of a steel seat. Even so the combilnation, with the much lighter titanium valves (and reletivly lighter springs) they are only going to last race engine distances, 10,000 km is not racing distaces. These seats are not intended for use with stainless steel because they (as you have forund out) have the same gauling effect that they avoid with titanium.
A Nascar team will typically change a set of seats every 2 or 3 races even when used with the right valves because the spring pressures these engines use will have deformed the inserts considerably, the valves will be changed at the same time. I have a set of valves from a national cup (flat tappet cam engine) at home that are 5 races old, you would not credit how the seat area of the valve has deformed.
Best regards
Mike
With high

Machined exchaust seat.. My local race engine builder say´s that they are not Be-Cu seats, it is very rare in Finland. And my machine shop don´t use mask or glove´s.
My local race engine builder think that they are some copper/alloy seat´s?



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Valve seat OD look very large compared to seats used on my TVR Tuscan Challenge heads :

My valves are 43/38mm.. I think you is 43/37mm max?

kokkolanpoika wrote:My valves are 43/38mm.. I think you is 43/37mm max?

yes.

specs of my heads here : http://www.v8forum.co.uk/forum/viewtopi ... ght=tuscan

Spoke to my local race engine builder/friend ( http://www.proengines.fi ), we measure my old real steel (same as V8 tuner, RPI, etc) DW040 single valve spring´s 1 coill less than STD spring.
Measured 39mm installation height 32Kg and 13mm valve lift (26mm) they only give approx 72Kg pressure. + they look like banana.
So totally Fu... crap.. drived max 10 000km..

STD rover valve spring will give 10kg more pressure with 11mm valve lift (Des Hammill book).

Also measured Crane cams douple spring, 39mm installation height 43Kg and 13mm valve lift 106Kg, so they are ok
Also we found that my valve keepers (locks) are too tight for my valves (3 groove locks) they bite like sharp with valve stem, and they are designed to "loose" fit that valve can spin "freely" and then it can clean valve seat/valve "gasket" surface.
I always think that those locks have to be tight fit, but not for 3 groove locks, i understand that STD rover style locks have to be tight fit?

Any opinion?

Single groove valves tend to he held tight by the collets/clocks.

Triple groove tend to allow the valve to rotate. Not sure if there sre some that hold it tight or not, or if it would be a concern.

As long as the collets are secure in the retainer, that's the most important thing

Well i grind my locks when i made my engine, because i dont know that they should be non tight fit. I read somwhere that minium clearance is 0.5mm between locks.. And book didin´t tell what type locks they are, so i understand that all type..
I have to buy new set of lock´s and hope that they spin freely..?

ISTR 'common' Ford Cosworth collets & keepers are suitable for the REC triple groove valves plus double valve springs.