S54 Cylinder Head Valve Train .... Stuff

[JakeM346]

So I've really gone into my engine again.
And since i didn't find this stuff i was looking for in the internet i just researched it myself and this thread will be my small brain brige.

So this ugly thing was my Cylinder head. Obviously someone was doing a lot of longlife intervals.
But in general the Valve train was in a pretty good condition. No real run in marks on the cam nor followers.


However the valves were done as well as the guide.

Now coming to the Interesting Stuff:
Valve Guides: CAD file of those see the CAD file thread. Very odd shape in fact.
The Originals are made from Phosporus Sinter Metal (Version or Iron) with about a 3/100 mm of a interference fit.

The Valves are even more special.

Exhausts. Are Bi Metal Sodium filled. However they end very high which means that the stem material is different from the intake valve stem.
They are most likely made from
(X53CrMnNiN21-9
- X50CrMnNiNb21-9 ) These two only go up to 780/760 degress tho so most likely not suitable for the S54
NCF 3015 (NIREVA 3015)
Nimonic 80A
The Tip of the valves is probably X45CrSi9-3 because it is induction hardened.

For the Intake Valves they are Bi Metal
With the Tip and Shaft most likely X45CrSi9-3
and the lower part most likely X60CrMnMoVNb21-10

How do i know this.
well X45CrSi9-3 and X60CrMnMoVNb21-10
are magnitite so = magnetic
The rest ist austentite so = not magnetic.

Also the Shafts are Chrome plated.

I will adapt this thread as i find time

[JakeM346]

Okay now continuing this journey. The exhaust valve steel I’ve narrowed down to either X53CrMnNiN21-9 or
- X50CrMnNiNb21-9 ). The best tell here is the fact that the valve is chrome plated just until a bit before the valve head. However if polished it’s possible to spot the difference between chrome plated and stainless steel (more yellow/ goldish) which basically guarantees (in combination with the weight) that it’s a CrMN Steel.
However the difference between both doesn’t matter that much as both have a Thermal expansion Coefficient of 11.9 x10^-6/K
the Valve guides are most likely to be GGP70 so basically grey cast iron with higher phosphorus content. That was in fact already pretty special for that time.
GGP70 has an thermal expansion Coefficient of 12.5
also be incredibly careful if ever removing those guides even if they are pulled and the head is heated they gall.
best way is to bore them out to M10—M11 so they lose a lot of there pre tension and then pull them (while heating the head to 100degrees Celsius)

[JakeM346]

Ok soooo i was wrong.
I‘ve now come across some bmw documentation…..and
the intake valve is mono metal but I was right with X45CrSi9 (probably not magnetic in the front due to the hardening or some other armoring)
and the exhaust valves……are indeed super expensive NiCr20TiAl so better known as Nimonic 80A and of course bi metal sodium filled with a tip from X45CrSi9
so don’t buy that supertech crap because those valves are as I know also nimonic but unlike the factory one that cost around 50€ they are more expensive and not sodium filled+they are heavier…..

also the finger followers of the valve train are fine cast 21NiCrMo2
and the camshafts nitrooxidated shell cast GGG-60

so basically this stuff all super expensive to produce and bmw prices are actually cheap compared to aftermarket and normal bmw markup

ah yeah and word of caution after handing my cylinder head away and for new valve guide……
know and check your machine shops
bmw specification for valve guides is 6H7 which means 6,000 - 6,012 mm

what I got from the machine shops was all on the topper end of this spectrum and many were over around 6,020
which for a valve guide is…..unacceptable
honestly if you want it done right better buy the new cylinder head from bmw
….what I gotta do now because the seats won’t have enough material left in them

[JakeM346]

Also quick fyi I‘m about to open a crankcase thread going into ovality of the main and rod bearings as well as materials, tolerances and clearances…
so maybe if interested keep your eyes open

[Gt4]

I have a spare cylinder head for sale if interested

[JakeM346]

I have a spare cylinder head for sale if interested

nice might come back to that but I’m in Germany unfortunately.
how many miles on that head tho?

[Gt4]

nice might come back to that but I’m in Germany unfortunately.
how many miles on that head tho?

Oh forget about it than, shipping price in Canada are absurd...like 2-3x what it cost in USA

[m3_sancho]

Sorry to hijack your thread, but it's head related. If some of the valve springs are weaker than spec, is it ok to shim them to reach spec or is it better to buy a new spring?

[JakeM346]

Sorry to hijack your thread, but it's head related. If some of the valve springs are weaker than spec, is it ok to shim them to reach spec or is it better to buy a new spring?

Nah nah feel free to throw stuff in here. I’m open for discussions, info…..anything

how much shimming are we talking?
what are the measured deviations in spring pressures?

What are you trying to achieve….balancing minute differences for a race build or in your case compensating spring pressures loss.

honestly said tho from my standpoint bmw spring aren’t that expensive so I’d save myself the headache and risk of a fatigue failure of the spring