Replacement exhaust/inlet valve options

[AMBROSIA]

I'm looking for tried and tested options over the stock units for wbx engines.
Application will be AMC heads with stock sized guides and seat heights.
I can't buy into the fantasy realms of titanium, but do need a quality set that are going to stand up to higher revs and spring pressures.
Stainless has been suggested but my machinist has advised against them.
The main concern is of course the two part oem style exhaust valve splitting and dropping.

Thanks for any input

[Piledriver]

Good SS valves from SI, Manley and others have been use on ACVW (and all other types of engines) for ages with great results.
If you buy "good" heads from any good vendor, that's what you will get.

Consider finding another machinist who keeps up with at least late 1970s tech
(around when when they started adding hardened tips on SS valves)

Some cheap valves lack this common feature, or are made from recycled bean cans.
Don't use bargain basement junk, no worries.

Feedback on the recent AMC heads is they have OK valves and seats.
They once were made from peanut butter or such, and the valve and seat would be beaten into each others shape by ~40K miles.

If you MUST use valves with non-hardened tips, they sell lash caps made from much harder steel to take the beating.

The TRW valves are fine in the stock sizes, in any case, just make sure the NEW CrMo keepers/collets are ground so they do NOT touch on both sides when on the valve, if they "float" around freely the grooves get chewed up and the engine ~always gets fatal indigestion when swallowing a valve.

Almost all OEM exhaust valves are two piece.

[AMBROSIA]

I think his issue with stainless is lack of overall hardness.
The stems are not an issue as lash caps will be used.
He fits Manley to his T1 and T4 heads but cannot source in WBX dimensions.
He's at the forefront of UK top end race engines and has been for many years, so it's not a case of ignorance when it comes to his opinions but the bigger issue is he does not get involved in WBX tuning as it's rarely done.

From my experience I've not been impressed with the amc supplied valves having had one with a badly undersized stem, so much so I thought the guide had gone.
The subsequent replacement TRW valves suffered tip pitting after less than 10k requiring lash caps despite running oem style rockers and adjusters.
You're right about the keepers, shocking fit, but as you say after careful grinding fit fine in the grooves.

I know several guys on here have wbx race engines so wondering what they use?

[buildabiggerboxer]

I have flowed AMC heads on my work bus, they have logged 12000 hard miles but I've not done a visual inspection as there's no valve noise, I will check things at the next service however, AMC valves should be fine these days, Jim at TESS must have many hundreds running out there and says they are ok.
I can't know why stainless are frowned on when all performance race motors use them, most use lash caps tho' as I do, other than having them made, you could machine up oversize T4 valves to suit, the problem is the 9mm Wasser exhaust stem, easy if you change the guide, use your original German inlets with lash caps and find or have made some 35.5 8mm stem exhausts.

[Piledriver]

For the oversize valve the t4 ones work IIRC.

I also recall mention of a Mercedes ex valve option, but that was 38mm and sodium cooled.

The trw valves work fine in stock t4 apps but that was with single springs.

The only time I recall ever seeing tip pitting also had adjuster pitting, I suspect it was due to low zddp oil.
(The adjusters>tip is also high load/point contact lubrication)

I want to say 9mm stem 36mm dia TRW replacements for the 2.0 Porsche heads exist, but I always went with 8mm stem and new guides.
One could always use the sodium cooled ones but $$$ and need turned down a touch @36mm.

[buildabiggerboxer]

For the oversize valve the t4 ones work IIRC.

I also recall mention of a Mercedes ex valve option, but that was 38mm and sodium cooled.

The trw valves work fine in stock t4 apps but that was with single springs.

The only time I recall ever seeing tip pitting also had adjuster pitting, I suspect it was due to low zddp oil.
(The adjusters>tip is also high load/point contact lubrication)

I want to say 9mm stem 36mm dia TRW replacements for the 2.0 Porsche heads exist, but I always went with 8mm stem and new guides.
One could always use the sodium cooled ones but $$$ and need turned down a touch @36mm.

All valid points, tho often hammered stem ends/adjusters go with weak hydros being the culprit, same as pitted lifter problems in a solid lifter motor, folk jump straight down the makers throat without thinking, blame any one but themselves, when it's usually down to too wide a valve gap allowing the lobe to crash the lifter beyond the opening ramp, same with a collapsed hydro lifter, allows bashing the adjuster into the valve tip too hard.
If ever a race motor was built for solid lifters and zero gap valve lash, it is the Wasser, mine are no noisier than a hydro motor even when hot, so we'll controlled is the coolant expansion factor
Suited to chromo push rods, that and noise damping by the coolant jackets, I lost 3db on our race noise checks just going over to the Wasser, it used the same silencer from my previous air cooled motor, don't sound like much, but 3 db is a considerable reduction.

[AMBROSIA]

Quick update:

The TRW valves I though I used previously where actually made by Gieffe.
So, after much searching and weighing up what's been said on here i'm going to source some TRW for this build.
KS is Germany stock them but i'll be looking for a UK based supplier first.
Jim has kindly offered to check his suppliers to see what's available, the nice chap he is.