38mm exhaust valves

I have a spare 530 head that I want to improve for my turbo car. Bigger valves is some thing I want to do but I don't know what to look for or where. What have you guys done.

That's exactly what I did on my head. At the time, you could get them from Knox, but he's pretty much out of business now. There should be enough material in the stock valve seats to make room.

Going 2mm on the exhaust is asking a lot from the stock seat. It places the head of the valve right near the edge, and you can't run a 30? cut at the top. Also, unless you're also boring/grinding out the seat inner diameter, you are just adding a heavier valve.
I would recommend 1mm larger with bored out seats, or 2+ if you replace the seats.
As far as valves: You can either order custom from SI/Manley, or if your machinist is halfway decent, they can make VW-aircooled valves work. I would recommend CB Performance single groove valves and keepers. You may have to shorten the tip of the valve or move the groove down depending on how you machine the seats. If that's not done correctly, you won't be able to shim the valve clearance properly due to the limited shim sizes.
Valve stem protrusion should be 1.700in from the seat base to the tip of the valve stem.

Depending on your timeline RSI should be coming out with a correctly fitting valve from Ferrea before long. Pat's been working with that but is out on med leave, though hopefullyl he should be back to this project and a few others in the next couple of months.

Otherwise yes, the VW valve thing can be made to work but it's a pain in the but to do, even for a skilled machine shop.

Kl racing 38mm ss valves are 35$ can each I sent them a email for a shipping quote.
I dont want the get new valve seats but if the price is right I guess I will go that way.

brod said:

Kl racing 38mm ss valves are 35$ can each I sent them a email for a shipping quote.
I dont want the get new valve seats but if the price is right I guess I will go that way.

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Those are some expensive valves. Call up SI Valves and have them make some VW valves 0.100 shorter. Or send them a valve and say copy this and make it a larger diameter.
Valves from SI are around $15 each.

If RSI gets some farrea valves, that would be sweet! They make some nice stuff. We talking undercut stems as well?

Pretty sure they will be undercut, don't have details just yet.

Honestly, I'm beyond pissed with the SI's I had in mine. 30k on them, the contact surfaces are toast, keeper grooves are junk, and they didn't fit. That's 3 strikes for a cheap valve, so yeah, I'll ante up for something of a better quality if it means not having to do it a 3rd time.

As for the OP, 38 is a stretch on the stock seats and doesn't leave much room for heat dissipation into the head...

I've had good success with KG Trimnimg in Sweden. Their English is fine and they have parts in stock and shipping has always been fast. I've also done 38 mm a few times and have had no issues with the seats. I've just prepped a 530 for my 242 turbo swap, so can't comment on how it will all work in a turbo head. Fredrik at KG was unconcerned.

the stock 3 groove design with a non clamping lock are not good for a performance app. with the lock not clamping the valve the grooves are going to get beat up no matter the quality of the valve.

the old VW trick of filing the keeper so they can clamp or getting some keepers made that clamp the valve is the only way to ensure no groove failures if sticking with the 3 groove design.

gary yours are the only ones i know of that have had a contact surface problem of the 100's i sold. maybe yours were a bad batch, maybe the seat material used isn't a good match, maybe your egt's were thru the roof, hard to tell.
even if you had inconel valves , the seats would not make it past 30-40k without needing replacing. i've worked on a couple heads that had contact surface issues with valves from other manufactures than SI , one was due to tune, the other because of a valve seat material being too hard (not matched to the material of the valve).

i recommended EGT sensors on any high output setup and if you can tune with a 5 gas analyzer

i designed and worked out a direct fit single groove setup years ago but never did it because 90% of the community would never pay for a complete high end valve train package. i decide not to have my money tied up on the shelf , so i never put them into production

speed cost , how fast do you want to go ?

Agreed on grinding down the keepers. The gap between them is key.

Eh, I dunno Lawrence, you and I have discussed this, I've got 2 other known problem motors and think another one has just come to light as well, with similar issues. the stock head with 25k on this motor and I haven't had to touch the valves in terms of clearances, so I don't think heat is the issue. 2 of the other motors I know the background on are stock motors as well, one of them driven like a grandma, probably never seen 5k, so definitely not a heat issue. That's kinda beside the point though...

I bought a set of 37.5mm valves and matching uprated guides ( better heat dissapation??) from Fidel back in 2007ish when at Carlisle. Fitted them to a 531, had the machine shop bore the center of the seat out ( Fidel said to go with 85% of the valve head for the bore) after pressing in the new guides, then I transitioned the runners slightly to ensure there was no step. Has a brand new IPD turbo cam, new shims, etc... but life got in the way back in 2008 so I'm thinking of dusting it off and finally installing it this summer.

I don't see the valves for sale on Triangles/Knox ?? for B230s, hmmmm... but anyway, there appeared to be lots of meat for the 37.5mm stainless valves and it required only minimal boring and porting to fit.

I'll let you know if it blows up this summer.....

91 coupe 3.31 LSD, M90, IPD suspension stuff.

brod said:

I have a spare 530 head that I want to improve for my turbo car. Bigger valves is some thing I want to do but I don't know what to look for or where. What have you guys done.

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