stainless steel valves

[radish]

Hi all

I'm building a 1903cc for my bus and heads are off to be machined next week. The are stock heads and just wondered if i should take the opportunity to upgrade to SS valves? It won't be a racy motor so is it worth it?

Cheers Darius

[Ol'fogasaurus]

Hi all

I'm building a 1903cc for my bus and heads are off to be machined next week. The are stock heads and just wondered if i should take the opportunity to upgrade to SS valves? It won't be a racy motor so is it worth it?

Cheers Darius

Darius, I am not what you would call an engine builder but I have done a few builds in my time. This is an opinion only: if you go to the trouble of changing over to SS valves (mainly because of the new fuels) then I would also update to hard seats... for the same reason. I did update one V8 engine this way and it worked great and my machinist also thought it was a good idea. As long as you can get the right sized of valves and seats I don't think, for an everyday engine, that you should have a big problem with the update. Again, my opinion.

[radish]

Thanks Lee, I'll check what the cost are.

[Bruce2]

There's no need to upgrade any valve seat in any VW head. They are already compatible with SS valves.

[Ol'fogasaurus]

There's no need to upgrade any valve seat in any VW head. They are already compatible with SS valves.

Bruce, its not the harder SS valves that is the problem it is the seats themselves not being made for todays mix. Where I ride we have been able to get non-ethanol fuel but not every one can and it can be a problem. Engines that were built before the change over to ethanol fuels need to be updated to compatible valves and seats due to the different heat ranges (https://www.consumerreports.org/cro/new ... /index.htm).

Some carburetors' don't like ethanol either as it destroys them quite quickly (I have one myself on my Style string trimmer where the carburetor is useless as I let ethanol fuel sit in it for a couple of days. The additives don't work for doodlie-squat either as the fuel did have the proper proportion of the additive to the ethanol fuel I was stuck with to use).

[Bruce2]

SS valves are not hardened.
There is no problem with the valve seats when using any fuel. Leaded, unleaded, E10, straight gas.... it's all good.
Your warning sounds just like what everyone was crying about in the early 90s when leaded gas was being phased out. Perceived problems never happened and many of us went hundreds of thousands of miles without valve issues on unleaded gas.
To the OP, just use quality stock valves. SS doesn't provide any advantages.

[Ol'fogasaurus]

Bruce, just when was the last ACVW brought into the US.

Remember, I come from the street rodding days and we had to update the engines as they just didn't last long.

[Bruce2]

Bruce, just when was the last ACVW brought into the US

Your link above says possible problems with cars from model years 2001-2009. What's that got to do with our 1970s technology engines?

The engine in my Beetle has non-SS valves against stock valve seats. It's at 103k miles now and has only had unleaded ethanol blended gas. How much longer do I have to keep driving it before there is going to be trouble with the seats or valves?

[Ol'fogasaurus]

Bruce, not a place to argue this out and this is my last input on this.

If he wants to use the stock valves and seats they will work fine but usually not for as long. If he wants to go with SS valves then finish off the job correctly and install the hard seats.

Yes, the URL only covered back to 2001 but the same problem did not start with those year engines it also affected the older engines as they were built similar. Age wise w/cars I go back into the late 50's and ran into the problem when the ethanol bit got started.

It has been said that we don't need the ethanol now days as the engines are some much more efficient now days; it is for the corn farmer's congressmen that it is being kept alive.

[Marc]

The root of the problem when running "no-lead" fuels is that when valve faces and seats of similar metallurgy come into contact, molecules are ripped apart, leaving pits in the surface which can then lead to "wire-draw" failure. Tetraethyl lead was a relatively cheap way of raising octane that provided the bonus of providing lubricity between the contact surface. Long story short, the more dissimilar the metallurgy of the valve face & seat, the less of a problem. Stainless valves against stock seats provide enough dissimilarity; so-called "hardened" seats aren't needed. The other benefit offered by leaded fuel was high-temp lubricity between valvestems and valve guides; the pressed-in bronze guides in an ACVW head ameliorate this issue, and the chrome-stems adopted c1967 nearly eliminate it. Stainless-steel valves really offer no advantage over stockers other than availability in larger sizes; they're arguably less likely to catastrophically break because they're softer, but that also makes them more prone to burning. Don't sweat the seat metallurgy - if you freshen the valve job on schedule, things will be fine.

[66brm]

Stainless valves will typically flow a bit better in the same head due to the design of the radius on the back of the valve. This is comparing the same size valves, back cutting the valve (port side of the seat) with just a single angle will improve flow also

[Bruce2]

If he wants to use the stock valves and seats they will work fine but usually not for as long.

Now you're saying stock valves on stock seats are incompatible????

If he wants to go with SS valves then finish off the job correctly and install the hard seats.

If he goes to an auto machine shop and asks for hardened seats so he can use SS valves, I guarantee they will do one of two things. Either they will talk him out of it because it's not necessary, or they'll take his money and do nothing to the seats but tell him they put them in.
Hot rodders have been proving for over 40 years that stock VW seats are very reliable when used with SS valves.
Maybe you're thinking about the problems when you try to use titanium valves on stock seats? That is a known no-no.

I go back into the late 50's and ran into the problem when the ethanol bit got started.

Mandatory blending of ethanol didn't start until only a few years ago. Not in the 50s.

.... we don't need the ethanol now days ........ it is for the corn farmer's congressmen that it is being kept alive.

I agree with you there.

[raygreenwood]

Stainless valves are not just an generic item...like all stainless valves are good because they are stainless. The same goes for saying that stainless valves flow better because they have a better radius.

That all depends on whose valve and how they machine them. Every manufacturer of them is different.

Stainless valve have advantages of less risk of corrosion from water and really poor fuel and sitting still for long periods....but outside of that there is no benefit unless the particular valve has been designed and machined different...and in that case its not the material...its the design.

Also its been my experience..albeit a decade ago or so....that stainless valves like most stainless material...and again depending on alloy...are a bit stretchier under high temps. A lot of the stainless valves appear to be one piece instead of two or three.

Also I personally do not like using ANY valve that does not have hardened tips.

The original VW valve seats....never had any issues with unleaded fuel .They were high in nickel content. The vast majority of cylinder heads that had issues with no-lead fuel were cast iron detroit products that had NO valve seats. They were running on machined cast iron surfaces and without the lubricity of lead, steel valves had a tendency to weld microscopic amounts of the cats iron onto the edge of the valve and rip it away causing valve seat erosion.

Through the 80's the machine shop solution for engines that had this problem was to install machined and pressed in seats....like aluminum head water cooled engines and VW's always had....or stainless valves.

Ray

[Ol'fogasaurus]

I said I wouldn't post on this again but &%$&&%^% Bruce, learn how to read. I didn't say I had ethanol problems in the 50's even though it was being use as racing fuel but as the problem with ethanol in gas came up the different fixes for the valve and seat problems also came up. When I was building a couple of engines in the 90s this was the solution advised. Since then things have changed a lot. I will stand corrected on the need for hard seats; it was the fix then and I have heard it is still being used; right or wrong. I have also bought cars with the valve seats hammered out of the head or the block (Flathead Fords for example) and jamming the valves open.

Some things I looked up to check myself out (something I usually do it if I am challenged)

http://www.enginebuildermag.com/2007/12 ... lications/

http://www.hotrodders.com/forum/questio ... -5064.html

A warning on hard seats on newer thin wall heads.

http://www.enginebuildermag.com/2011/08 ... selection/

Interesting.

http://flotite.com/pdf/resources/seat-s ... -guide.pdf

Very interesting

[radish]

Thanks for your input guys. ihave spoken to the guy who is working on my heads and he has advised for my planned use i'll be fine with stock.