Two Piece Valves

R

Ross6860

Senior Member
If you have a choice, don't run two-piece valves.

Here's a nice photo of what happens when the head separates from the stem.

We found coolant pouring out of the turbocharger inlet when we arrived. We knew it wasn't going to be a good day.

The yellow thing is the engine (1260 hp @ 1400 rpm), gray is BOP gas compressor.
 

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I have seen similar damage from forged, one piece valves. I would not hesitate to use 2 piece valves. An investigation into the cause of that failure will need to be conducted.
 
In a Flathead, separation of the valve head & stem isn't as likely to cause the damage shown here -in an O.H.V. engine. I had one do that and the head rattled around in its hole for a bit and beat the seat to death but it never migrated into the cylinder. Maybe I was lucky but I DID continue to drive it for maybe 50 miles after it started to miss. Strangely, there was very little noise.
 
Ronnie said:
There are thousands of 2 piece valves out there you will be fine.

R
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I guess my point is if you are spending money for new valves. I would not buy two-piece valves. Just my opinion.

JWL said:
I have seen similar damage from forged, one piece valves. I would not hesitate to use 2 piece valves. An investigation into the cause of that failure will need to be conducted.
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Failure at the "weld". Believe me, this is not the first, just the only one I had photos of. If it survives the warranty period, oh well, sorry for your luck.

Caterpillar is very close-to-the-vest about their factory problems. I guess if I sold a jillion parts, and had a 1% or 2% failure rate I wouldn't advertise it either.

They re-designed both the material and the manufacturing process for new exhaust valves. I had a factory tech I have a good relationship with tell me "off the record" not to order or install any heads or valves carrying certain part numbers. We pulled our cylinder head inventory and R&R'd any suspect valves. So far, no issues with the new parts.

That failure took out a power pack (head, piston, rod, and cylinder assembly), a turbocharger, 200 gallons of coolant and about 120 gallons of oil. No, it wasn't cheap, plus our down-time.

My other baby, a 351C, is noted for this failure. I don't think anyone would rebuild that engine with two-piece valves (nor would most builders recommend it).
 
Do you think that you are going to have the option of two piece valves or not for a flathead??No one disbelives the failures that have occured as stated,but in a flathead !!!

R
 
Charles Thompson (the T in TRW) developed the process back in 1904 or there abouts. Manufacturers have been doing it ever since. I work on Lycoming engines that require sodium filled valves on the exhausts and there is only one way to get the sodium in there. Henry Ford picked up on the steel stems with stainless heads way back in the early V8 days and probably well before when Ford was making Liberty Engines.
 
Ronnie said:
Do you think that you are going to have the option of two piece valves or not for a flathead??No one disbelives the failures that have occured as stated,but in a flathead !!!

R
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I know some folks are using SBC valves, so yes, they are available as one-piece valves.

I haven't done enough research yet to see what is commonly available, but I'm relatively sure someone would make them. I could be wrong. It would not be the first time.


rotorwrench said:
Charles Thompson (the T in TRW) developed the process back in 1904 or there abouts. Manufacturers have been doing it ever since. I work on Lycoming engines that require sodium filled valves on the exhausts and there is only one way to get the sodium in there. Henry Ford picked up on the steel stems with stainless heads way back in the early V8 days and probably well before when Ford was making Liberty Engines.
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Quite a few engines use sodium-filled valves, and yes it has been done for ages.

Again, I just stated my opinion. If there's an option, I don't like two-piece valves.

In general, I also prefer forged parts over cast, and parts machined from steel over MIM, and rolled threads over cut threads, when there are options.

None of this may be "necessary" in a low BMEP engine like a flathead, but I don't like doing things twice.

There are always exceptions. Ford, notably, made very high quality castings and there is usually no reason to upgrade to a forged crank, or third member, in a Ford street car. Other marques are another story.
 
rotorwrench said:
Charles Thompson (the T in TRW) developed the process back in 1904 or there abouts. Manufacturers have been doing it ever since. I work on Lycoming engines that require sodium filled valves on the exhausts and there is only one way to get the sodium in there. Henry Ford picked up on the steel stems with stainless heads way back in the early V8 days and probably well before when Ford was making Liberty Engines.
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Interesting. In school at Univ. of Illinois (which is supported generously by Caterpillar) we did friction welding of valve stems in the lab. It was supposedly developed in the '60's for Caterpillar. Does the process you are attributing to TRW use friction welding?
 
The original process from 1904 was electrical resistance welding. Originall it was steel to steel in order to better utilize the raw materials. The heads could be cut from larger stock and the stems from smaller so it didn't take all the whittling to make the large stock small. Thompson products (much later TRW) pioneered welding stainless or high nickel steels to carbon steels. Ford likely consulted Thompson when the welded the water jacked plates on the V8 60 engines but by then it may have been a little more common to weld the dissimilar metals.

Friction welding is a lot newer process but has become a lot more common now days.
 
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