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New Valve, what's up with the face width variation?

Hi,

Have seven new exhaust TRW 3051 valves. Six are 3051 HC code and one is 3051 GC code, same part, different plant? The GC code has a valve face width that varies, so the face is from 0.119in(3.03mm) at its widest to .008in (2.02mm) at it's narrowest. What's up with that? The other six valves from the same supplier are well controlled, before I noticed this I had used one of the well manufactured valves for lapping two seats so far and am not sure whether to use the one I lapped with in the working car or just install the one with the varying face width values. If I use the lapped valve in the car then I'd have this varying width one to continue lapping the remaining 4 seats. I noticed this when bluing the valves and seats.

Phil


Old 07-31-2020, 06:32 AM
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I have heard that sometimes TRW valves are bent. Chris Flavell had mentioned this was something.to look out for.
Old 07-31-2020, 08:39 AM
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Reclino, I've heard that too. This one is definetely not bent.
Old 07-31-2020, 10:39 AM
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If it is not bent, then the billet that the valve was machined from was not machined true at the valve head. The slope that starts at the base of the stem and ends at the sealing surface is not symetrical in its thickness. I guess that is obvious, and other than worrying about what else could be wrong, don't know if the out of balance will be an issue.
Old 07-31-2020, 12:24 PM
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r lane, "The slope that starts at the base of the stem and ends at the sealing surface is not symetrical in its thickness." Must be the answer. "don't know if the out of balance will be an issue." I was wondering about this. You can see it in the picture, it's not subtle. Always something, minor/major/unknown to throw another delay in things. I think I'm going to use the lapped valve with the different manufacturing date or site code HC. The lapping was with 320 grit on two seats and the valve face doesn't look too bad. This valve sealed right up to 25 inHg, the max the pump I use can go to by the way, but it just looks so off that it makes me question things.
Old 07-31-2020, 02:19 PM
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Check runout and valve margin. I.e., could you turn it down and end up with a symmetrical valve.

Only if sending it back is not an option for some reason.

Concerns would be thin valve margin, potential to burn or crack on the thin edge.

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Old 07-31-2020, 02:53 PM
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If you can't returned it, just buy a new one. Why have that worry hanging over the motor?
Old 08-01-2020, 11:36 AM
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eastbay,
I know, what sucks is the parts quality and shipping delays, you don't want to know.. I ended up using this outlier one to do the fine lapping of machined seats to bring the heads to high vacuum and good seals, I touched up the worst seat and it seals nicely, I'll move onto the last 4 heads. I had six "normal" valves, I had used one of the more normal ones to lightly lapp two heads at first. I'm going to use that normal but lapped in valve in the running motor. You see, originally I had seven valves planning to use one as a light lapper, and install the other six non lapped valves, I just didn't pick out the difference at the start.

One other amateurish thought comes to mind beyond balance, that's the thermal characteristics of this valve that has more material on one side than the other but otherwise has no real issue. I have no idea if one side of the valve will always be a little cooler than the other with something like this, maybe long term it might make a microscopic difference, in any case, I could have used it but didn't.

One other thing, after a closer check, all valves will obviously have some delta between min and max face width but this one is about 4 times worse than any of the other six.

Phil

Last edited by ahh911; 08-01-2020 at 12:28 PM..
Old 08-01-2020, 12:20 PM
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Does anyone know how deep the stellite coating is on the exhaust valve 45 degree face?
Old 08-01-2020, 07:42 PM
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If anyone is interested, the reason why there is an offset is this:
The valve head and stem are made of different materials and mated together. Each part is pre machined/formed prior to mating. The mating process was offset in this case. (Usually when you run your fingers down the valve stem towards the head there is a different radius where the two halves join but they are centred on each other.) Once they are mated, then the final cut on the 45 occurs. Hence the offset and different face depths.

Also, TRW website claims these exhaust valves face are stellited, they sure don't feel hard to me, I scratched the face with the edge of a small screwdriver and it easily left a mark you could feel. Not scientific, and maybe it's harder than the material would have been without treatment, but anyway.


Old 08-03-2020, 07:47 AM
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Valves don't rotate, at any appreciable amount if any, so rotational balance isn't an issue. Since the valve head is welded onto the stem, the head may not be perfectly symmetrical. That's a QC issue. Any sealing error can be corrected when the valve face angle is ground relative to the stem axis. Any error you see (as in the photo) is unfortunate, but should be superfluous in operation. There could be a few grams of excess material, a significant issue in some applications. If so, this could be machined and made concentric. However, that's not a good sign of a well-made part.

Perhaps next time, perform your own QC inspection after purchasing new valves. Reject the ones that show excessive valve head runout in the drill press, lathe or drill motor.

Sherwood
Old 08-04-2020, 05:56 PM
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Sherwood, I agree, I don't think balance is an issue. It's the stress difference seen across the valve head, I would think that over time this head may start bending in the direction favouring thicker material, given the heat and cooling cycles, but if the material in the head is robust enough it may not make a difference. It sealed perfectly by the way, and I used it for lapping many heads and then I ran some tests on it when I was done as it was not being run in the car, I have six other good new valves to use.

Phil

Old 08-04-2020, 07:17 PM
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