Odd bent valve question

[theunz]

I would, at a minimum, have a new valve and guide installed in the offending hole. Doubtful that there is any piston damage. Shifting at 3500??? Good lord, it's not some British tractor motor. Mine just starts to pull and sound good at 3500

[greydog]

I'm thi king the same direction Mike.
Does anyone have the wear limits for valve stem and guide on an R16?
Dan

[JT68]

Dan, Suggest you get a proper valve job. If you floated a valve at 4k a few of the springs MUST be tired. Not that uncommon. The shop can properly check your spring pressures. Most springs will be fine and just need a shim. Would not recommend just replacing one valve&guide&spring as a band-aid. There are almost always other tired valves/spring/guides when you have a valve issue.

Best, j

[greydog]

Makes sense Jim. Thank you for your input.
Dan

[keith0alan]

Check all of the valve springs for strength. I use my drill press and a bathroom scale to compress them to a fixed length. Any that are under in strength get replaced. I weak spring can cause valve float problems.

[TurboRagtop]

“I have not miced the stem to see if out of round but my guess is that the guide is worn a bit and if the bend is aligned with the wear areas of the guide bore, it will slip in but as the bent stem is turned in the oval bore, it binds in the narrow direction of the bore. Oddly, both heads have the same thing. Time to get out my mics and start measuring.“
Good idea, having accurate guide bore data will point you to the cause of the issue. I would not assume the guide bores are round, top to bottom. The engineering term is Cylindricity; and it is critical that the guide inside diameter form a near perfect cylinder that is concentric and perpendicular to the valve seat. There is side loading on every valve, even with shaft mounted rockers, so the guide ID gets worn oval over time and with the millions of cycles they suffer, cold and hot.
If this were my head, I would do a full valve job, replacing the guides: intake and exhaust. Find a shop that has a SERDI valve cutting machine as they are excellent at establishing the critical relationship between seat and guide.

[greydog]

Thanks for the suggestions. I like the bathroom scale/drill press idea. Readings may not be as accurate as a "real" valve spring tester but it seems like it would be just fine for purposes of comparison.
There is a ding on the valve, in the area where the stem necks down slightlint and the fillet at the bottom of the valve head. There is also a small chip out of the guide.
That makes me think the valve "stuck" for some reason since it's my understanding that valve float occurs at maximum valve extension.
Anyway, the fix is the same...send 'er out for a valve job.

Thanks all.
Dan