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Is there a rule of thumb regarding the metal seats that sit under the valve springs on an R69S head? I have dis-assembled several sets of heads to find some springs have a thin stamped sheetmetal seat, with some "bakelite type" washers/shims. Other spring seats are about twice as thick and look to be machined,not stamped, with no "bakelite" washers/shims. Could somone explain this variation? year model perhaps? Can i re-assemble using all "thick" seats and trash the thin seats with their "bakelite" washer/shim set up? Thanks for your time/knowledge, Kevin

oK, so far i've been told that the thin spring seats with the bakelite washers were an attempt at isolating the springs from heat. More importantly that late model upper and lower spring pockets (terminology per Maxbmw) are interchangable on my R69S heads. And finally, that the late model upper spring pocket will fit my valve collets when converting to a rotating valve. Has anybody had any real time experience with this? All i'm trying to do here is convert to rotating valves, but can no longer find a source for the /2 upper-lower spring pockets.

Where have you shopped? Between Blue Moon, Vech, and Bob's, somebody should know where you can find them.

That is correct, Vech's got the goods. He even has the fibre washers. I'm a non-purist with a pile of late model parts; if the part fits, retro-fit it. After some measuring.

I have converted dozens of BMWs over to rotating valves. We had to in the olden days.

However, I think Vech the expert on what is available today.

Thanks Duane, your input is always appreciated.