So in my ongoing build I had similar issues with the heads (817) someone installed BB Springs because it appears they took out about 0.30 during the grinding of the Heads, so those BB springs were 0.250 oversized, I ordered 3359 Springs and 3359B Retainers from Show Cars, but because the valve/head work that was done and the 0.30 material removed, they did not want to stay in there and geometrically would want to slide off the valve, which might make a guy think they were loose and want to over tighten them, who would want them loose?, well we believe my solution is going back to Show Cars and ordering 0.30 shims, Bruce @ Show Cars stocks a 0.30 and a 0.60, shim, so I am running a 0950 Cam, stock springs that match that Cam, 0.30 shims, this should be the fix, I will let you know if that works, but sounds right to me. Everybody who owns a craftsman tool box is certainly not a 409 guru, but you have some great guys on here, just feed them the info they are asking for and you will see through the mystery, I have had some great help on here for sure, so with mine we are per Bruce and a few others setting our spring height at 0.168, which should be the correct height. Spring pressure should be in the 100-120 range from what we were told. We are also installing all new lifters to be sure and I agree it sounds like coil spring binding is your issue also, good luck......... P.S. I was told by several folks including Bruce, they never used a shim in the 409/340 817 head, and that is true, but you have to add all the findings to get to the the total sum of the problem, mine being and extra 0.30 was removed, so it makes it a valid piece of information to get it back to as the factory built/intended it. Also I spoke to Don this morning and he explained it very well, just because you take a BB spring and make up that 0.30 of lost material, then you may not have the correct spring pressure, very good point I would say.
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