My recently rebuilt B21F has been suffering from a rough idle. After troubleshooting everything else, it occured to me that if valve clearances were not correct, that could result in this problem.

So today I measured the clearances, only to find that even with my smallest feeler gauge (.010), I still had to slightly depress the valve spring to get it to fit, every single one was snug.

I removed the cam and noted that all the washers are original, and all measure 3.97mm. From a rented shim kit, I put in their thinnest washers to start (not knowing how thin I needed to get). These washers were all 3.30 and 3.35.

I reinstall the cam and remeasure. The 0.10 feeler gauge is still snug but not as snug, so I've made a difference, but it appears I have much further to go.

However, the shim kit I have offers nothing thinner, and I've noticed that if I go much thinner on the washers, my tappets may end up being taller than the washers and perhaps interfere with the lobes?

Am I missing something here? Is it possible to need to reduce the washers this much after a valve grind with new seats? Is there a place to source washers thinner than 3.30?

Cheers,
Jason