Quote:
Originally Posted by SaltyNC
Matt, thanks for taking the time to provide the additional info. Really appreciate it. Can't wait to see where your build is going next.
Salty
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My pleasure! Happy to flap my gums about this (obviously); hopefully some of it is even useful to the community in general.
Weekend update: initial valve clearance set on the bench.
Took longer than I'd hoped, but I got a reasonable result:
View post on imgur.com
I wasn't happy with intake 5B but left it just in case I didn't have enough of any specific shim size.
(Note the empty slot in the shim kit in the first photo...
)
But with a target of 0.25mm lash for both intake and exhaust, being inside -0.013mm/+0.029mm ignoring 5B (and still inside -0.021mm/+0.029mm including it - basically +/-11%) I feel like I did alright. I was planning to err on the side of loose, because I don't want to burn a valve; after talking to Minos at Achilles today, I'll be re-shimming the loose (~.279mm) valves to be slightly tight. The 0.04mm increments on the BMW shims is irritating but Minos' advice is that leaving more lash makes the shims more prone to jumping out of the buckets due to the more aggressive cam profile and the stronger springs, and that .22mm (but of course as close to the .25mm spec as possible) is fine for the Schrick 288/280 cam setup. Going down one shim size for each of the valves currently lashed to .279mm should make them all ~.239mm, which should be fine.
Some things I learned yesterday:
(1) The used valve cover I bought rocks on the head exactly like the other one did. I am officially afraid that there's something wrong with the top of my head.
(2) I totally, totally forgot about the fact that the cams aren't currently connected the timing chain. Valve-valve contact between all four #1 valves. Little surface marks but no real damage as far as I can tell, but
that sucked so hard. Scared the living hell out of me.
(3) Using a cheap set of digital calipers sucks for this (I noted +/-0.02mm variance in measured shim thickness, which led to a lot of hunting around for the correct substitute shim... ugh). Ordered a good "absolute origin"-based set last night and hope they make the lash setting easier when I install the head... which is actually my next task.
I'll document the cam removal / installation procedure I'm using when I assemble the short block, also, since it seems to work well (fingers crossed) and is safer than the current how-tos without buying the BMW tool that wouldn't work with aftermarket springs / cams anyway.