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Valve bucket wear and clearances


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Hey all,

 

Going through my spare motor pulled from a parts car I bought, and found some out of spec valve clearances. Motor was confirmed 30-40k off of YNANSB with heads worked, and PO verbally stated that that the clearances were reset to nominals. I have no reason to doubt that, heads were flat within .001" (my smallest feeler gauge) and everything else he told me about the car/motor appears to line up.

 

Thing is, 4 valves are out of spec and the rest are borderline, all in the "tight" direction. The buckets vs their marked sizes are worn 2-4 sizes down, per my mic measurements. This is a good thing given the valves grew tighter, I suppose.

 

Questions are:

 

1) I assume that this type of bucket wear is normal after 180k. Can anyone confirm?

 

2) Thoughts on valve clearances drifting out of spec like this after only 30-40k miles? Seems a little aggressive given how recently the heads were serviced. Can I reasonably expect the growth to have stabilized by now?

 

Either way, I'm inclined to reset the clearances to nominal again, by shuffling buckets and finding some new or secondhand as needed. The heads have been bolted to the motor for the clearance check so I'd prefer not to pull them off again to get the valves tipped, unless I need so many new buckets that it justifies the cost of new gaskets and the machine shop fee.

 

 

Would appreciate any insight.

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Sigh. Went to retorque the head studs after they stretched for a bit and the clearances shifted. Would also help if I could trust any of my feeler gauges under .010 - mic'd some as much as .0010 oversize versus the marked value. Lot of valves still off nominal, but only one out of spec outright now.
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Much appreciated. 4 sizes on account of belt tension is nuts - I wonder what the cam bearing clearance is, and whether this gets taken out of the equation once oil is flowing into the journals. Not that Subaru could reasonably expect this to be taken into account when calculating shim sizes.
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