Debris on top of intake valves
 

Is this problematic? I took my intake manifold off and found a little bit of sand, a couple dead insects, and carbon buildup on the tops of my intake valves. The carbon is fairly thick, comes about halfway up the tapered portion of the valve, and only seems to be on the left side valve on each cylinder. The carbon won't show up in a picture. I figured this area is supposed to be completely free of any type of debris, but I don't know. So is it safe to use one of those aerosol dusters? Reason being I don't have access to compressed air.

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just make sure the valves are closed and you dont blow anything into the pistons. you could try spraying some seafoam on them and letting them sit over night after you blow off the loose stuff with air. canned air would work for the loose stuff but isnt going to be powerful enough to blast anything off.

Ok, I'll try that. Thanks.