I realized my last post regarding valves and valve guides might have gotten a little too crazy with its talk of micrometers and valve guide clearances, so I thought I would do a follow-up post describing the valve guide wiggle test.
The so-called valve guide wiggle test is a very quick and painless way to determine if you your valves and/or the guides need further attention – either yours or the attention of a professional – or whether they seem decent and good for another round.
The valve guide wiggle test is incredibly straight forward.
-With your engine heads completely disassembled (i.e. valve springs have already been removed using a valve spring compressor and valves and guides are free and exposed), clean the valve stem in question with some #0000 steel wool.
-Also give the inside of the valve guide a quick clean with some degreaser, ultra-fine sandpaper, and some compressed air.
-Insert the valve into the valve guide from the cylinder chamber side.
-Only insert the valve stem till it is about an inch or two into the guide. In other words, the valve should be sticking out from the valve guide as it would be during the “open” part of the engine cycle.
-Try and wiggle the valve back-and-forth. There shouldn’t be any detectable “wiggle.”
-If there is any “wiggle,” it should be very minor and there is one more step to perform.
-Dip the valve stem into some engine oil. Reinsert the valve stem partially into the valve guide and try to wiggle it again. This time there definitively should be no detectable back and forth motion. This whole process can be done with a dial gauge, resulting in a much more precise answer; but this post is all about a quick diagnosis for those trying to determine how jacked-up their valve setup currently is.
Hopefully, this helps you as you do your tear down and rebuilt. If you weren’t having issues with your valves before engine disassembly, then you are welcome to pass on buying new parts are swapping things out.
Valves and valve seats are precisely ground to “fit” each other, so as you replace parts you are opening yourself up to the possibility of machine work to get parts to match/seat together correctly.
Of course, give everything a good clean and if necessary do some minor lapping, but when it comes to a working valve train sometimes I think, “if it ain’t broke, don’t try and fix it.”
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