Nope, that would be .016" clearance.
Make sure you are measuring on the thrust surface (front to back, not sides).
Very crude/inaccurate way to measure.

You got it Dennis.

I don’t want to step on any toes here, and I mean no disrespect.  I just want to clear up some obvious confusion.

First, checking piston to cylinder clearance with a feeler gage is a perfectly fine alternative to a dial bore gage and micrometer.  It’s not as accurate, and I wouldn’t use the feeler gage to resize a cylinder, but its just fine for verifying running clearance and also a great cross check of the more precise measuring instruments.  I always cross check with feeler gages after measuring with precision instruments.  Actually, there are spring scales available to verify correct drag on feelers when used for fitting pistons.

Second, Dennisqb, if you can fit an .008” feeler between the skirt of the piston and the cylinder (assuming the drag is proper and the piston is positioned correctly) your piston to cylinder running clearance is .008”.  That works out to .004” radial clearance but you don’t use radial clearance to evaluate piston to cylinder.

As Armen said, you always do this check in the fore/aft direction, perpendicular to the wrist pin.  That’s because pistons are not round, they are egg shaped.  Pistons are also tapered top to bottom, the top being way smaller than the bottom.  So, the tightest clearance is found close to the bottom of the piston in the fore/aft direction.

This picture shows a cylinder/piston combination that has right about .003” running clearance.  Note that the drag on the feeler is just enough to hold the piston suspended in the cylinder, just enough to prevent gravity from pulling the piston down.  The piston will continue down with just a light finger push.

Feeler gages are an excellent alternative to expensive measuring instruments.  Certainly, good enough for the shade tree mechanic trying to do a ring job.
 
Dennis, if your .008” feeler fit between the cylinder and piston as shown in the first picture, if the piston could be pushed through past the feeler with light force, if the feeler was positioned as shown in the first picture, you have too much running clearance.  If you are very lucky, the majority of the wear is confined to the piston and you will be able to tighten things up by simply replacing the piston.  Otherwise, its time for a rebore.

DragBikeMike wrote on 05/20/20 at 12:26:46:


Thank you for the clarification. When I stuck the feeler in there I was at the piston ring position and not properly on the skirt. I did proper measurements at multiple places and got .0025” at the top and .003” at the bottom. That coordinates with my expandable tool and micrometer. I think it’s good to go. I just need to clean off my bench so I have room to work

[quote author=5C676A7D6C607B7D666E637C0F0 link=1589923440/0#10 date=1590254003]Dennisgb wrote on 05/22/20 at 12:46:23:


It’s been really hard for me since my shop burned down last year. I had an awesome workspace then.

Now I’m in a dirty barn with varmits and not much bench space.