Valve shim, no markings, odd sizes?

First time valve shim mechanic here...

I have the shims out, but none of them appear to have numbers. So, I bought a micrometer so that to measure the thickness.

The store I bought the micrometer from did not have a metric one, so I bought an imperial one that is accurate to 0.001”. I measured all of them to get their sizes,and then converted to metric. Some of the sizes seemed normal, 2.45, 2.6, etc.. but others were odd. 2.62, 2.54, 2.51.

So, can I have an experts opinion on this? Why would the shims have no markings, and why would I be getting sizes that don’t seem to be for sale?

The shims don’t look custom manufactured. They appear to be made from 2 pieces of metal that are sandwiched together, and on one side their is a smaller circle of metal different than the metal around it.

I could simply round the current shims to a logical number, and then calculate new ones from there. But that doesn’t really solve the problem of why these shims have no numbers, and why they are odd sizes.

I think maybe my next step should be taking one or two to a mechanic, and having them measured to make sure my measurements are accurate.

My current gaps are...
0.15
0.13
0.13
0.05
0.10
0.10
0.09
0.10

My respective shim sizes according to my measurements...
240
245
245
251
260
262
262
254

many shims have no markings
yes go to the nearest number
dont worry about inconsistencies that minor, its in the tool
the mechanic has a inconsistent tool too :woohoo:

The shims are made of one piece, the small round circle is where it rests on top of the valve stem.

The 'odd' sizes are actually very useful.

It's not unusual to see small variations in the thickness of shims - a worn 2.50 shim might measure 2.495 whereas a new shim might measure 2.51. Having an assortment allows you to get shim clearances all as close to one another as possible across each cam.

I use a micrometer to measure all my shims - then I write the actual thickness on the shim before storing in the shim box.

steell wrote: The shims are made of one piece, the small round circle is where it rests on top of the valve stem.

Steve...you naughty boy

Cool. Thanks for the info. I had not looked at Shim #1 closely until this morning as it will not be replaced. It indeed was made of one piece. After I rubbed a little harder to remove the more set in oil I could see this.

It also faintly has numbers on it, though very faint, and could not be read without a micrometer for reassurance anyway. The others definitely not have numbers.

For whatever reason I was placing the shim inside of the bucket, and then lowering the bucket back into position. It wasn't until the last two that I decided to place the shim in position on top of the valve, and then lower the bucket.

Either way everything seemed to fit back together fine, though I am not at a point where I can take new measurements yet.