Any tricks for checking valve shim clearance?

[atchbo]

Hello. I've read a bunch and am now tearing into my old GS400 to put some new seals in etc and now that I've got the valve cover off, I'm trying to check the clearances on the shims. None of my feeler gauges will fit in any of the spaces (down to .002"). I'll have a look at my gauges to see if I can do this in metric.

Being up in Canada, it might take a while to ship shims back and forth, and the dealerships are always expensive. Any suggestions for how exactly to measure (techniques)? I'm thinking I'll have to take each shim out individually, write down the number, and put it back. Then, aim for one or two sizes down on each one and install them one by one. Sounds like a slow process when you include the postage.

Atchbo

[Nessism]

I suggest you look up GSR member Ghost, king shim guru and manager of the GSR Shim Club, and ask him to send you a thin measuring shim so you can get some proper measurements. Install the thin shim and then calculate what shim you need based on the measurements.

Good luck.

[focus frenzy]

I use a reference shim, it is the thinnest I could find (2.10) and on valves that are below minimums I swap in the reference shim and use the feeler gauges to find the gap and calculate the correct shim needed.

for example: if with the reference shim I have a gap of .40 that would total 2.50, specs call for a gap of .03-.08. a 2.45 shim would give a clearance of .05 right down the middle.

[BassCliff]

Hi Mr. achbo,

I would suggest getting a metric feeler gauge set. Hopefully you can find one at a local auto store for not a lot of money. It makes doing the math much easier.

Take inventory of the shims you have. You may need a digital caliper or micrometer to measure the shims themselves if the numbers have been worn off. (Note: Install them with the numbers on the bottom side so that they don't get worn off by the cam lobes.) You may be able to move some shims around in your motor to minimize the number of shims you need to buy, or have shipped from "The Shim Club". Once you've inventoried your shims and noted your clearances, you can "guesstimate" the shims you may need for your next check and pre-order them.

Just about everything you need to know about GS shim-over-bucket valve adjustment can be had be CLICKING HERE. <<<Link to PDF file on my website.

Keep us informed.


Thank you for your indulgence,

BassCliff

[Sandy]

As mentioned you'll need a smaller gauge to properly measure the clearance. If that still doesn't go in but you can turn the shim and bucket easily that means you have some clearance and can probably get away with one shim size smaller. If it's tight and you can't turn it then it's best to use a reference shim as mentioned above. If you phone around maybe you can find a dealer that will just trade you shim for shim. That's what the dealer in Cranbrook does and yes I consider myself lucky for that.

[Steve]

And since you are already thinking that you will have to remove each shim and record the number, send me an e-mail with a request, I will send you a copy of my Excel spreadsheet that helps you do just that, then it will help you figure out what shim you need to have in there. It will also help you keep track of what's in there from one time to the next.

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[Sandy]

And since you are already thinking that you will have to remove each shim and record the number, send me an e-mail with a request, I will send you a copy of my Excel spreadsheet that helps you do just that, then it will help you figure out what shim you need to have in there. It will also help you keep track of what's in there from one time to the next.

.

I did that exact thing on the weekend and need to thank you for the work you did on the spreadsheet. Next time I do the valves it will be a whole lot easier because I won't have to spend time looking for the scraps of paper I thought I wrote the numbers on and can't find.

[bwringer]

Please work in metric, with metric feeler gauges. It's VERY easy to screw up if you're trying to convert inches.

[jabberjoe87]

Is this common for people not being able to get feeler guages between the shim and lobe? When i measured mine the gaps were huge and i got bigger sized shims

[Steve]

Is this common for people not being able to get feeler guages between the shim and lobe? When i measured mine the gaps were huge and i got bigger sized shims

It is more common for the clearances to decrease with time and miles. If yours were too large, it might have been someone who saw "0.08 mm" and set the valves at "0.008 inches" which is WAY too big. That just goes to emphasize the fact that it's better to use metric measurements consistently.

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