Strange valve clearances results?

[LAB3]

OK, let's start by saying that I consider myself to be a pretty bright guy and most seem to agree unless I **** them off. My first career was land surveying so I'd like to think simple addition and subtraction are pretty easy stuff compared to some of the other things I've done with numbers.

In an earlier post I mentioned not being able to measure the clearances on my exhaust valves because they where too tight, my smallest feeler gague (.0015in/.038mm) would not slide into the gap between the shim and cam. Using the zip tie method I pulled and reinstalled each of the shims individually, checking their specs with both reading 2.55

Joined the shim club and passed along this same info. It was suggested that I purchase a thinner shim and thinking toward the future, I chose a 2.30 thinking that might work for at least one or two more checks in the future. Once I knew which ones I needed I could then make the swap with the club.

The shim arrived today and I replaced the 2.55 with the 2.30 on my first cylinder. The gap was .012 in or .305mm. Sure enough, the other one was also .012 in. Good enough, time for a cup of coffee and some good old fashioned cypherin'.

2.30mm + .305mm = 2.605mm.

Hmm, now if that where the case the 2.55 shim SHOULD have had .05mm of clearance and my thinnest feeler gague should have fit in there, yet it was completely tight.

Go back, check the work. Recheck the manual and follow the instructions again. The clearance is to be checked with the cam lobe facing 90° to the cylinder head where the valve cover mates up OR with the cam lobe in line with that same surface. Both positions are offset 45° from where the cam lobe would be pointing straight up opposite the shim. Yep same results!

So, something isn't making sense or I'm not doing something correctly. No, I don't have a caliper to check things so perhaps the old adage "It's a poor Craftsman that blames his tools" may not apply here. Any insight would be appreciated, I'm headed to the liquor store!

[Steve]

If this is on your 450, you can measure clearance with the lobe pointed away from the valve. The directions for the 45° offset are for four-cylinder bikes that have two valves on the same side of the chain.

One thing to be sure of when checking clearances is to make sure you are not trying to put TWO feelers in the gap. Since you mentioned your smallest feeler is 0.0015, I am assuming you have an INCH set with metric approximations. That is not a problem, just make sure that you can see the 0.002 feeler. That way, you will know that it is not stuck to the back of the 0.0015, giving you a total thickness of 0.0035".

Might I also suggest that you take advantage of the offer in my signature? It takes a lot of the effort out of the ciphering.

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[LAB3]

Thanks for the quick reply. The lobe position thing is per the manual and I have checked it with the lobe facing directly away from the shim as well, same results either way. As to the offer of the spreadsheet, I did try earlier to find your email address but was unable to locate it. Things do seem to work different one a phone versus computer so that may be why. There are a couple different sites with online calculators but they won't accept null (0) as a starting gap measurement. If yours works on an Android and can deal with a null input, I'll certainly give it a try. TIA.

[derwood]

you say you don't have a caliper, but it sounds like you measured the shims in your first post. ...
measure your shims, a micrometer is nice

[Nessism]

Maybe the zip tie resulted in a small chunk of carbon lodging under the valve seating face thus increasing the clearance? I prefer to use the standard valve bucket depressing tool and purchasing a few shims smaller than those installed so you can have what you need to move forward in one day. Since you have 2.55's now and not enough clearance I'd purchase some 2.50's and 2.45's. Worst case you have a couple extra's. Z1 Enterprises sells shims for $4.85 each.

[LAB3]

No measurement, was reading the number etched into the bottom. Just got back from a quick trip down to the local marine repair shop, the mechanic there had a caliper! We measured the shims and both the original and new one where dead on, the feelers gagues, although of the lowest cost where also close. Here's what we deduced:

The .0015 inch feeler is .038mm which is a tad over the minimum clearance. The .012 inch feeler is .305mm

therefore

2.55 + .04 = 2.59
2.30 + .305 = 2.605
The difference between them is only .015mm!

So, the 2.55's are probably OK but close to needing replacing anyhow, so if I go to a 2.5 shim I'll be a tad sloppy but won't need to deal with it again for several thousand miles.

Again I'm reminded of yet another old adage, this one I heard from an old school civil engineer many years ago:

"There's no sense in measuring a log to within 1/64 of an inch so you can mark it with a lumber crayon and cut it with an axe" I got caught up in the numbers instead of the application.

Like we used to say "close enough for government work!"

[Steve]

The lobe position thing is per the manual and I have checked it with the lobe facing directly away from the shim as well, same results either way.

I only have the Clymer and Haynes versions of the manual. Clymer does show the lobe pointing up, Haynes only seems to cover the 4-valve versions. While having the lobe pointing up is not exactly wrong in this case, it's not as critical as it is on the four-cylinder bikes.

As to the offer of the spreadsheet, I did try earlier to find your email address but was unable to locate it. Things do seem to work different one a phone versus computer so that may be why.

Not sure how different things work on a phone, but if you saw the invitation, you should have also seen how to find my e-mail address.
Straight from my signature: "Click on my username in the upper-left corner for e-mail info."

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[Motojoe2492]

I'm hoping my valves don't give me as much trouble as everything else has been... Steve, your inbox is full and I couldn't send my latest response, just letting you know!