Post-adjustment valve issues?

Hey all,

Sorry if this has been addressed; I didn't have much luck in searching. I also apologize in advance that I don't have many specifics at the moment, but I'm at work without my notes from the weekend.

I just got done attempting my first valve adjustment on the KZ, and I'm a little confused. I measured the clearances, bought the appropriate shims to get the clearances somewhere in the middle of the (.08 - .18mm) range, and buttoned the whole thing back up. Most of my valve clearances were too tight, so I bought thinner shims to compensate.

After double-checking the clearances, a few of them are smaller than they were to begin with, a couple now as narrow as .04mm! Another few should have opened up to slightly greater than 0.15mm, but I can't get a .15mm feeler in between any of them.

I'm confident in my original measurements and that I put the right shims under the right buckets. My camshafts were bolted to the appropriate torque (albeit with not-the-greatest torque wrench from Harbor Freight), in the correct sequence, and with proper timing.

Has anyone has had the same experience? Or is there anything I can check before I start taking the camshafts out again?

Thanks!

Make sure you turn the motor over by hand a couple times. If the shims aren't fully seated or there's oil under them, you might not get an accurate measurement.

Also be sure the cam lobe is pointing 180 degrees away from the valve stem when you're measuring.

Thanks for the suggestions, Topper. Over the course of double and triple-checking the valves, I turned the engine turned over several times. Do you think that would be enough, or should I continue to turn it over for a couple minutes continuously and try again?

Happens to me all the time that is why I do not use the shim guide, they are never correct. I measure the clearances then use the next sized shim up or down. That seems to work for me.

I never do any math when doing mine. I just check for tight or loose and go to the next appropriately sized shim in my assortment and that's it.

Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.

It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?

serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.

It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?

possible if they are worn. Another thing: when checking clearances, make sure to only turn engine in normal direction, don't reverse. That can release the tension on the cam chain and let the cams rise up a bit. I have seen that change valve clearances by a couple of thousandths.

serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.

It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?

Numbered side always goes down. If it's worn very much I chunk them in the trash.

sbc1320 wrote:

serfrock wrote: Thanks again, guys. Unfortunately, regardless of any math I did, adjusting my shims seems to have had the opposite effect of what they should have.

It occurs to me that I re-used many of my shims, and I may not have been careful about what side was up -- is it possible that the shims were so worn that putting them back in upside-down caused my valve clearance to decrease overall?

Numbered side always goes down. If it's worn very much I chunk them in the trash.

If the shim is worn enough to trash it, then you probably ought to look for new cams also, I think they are both about the same hardness, so the cam is probably worn also.

Way back when, Chevy let a bunch of non hardened cams get installed in their 350's, cams didn't last very long as the lobes were worn off the cams.

Shims don't wear, it makes no difference if the number is up or down on the under bucket shims. Of course on the over bucket keep the number side down, as the cams directly rub on the shim. Still makes no difference, just so the numbers don't wear. There are really only few possibles, either error in the original checks, error in subsequent checks or the rare possibility of a shim marked wrong. Unheard of back when all shims were factory, now that that the ever popular Chinese shims are the norm, a possibility.

Stop and think this through for a minute. This is a basic procedure. If your lash measurements aren't coming out correctly then you're either doing something wrong or there is something wrong mechanically.

With whatever shims you have in the engine now..... Point the lobe directly away from the bucket so that the tip of the lobe is in line with the valve stem, pointing opposite the valve head..

Check your lash right there. Forget that silly chart altogether. Based on your lash reading, go up or down in shim size to get the lash correct. It's quicker if you have mics or calipers to measure the shim you take out and also the shim you want to use.

Doing it this way, you are 100% assured you are on the base circle of the cam, in a particular spot on the base circle where there should be no abnormal wear influencing your readings. Also, that is the position on the cam where the valve is absolutely closed [providing there is actually lash].

If you try going by the portion of the base circle that is immediately following he opening ramp of the lobe, you can run into situations where abnormal wear will yield a reading that doesn't match the reading you get using the "lobe away" method.

I am wondering how you determined what the shim thickness is for those shims that needed replacing. Did you use markings on the shims? Or did you measure the thickness with a micrometer? I have seen shims with the numbers so faint that the numbers were hard to read. Possibly mistaken a 3 for an 8, or some such thing? I have also seen shims with no numbers at all, so manual measurement was necessary.

One final thought, although unlikely... Is it possible that a previous owner ground some shims down thinner, on the opposite side from the numbers, so that the actual thickness is less than what is marked? This is a bad practice since the hard coating might have been ground through, but it would explain why the clearance was reduced after those shims were replaced with ones that were truly the thickness that is marked. You might measure a few of them to see if they are the thickness that is marked. Just a wild thought.