Valve Check Mystery

[DezzertRider]

In the process of doing my first valve adjustment, I replaced two shims. After I replaced the two shims and torqued the cam caps down I then discovered that I now have four additional ones that are out of spec

I loosened and then re torqued the cam caps and still have four additional ones out of spec that weren't before removing the cams and and reinstalling them. Not sure how this could happen?

I have the cams in the correct position. T-Mark lined up with case marking and cam lobes for cylinder one facing outward. The small holes on the cams are lined up perfectly with the arrows on the cam caps.

Any ideas?

 

[Fred W]

More details needed.

Out of spec in what way. Which ones exactly. Which ones did you adjust, and what were all the other measurements before and after?

 

[FJRBluesman]

Rotation check error the first time? Cams not aligned properly? More detail would be required. Did you mark the cams at ll or just use the timing marks period?

 

[DezzertRider]

More details needed.
Out of spec in what way. Which ones exactly. Which ones did you adjust, and what were all the other measurements before and after?

I have four intakes now out of spec on #1 and #2 cylinders ( too tight .006 feeler guage does not fit, but .005 does not. Also I have two exhaust valves too tight (.007 does not fit, but .006 does).

 

[DezzertRider]

Rotation check error the first time? Cams not aligned properly? More detail would be required. Did you mark the cams at ll or just use the timing marks period?

I just used the timing marks. Used the T mark and then the II mark and then measured the gaps on the valves where the cams were facing outwards as each mark was lined up.

 

[RaYzerman19]

It's sometimes easy to be off. I usually go through the check twice before I decide on changing shims. Spreads the oil around, make me sure I inserted the feeler ok, just makes me feel better, whatever. So, now that you've got your results, spin it over and do the check one more time. If you had metric feeler gauges, you'd get a little better resolution. I'd also say if in doubt it's too tight, swap out a shim.

 

[Fred W]

If the cam caps were installed wrong the tolerances would have increased, not decreased.

If you screwed up the chain / sprockets it would affect the timing but the clearances would be the same.

Did you remove both the intake and exhaust cams?

Did you remove the buckets over the valves that are now too tight?

 

[hppants]

I'm no expert but the few times I have done this, I have noticed that it is far from an exact science, especially for an inexperienced noobie like myself. I purchased a set of "go no-go" metric feeler gages and that made a HUGE difference in my confidence for the process.

Also, at any given valve check point, rotating the camshaft even 10 degrees can throw the numbers off.

Is it possible that the cam covers were mixed up? #1 cover is in the #2 spot - or any other combination? If the cam bearings are slightly different, the perhaps a combination can be conceived that would put the cam lobe a knat's behind closer than before?

 

[dcarver]

I've heard more than 1 good tech say things can simply change on re-assembly.

 

[Allen_C]

All of this makes it sound like checking your valves is almost a crap shoot!

 

[Panman]

Did you Seafoam the engine? It's been said that carbon in the chambers can have you chasing readings.

 

[Fred W]

I've heard more than 1 good tech say things can simply change on re-assembly.

All of this makes it sound like checking your valves is almost a crap shoot!

I don't get why this would be the case.

Here's a screen capture of the valve adjustment I did on my 1st Gen. I only had to adjust intake valves, so that's all I'm showing.

First I measured my old shims with a cheap Chinese micrometer. Then I had the spreadsheet calculate the optimum shim thickness (to target the 70th percentile value of 0.20mm clearance). Sanded them to that desired thickness using the same micrometer.

As you can see, after reassembly I measured the 0.20mm within a +.01 / -0.0 mm tolerance. I'd say that is pretty good repeatability and reproducability. 0.01mm is about 1/3 of .001"

These "good techs" may not be anal enough about their measurements, or maybe they aren't measuring the shim thicknesses and just assuming they are what it printed on them?

 

[RaYzerman19]

The biggest source of error is measurement with feeler gauges, so best do the best you can at that stage. Taking it apart and reassembly in the FJR's case is quite precise, so there will be very little change from doing that. It is not a crap shoot. You've heard the saying measure twice, cut once...

 

[Spud]

I can only add that with the help of an excellent mechanic brother in law, we did mine, changed 2, and all measurements stayed the same on reassembly except the 2 we changed. I haven't really heard of tolerances changing for no reason other than reassembly. Good luck--

 

[kaitsdad]

The only time I've seen this is when the caps were installed out of sequence. Verify position.

Then verify tolerances again, paying close attention to the lobe positions when checking clearance.

Thirdly, I would suspect that a camshaft bent when being removed/replaced.

 

[MCRIDER007]

More details needed.
Out of spec in what way. Which ones exactly. Which ones did you adjust, and what were all the other measurements before and after?

I have four intakes now out of spec on #1 and #2 cylinders ( too tight .006 feeler guage does not fit, but .005 does not. Also I have two exhaust valves too tight (.007 does not fit, but .006 does).

The question asked was "what were the measurements before and after", the answer was clear as mud and only answered the measurement after on the now tight clearances. There is big difference in a after measurement that changed by .001 or more vs an after measurement that only changed by .0005. I'm also still looking for the answer to whether you changed the bucket positions.

If you want good suggestions then you should furnish complete responses to questions.

 

[dcarver]

Fred said - I don't get why this would be the case.

Me either! I'll followup with the gentlemen and ask more pointed questions like how is that freaking possible?

 

[DezzertRider]

The cam caps are labeled I1 I2 E1 E2 etc. and I placed each one carefully in order when I took them off, so I'm quite certain I didn't get them on in the wrong order. I have ordered more shims so I will see what happens once I receive the new shims and put everything back together.

I only moved the cams far enough out of the way to remove the lifters so I really don't think I could have bent a cam. I only removed the lifters where shims were being replaced. So I'm certain I didn't mix up the lifters/buckets. When I took the lifter off in order to take the shim out, I put the lifter right back in so that any mix ups were impossible.

So I'm not sure WTF happened. Once I get the new shims, I won't be ordering any more. All of my clearance readings have been .001 on the tight side, so I should be able to sand down any additional shims. Once I get the new shims, I'll see what transpires next.

I also replaced the CCT, but I don't see how that could have effected the clearances.

Initially I only had one intake (cyl. #3) that was .001 too tight and one exhaust that was .001 too tight (cyl. #4). Now I have both intakes on cyl#1 and cyl#2 .001 too tight and one exhaust on cal #3 .001 too tight. So including the original shims (two) this makes a total of seven shim replacements which seems to be unheard of for a first valve check/adjust with 26K miles.

In addition, I spun the crank around at least 3 times and made the original measurements multiple times to validate the measurements and ensure I got consistent results before pulling the cams and lifters.

Once I put the cam caps back on, I did the same thing by spinning the crank around multiple times and made the measurements multiple times. As stated before, once I get the new shims back in, hopefully I'll get consistent results this time. Maybe it was the Jameson's Irish Whiskey the night before?

 

[MCRIDER007]

It's pretty common to have a small amount (.0005) of "play" between the cam lobe and bucket and also to have slight variances depending on the position of the lobe. The amount of oil (or lack of oil) on the cam and lobe can also make the difference between a go and no-go and that oil is going to be reduced with multiple measurements. You probably had 5 borderline clearances that were pushed into the tight range by drying the surfaces through multiple measurements.

When I record a clearance I try to distinguish between a tight, normal, or loose fit and use that as a baseline for the next valve check....and yes, it is pretty subjective when working with such small clearances.

Pulling cams is a hassle, if you have to do it then you should go ahead and change every shim that is at the tight end of the range.