QuicK: Valve Clearance measurements changing?

[Poot]

Hey all,

I've done my clearance for the last 50000km, and have a weird "problem" now where my readings are changing on me (dead cold engine)


I had one valve with clearance greater than .102mm (tolerance is .03-.07), so I swapped the 2.55 that was in there for a 2.6x shim, too tight......swapped in a 2.6 shim, still tighter than .025mm!!!


How the heck could this be? I've turned the engine over a few times, and it didn't change the reading, so it seems like it would need me to put another 2.55 right back in. But that just doesn't make sense that I would put the same size shim that was originally giving me way too much clearance.








POOT

[Poot]

just a side note.....I'm checking, and have always been checking my clearances with the lobes perpendicular to the engine (a la clymers). maybe I should change my technique? Still wouldn't make sense, as I should get the same readings.

[rudy]

Was the 2.55 that you pulled out originally actually 2.55? Do you have a means of measuring? Printed numbers can lie, but the micrometer doesn't.

[Nessism]

just a side note.....I'm checking, and have always been checking my clearances with the lobes perpendicular to the engine (a la clymers). maybe I should change my technique? Still wouldn't make sense, as I should get the same readings.

When you check the clearance using that method the adjacent valve will push up on the cam and skew it in the journal clearance. The proper method is to adjust per the Suzuki method which puts adjacent valves on the base circle in pairs.

Not sure how much difference it will make but I think you will have more consistency measuring per the factory method.

[Steve]

I used to check clearance with the valves pointing away from the valves, but have since been educated into the Suzuki method. Took me a while to really understand why the Suzuki method is better, but now that I understand, I am more comfortable with it.

When the cams are aligned according to the factory manual, the two cam lobes on that side of the engine are at about 45 degrees to the valve axis and neither one of them is pushing on a valve, which might bend the cam ever so slightly. With the cam in this neutral position, check the clearance on both valves before adjusting as necessary.

I had a problem believeing that the cam might bend with just valve spring pressure deflecting it, but it just pushes the cam off-center in the oil film in the bearing.

.

[Poot]

I just used the suzuki method, and it sure is a lot easier (though the measurements seemed the same/pretty close).

Strangely enough, I just put in another 2.55 and the clearance is in between .051 and .076.


All good for another round !

thanks all.



POOT

[Roostabunny]

I used a digital vernier calipers the last time (which was too long ago, as I admitted in a separate thread) and I was shocked at how off the printed numbers could be. In fact, the mechanic who let me swap shims used the numbers to sort, but he still measured every shim to double-check.

As an aside, I used those measured dims to record my shim sizes, so regardless of the printing, I know what's in there. When I check clearances later this week I'll just take my measurements and I'll know what sizes I need on which valves.

I also use Steve's valve adjust spreadsheet, which sped up the process for me and keeps the record handy between adjustments.

[Roostabunny]

I used to check clearance with the valves pointing away from the valves...

I tried it once with the valves pointing toward the valves, but I caused a rift in the space-time continuum that totally screwed up my measurements.

End result: I ruined a perfectly good set of feeler gauges that now only read in ounces.