Valve clearance measuring method

Hi All,
I've noticed this several times and curious what people do and if it actually matters.

For both my 550 and my 750 I sold one manual says to tighten down the cams but no pattern, but the OEM one gives a pattern. I think this may be important. But, the aftermarket manual says to just point the cams 180 away from the buckets and measure. The OEM manual says to have the cams at certain positions on the crank (like tdc and such). Is there really much of a difference when actually measuring them? I wish I found the oem manual on my pc last night BEFORE I measured them the 180 deg way and took the cams out.

There is a small amount of "slop" in the cam bearing surfaces. Some say it doesn't matter some says it does. If you measured with the lobe pointing away, you should have a reading that's good enough unless the cams are bouncing around. The bearing surfaces should tell you that. If not, you're good to go.
Steve
Oh, the idea is to tighten the cams down evenly so as to not get them cocked to one side or the other.

Well, if the bearing surfaces were bouncing around, the shims and clearance wouldn't really be the biggest issue I have, right? lol. All of mine are either right at the spec or too tight, so when I get shims I'll get ones that put me smack in the middle of the clearance spec, so I have room on either side for errors from my measurement or slop.

If you can afford it, get a few the next size down just to have on hand. When I buy mine, I try to pick up a couple extra for next time. Better a little large than too small. You have shim under buckets. PITA to adjust but no worry of "spitting" out a shim. Set them large.
Steve

I just ordered the hot cams kit. It was ~55 online. That way I don't have to play musical shims, and by the time I figure out which one I need and hope its good, I'll spend that much. A pack of 5 of the same shims cost over $6, and I'm not sure I wouldn't have to buy several packs. Plus I do have two 550's and can't rule out not adding more KZ's in the future

Then you have shims galore. :woohoo:
Steve

When you measure by pointing the cams away from the bucket than the adjacent valve will be pushing up on the cam and skewing it in the journal clearance. This method results in your thinking there is more clearance than there actually is while the engine is running. Make sure to adjust the clearances to the wide end of the specification range if you measure this way.

Well that's a good point nessism. Happens to not apply a whole lot to my situation because they were all tight already. I will use the oem manuals method though.

Nessism wrote: When you measure by pointing the cams away from the bucket than the adjacent valve will be pushing up on the cam and skewing it in the journal clearance. This method results in your thinking there is more clearance than there actually is while the engine is running. Make sure to adjust the clearances to the wide end of the specification range if you measure this way.

Thanks. Is this why the factory service manual shows the cam parallel to the cylinder head, instead of directly away from the bucket? I was thinking it was simply a quicker way for the mechanics to do it, using the timing marks to set the camshafts.



apbling, not sure if you did it or if it will always matter, but the manual says to re-torque the cam cap bolts before doing the valve clearance procedure. If those are loose, I would assume there would be some slop in the measurement.

Here's how I record the numbers --- drawing scanned from the manual.

Adjusting per the factory method is faster because you adjust the valves in pairs without having to spin the engine as much. The clearance measurements are more accurate too. Again, you can do it the other way, but always shoot for the wide end of the spec range or even a little over.

Shooting for the wide end of the range has increased the wear from what I can tell, just the sound, alone, tells you that. You can't have and increase in tapping sound and expect no increase in wear.

If it would be better to shoot for the wider end of the range, the designer would have moved the range accordingly. They expect you to aim for the middle of the range, or better yet, follow the manual's instruction on when to change a shim and to what size. Then you are doing what they expect and things happen as they predict accordingly. Trying to make up your own maintenance procedures is a bad idea when it is already spelled out.

Makes sense Lou.
Every single time I use the Clymer book, I like it less and less and less. I have both of them, but the Clymer is a little handier because I have it in my hand, whereas the OEM one I have a tablet I use to view it - I've printed manuals out before and put them in binders, but I always end up ripping pages or I get irritated with the cumbersome binder.

I actually find the Clymer method easier than the OEM method. Don't have to look a the timing marks and such, just rotate it around til one of the cams is pointing away and go with it. BUT, for an extra 5 sec of effort I'll be using the OEM method from here on out.