If you are going to rebuild the engine, a few more measurement tools may be needed…But if this job will be limited to replacing the valve-stem seals (is it burning THAT much oil?) you can easily get by with the $25 calipers…A visual inspection of the camshafts will reveal any abnormal wear, no micrometer needed…Just carefully inspect the tops of the cam lobes…They should be smooth, polished, with no pits or drag marks. That’s it, move on…Don’t worry about the “dimensions”…Once you start down that road, you might as well just buy a factory long-block and be done with it…If the valve clearance is set with shims, those shims will be marked as to their thickness…You can swap them around as needed, then, at the end buy the few you may need…You will need a set of feeler gauges to check that clearance…They usually make a tool to depress the valve and change a shim with the cam in place…
I can’t see the expense of costly measuring tools being justified for the occasional DIYer.
An inexpensive caliper should work fine if measuring valve shims. You might consider buying a set of GO-NO GO feeler gauges for checking valve lash, etc. These blades have steps on them and will tell you very quickly what the spec actually is by simply inserting one or the other and the thickness of any needed shim can be easily figured out from that.
The feeler gauges won’t do anything as far as checking cam lobes of course.
“If the valve clearance is set with shims, those shims will be marked as to their thickness…”
I was already in there not too long ago and had four of the 16 shims removed and out of those four one had it’s numbers worn off to the point that I couldn’t read it so I’m definitely going in armed this time with a decent measuring tool. And plus I suspect that the shims can wear down, at least a little after 170k miles, so the numbers might be a little misleading.
You can swap them around as needed, then, at the end buy the few you may need."
Exactly my plan. Been planning this project for over a month now.
“They usually make a tool to depress the valve and change a shim with the cam in place…”
Couldn’t find that tool to save my life but made a push down tool that may or may not work. Most likely won’t matter though because I hope to change the discs when the cams are off the head.
You must make the clearance measurement with the cams in place and torqued down… The shims are VERY hard material…The markings may wear off but they are dimensionally stable…You insert them with the markings DOWN to protect those markings from wear…A trip to the local bone-yard to glean a handful of those shims might be worthwhile…Call first…
“(is it burning THAT much oil?)”
It burns a good amount (10 – 20 seconds) when it’s first started sometimes and also just from daily driving. I’m not 100 % certain that the seals are the cause. The only other thing that I can think of is the oil control rings might be letting oil past. And I definitely don’t suspect the compression rings because the compression is higher than what the OEM manual calls for.
I’m praying it’s just stem seals and not worn valve guides or worn valve stems.
“Camshaft wear is usually quite obvious. Im curious as to what results the OP desires beyond setting the valve train clearance.”
Just wanted to do a quick inspection since the cams would be removed.
So it’s not very common to have to replace worn out camshafts in a high mileage engine?
Cars do not wear out one part at a time, ESPECIALLY engines…The designers strive to have the entire package wear out at an equal rate…A puff of smoke upon start-up is usually valve stem seals and it’s usually not worth the effort to fix it…Oil consumption is not effected much by this…
Once you start tearing engines apart, measuring things, you are drawn into the rabbit hole and you wind up replacing EVERYTHING that moves…KKAAAaaaaCHiiiing $$$$…
Does your engine use roller rockers or do the cam lobes ride directly on the adjustment shims? Manufacturers have gone to rollers to minimize wear in this area. The steel against steel scuffing in older engines was indeed a troublesome area for wear. Motor oils required special EP additives to keep these engines alive…Today, most of these additives have been removed to protect catalytic converters, deemed more important than protecting against engine wear and manufactures have switched to low-friction roller valve gear…
“Does your engine use roller rockers or do the cam lobes ride directly on the adjustment shims?”
The cam lobes ride directly on the adjustment shims.
“.A puff of smoke upon start-up is usually valve stem seals and it’s usually not worth the effort to fix it…Oil consumption is not effected much by this…”
It’s not so much oil consumption but the oxygen sensor getting coated with oil residue that worries me.
Oxygen sensors will tolerate quite a bit of oil smoke…When the engine warms, the sensor is self-cleaning, temperatures are very high and any residue will be burned off…How many miles before it needs a quart? That’s more important than a puff at start-up…
A trick to limit smoke…Switch to synthetic oil…Synthetic base oils produce very little smoke when they burn…
Back to the original question. I retired as a quality assurance supervisor at a factory. We used Cen-Tech micrometers all the time. We chose these because they were cheap, when you have tools out in the open and subject to theft, you don’t go high end.
cont.
These were checked monthly on a set of level III standards that were traceable back to NIST. I can’t say that they were quite as durable as the Starett micrometers the engineers used, but the engineers mics were not subjected to as much abuse. Used everyday, all day, these held their calibration on average for just over a year. Some guys would take care of them and those lasted longer.
“How many miles before it needs a quart? That’s more important than a puff at start-up…”
I’m not sure about city driving but last summer I took a highway trip that was about 450 miles at around 60 mph. If I remember right it was about a quart low when I arrived. This was before the compression issue was fixed so I don’t know if it would burn less now for any reason. It kinda seems logical though because fixing the one cylinder’s compression brought up and evened out all the cylinders’ compression. No clue why that happened. I thought they were all mainly independent of each other, separated by their chambers.
You think the seals are the main reason this car burns oil, even at highway speeds?
How did you fix the compression on one cylinder?? Wait! Adjusted the valves? This story is getting better all the time!
We are heading towards that Rabbit Hole I was talking about…
What do you mean?
To texases:
You were correct in the absolute but I replied in the context of this thread, that being a discussion of a low cost measuring tool but updated my post accordingly. I worked at two different jobs where I had spent some of my time making sure that the measuring tools used in my own and the department’s endeavors were calibration checked at least yearly. A new measuring tool was suitable to press into service if it came on request from the manufacturer with an initial calibration certificate, good for the first year. After that it would be checked yearly by an outside metrology maintenance service. Without a current calibration certificate traceable to NIST, formal use of any measuring tool, whether it was a micrometer, a voltmeter or an oscilloscope, was not permitted.
If I remember correctly Caddyman, the tight valve may have been referred to another post and involved an intake instead of an exhaust valve. At least that’s a plus because if it was an exhaust there would be problems looming in the future for sure. Knock on wood at this point.
Mystic, I would advise that you not overanalyze things like cam lobe height and things of that nature. A Cen-Tech vernier caliper should be accurate enough to handle most measuring needs.
Are they dead on? Likely not, unless it’s an accident but it will be close enough for day to day automotive needs.
Being off a thousandth or two from the given spec on valve lash should not be a problem anyway.
Wha Who?-
I see what you mean, for a job where accuracy is critical calibration is a must. This seemed to be more of a hobbyist kind of thing, checking stuff out of curiosity, so I wouldn’t worry about calibration. If the cam is worn, it’ll be WORN, no fine measurement needed.
Micrometers are a precision measuring instrument and Harbor Frieght sells “salt water salvage” low end tools. You are measuring a precision part of an engine.
Your answer is no.
Caddyman, did you happen to notice the ad for the vernier caloper in the ebay ad you posted? The ad shows a AA battery being measured. Consider the efffects of shorting out that battery with the caliper jaws. Not too bright. But of course, why would someone need to make such a precision measurement of a battery?