Valve clearances keep changing

[modok]

The valve tip should be worn evenly if it was rotating, so it would not matter if it did rotate. They usually don't rotate at idle but will at higher engine speeds.

Lifters do rotate at even low speeds. probably 50 rpm at a high idle.
Lifters that have a loose pushrod cup can give you some odd lash variation.
Eaton or the new CB for instance.

I don't consider what he is seeing here as "odd" rather the norm, but we might as well learn something useful while at it.

[mark tucker]

the preload method should put them a lot closer as it counteracts the other lobes&springs pushing this way and that way. and remember the oposing valve spring may or may not be pushing back....only 4 lobes...think about it.and they are not 180 degrees appart....hard for most to visualize without a cam in thier hand. and when you set them the...."normal" way...where are the opposing lobes?? ( no I havent a clue as I dont think they way and have no reasom to do so as I know it isant right .) jt more than likely they are across and the cam is getting pushed back toward the valve your attampting to adjust....wrong...like my spellen

[bnam]

I tried Modok's suggestion today. First removed 3/4 rocker and measured on 1 & 2 and then the other way. Here're the results along with the final settings from a few days ago as well as another round of measurements after I put the rockers back on.

The readings in general went up an average between 0.003" to 0.004". Is this a rough estimate of the camshaft bearing play?

Interestingly, the 2 loose readings on perload on intake for 1 & 3 did not change much with the opposite rocker removed.

Am I reading the Bentley correctly when it says that radial play wear limit is 0.0047" for the cam bearing?

Thanks!
Byas

[Boolean]

You remind me of a Ferrari customer I had many moons ago. Assemble, measure, disassemble, correct, assemble until we had to redo all press fit stuff in the engine just to repair the damage done when assembling the engine 10 times. Or 20.
You are golden. Concentrate on the worn out stuff instead.
_________________
I strive for perfection. Excellence will not be tolerated!
Build thread here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=529379

[mark tucker]

i cant fallow what your saying , but...what have you learned and figured out works best.kinda hard to get them all adjusted with rockers removed....

[modok]

Yeah I don't really understand the chart either.
But, it appears without rockers on one side some valves varied more, and others less, which means.......well, who knows. It means the cam has .003-.004 clearance as expected.

I think if it means anything, it means that the cam does wiggle in operation, and the cam has partly worn to account for that. If the cam was new, and ground on center, there would be no variation in lash, and yet there is. So, if you ran it long enough, then it might wear the base circle so it doesn't vary?

[bnam]

Sorry about chart -- the table in the middle is without the rockers. For example -- First cell is Cyl 1 measure with no 3/4 rocker and at TDC on Cyl1. Intake is 0.008" and Exhaust was 0.007" -- which compares with the 0.004" and 0.007" (top table)respectively from the measurements I had made earlier and with the bottom table which was after I put back rockers and measured again.

Bottomline is that without rockers the measurements seem to add an additional 0.003" to 0.004" on average across the valves. That seems to be a measure of the cam wear -- which is to be expected from a 100K km engine, but within the wear limit per Bentley (?).

I don't drive the car more than a 1000km a year. So, if it is not hugely destructive my thought is the leave the bottom end as is. Adjust the valves to the best compromise position and be done with.

Doing the double reading -- TDC and pre-load gives me a better measure of the variability and is helping me understand what setting gives me best compromise.

Next step -- install engine and get it started and running. My first experience in installing an engine so wish me luck.

Thanks for all inputs guys. While it may have seemed like a lot of work for nothing to you experienced guys, I keep learning from this.

Byas

[mark tucker]

I dont know what tdc adjustment is, but if you found the best way with the least variance then go that way. also difrent valve spring pressures can change the variance....hmm I had to get a variance when I built my shop oh so close to the property line....and ..according to the surveyers it was ...to close for the county so i had to move the entire shop(34'x24') just a few inches witch is...eazely done.... on the survey. witch proves your not done till the paper work is done.

[74 Thing]

Set them all at .004" and be done with it. Just check them once in a while.

[mark tucker]

just make sure your method is the same on all valves and each time you do it including the temp that you do it. I do mine warm at zero lash.