Help With Valve Clearance Specs

[MJTru]

Roflmfao. GTSBoy. I work with lots of japanese cars in freeport bahamas. I also work with lots of germans and yanks at my work place FCP (freeport container port) Its funny to be able to do both, but I totally understand your point. As I always hear good comments from both sides.

That was classic as I hear it all the time. Its funny how each person from a different place knocks the other system. But are advocate to the system they learned.

[GTSBoy]

But ignoring that aspect, one system makes sense (ie, is self consistent) and one system is based on random factors and makes no sense at all.

For example. Torque. All SI torque is expressed as Nm. Really small torque you just call it milliNm or 10^-3 Nm or micro or nano or pico and the same going up in the opposite direction. Here, it's ft.lb (or lb.ft for those who don't even understand their own system!) and then for small torques you drop down to inch pounds.....but there's a factor 12 in that conversion. I guess that if you want to go to really small torques, rather than do anything else, you'd change from pounds to ounces, and there's a totally different factor of 16 there. So ounce inches are numerically similar to ft.lbs but not quite. But here's the kicker. Pounds and ounces are not even units of force!!!!! Except that it is, Except that it isn't. Except that it is. But it isn't. Because it is used for both, but no-one ever specifies which they actually mean! So when an American says to me "60 pounds of air", they're probably talking pressure, meaning psi, but they never say psi, just pounds, and of course anyone from the rest of the world expects a pound to be a unit of mass. It's no wonder they crashed that probe into Mars a couple of years ago. The European rocket scientists and the US rocket scientists were lucky to even agree on a launch velocity.

That is the pattern of every single unit in the entire system. Everything plays by its own rules and to hell with the rest.

[StevenCJR31]

I thought shims had a hard coating on the outside that was very thin and easily rubbed thru with sandpaper, therefore exposing the soft metal underneath?

[doo doo]

I understand that the case hardening on nissan shims is about 0.02mm and rubbing them back is not a great idea- hence swapping them around to to help get correct clearances rather than rubbing them back. Precision Shims Australia (in Melbourne) do shims with about 0.2mm case hardening and come in increments of 0.02mm, so can be rubbed back 0.01mm no probs. And they're almost half the price of nissan oem. I get new shims from there almost every time I do a head as the standard ones taken out are usually pretty mushroomed anyway.

[GTSBoy]

With bucket over shims, it doesn't matter so much if you remove the hard layer on the top side because the load is spread across the whole shim face. Putting the rubbed side down on the valve stem is less good. But I do otherwise concur that it is better to get new ones than linish old ones.

[StevenCJR31]

What are the precision shims worth?

[MJTru]

GTSBoy you mentioned that you have done the sand paper method before. ??

How did that work out for you. Is the motor still running. Do you also agree that the first .002 mm is hardened material. ????

Never the less if the shims were sanded down what might be the effects of doing is. On the valve train this is. I had some extra shims and cut one in half, but it all seems the same to me.

Do they mean the shims are treated to be harder.???

Can some one also post a link to were I can find custom shim made at spesific sizes.

Thanks.

[Ben C34]

I understand that the case hardening on nissan shims is about 0.02mm and rubbing them back is not a great idea- hence swapping them around to to help get correct clearances rather than rubbing them back. Precision Shims Australia (in Melbourne) do shims with about 0.2mm case hardening and come in increments of 0.02mm, so can be rubbed back 0.01mm no probs. And they're almost half the price of nissan oem. I get new shims from there almost every time I do a head as the standard ones taken out are usually pretty mushroomed anyway.

I havent heard of case hardening ever being that thin. usually it is around .2 and surely .02mm would be pointless as case hardening. Unless it was .02 inches thick

[doo doo]

^With the .02mm case hardening- Just what I've heard after looking at options to replace oem shims (after finding out the price of oem I was looking at rubbing down the stock ones I had..) Chris at precision shims is a good bloke, happy to chat with you about what you need. All sizes/prices/contact details etc are on the website www.precisionshims.com.au Not sure of other places that do custom/aftermarket shims.

[GTSBoy]

GTSBoy you mentioned that you have done the sand paper method before. ??

How did that work out for you. Is the motor still running. Do you also agree that the first .002 mm is hardened material. ????

Never the less if the shims were sanded down what might be the effects of doing is. On the valve train this is. I had some extra shims and cut one in half, but it all seems the same to me.

Do they mean the shims are treated to be harder.???

Can some one also post a link to were I can find custom shim made at spesific sizes.

Thanks.

Alfa Romeo engine, last century.

[MJTru]

Ok I just finished up the valve clearance on my build. Sorry it took so long I was waiting on a new crank.

Well what was good about the whole thing is once I mesured tye first time and found how much I had to take of the shims I only had to install the cams once and they all came into specs.

One of my questions is. I noticed that some are just a bit off eather a little slack or a bit tight no more that .001 will this be ok.? I have them on a big peace of card board. Check the attached. Its a little getto I was planning on cleaning it up and posting it but im feeling sleepy. Lol.

The exhaust side at the bottom is the finishing measurements. T under the numbers means tight. Im hoping this is ok. ???

Edited June 6, 2014 by MJTru