Look what I found on one of my VVT heads. Look like someone lost a shim at some point. Wonder how long it was run like that.




Also see the interesting wear marks on the shims. Is that normal?

 

Is it possible that it just didn't need a shim to be in spec?

 

Nope. There is a big gap. A shim is needed no matter what. The bucket is taller on the edges to fit a shim in.

 

That doesn't look like it spat a shim while running to me, there's nowhere close to enough damage. I managed to lose a shim while replacing valve springs (basically from turning the cam by hand while not having it bolted down all the way) and even that was enough to gouge up the edge of the cam lobe and the bucket noticeably.

The wear pattern on the shims looks like there was dirt in there. How do the cam lobes look?

--Ian

 

Cam lobes look fine. I can check again.

Can I just flip shims over?

Based on the history of this motor im not overly surprised that its missing. Just annoyed.

 

Scratches on the remaining shim don't look right, and that thing would be torn up if it was run like that. If I had to guess I'd say I think someone already robbed a shim out of that head.

That sounds like a bad idea but I have no data to back it up.

Also, go buy yourself a tube of Amsoil assembly lube, thank me later.

 

Nope. This motor ran until i opened it.

It developed rod knock so I got it.

 

Then there would be a shim loose under the valve cover, no? Also, see Ians comment above.

 

did you get 1700's or 2000's for when we finally talk you into e85 and allofit?

also SUB's are probably a good idea to protect you from those 6th to 1st shifts

 

Who, me? ID1k.

I want SUBs simply because with my fancy *** head and aftermarket valves the shims I need are right on the edge of the range offered for the OEM SOBs. Most of the ones in that range are NLA according to Mazda and I've not been able to find a 3rd party supplier. The SUBs are compatible with any number of shims from any number or suppliers and are offered in a HUGE range, and because they don't touch the cam they don't need to go through the same hardening process so they are cheap as ****.

+1 for SUBs. I'll probably be converting some time this winter while the engine is out.

 

No, aidan. He's got a 6758 to max out

but you too I guess

 

Oh gotcha. I keep forgetting how inadaquite my turbo is

 

Naw. just id1ks. I do have an oldschool FM secondary fuel rail manifold sitting under my bench though....

thought about sequential flow force. just to annoy you.

My guess is that the motor was running without the shim. No other explanation.

Took apart the other head. Same scratches. Here are pics of the cam too.








And take a look at this. The black spec. It is actually a small hole. Nothing in it, not marks or scaring really. Looks like just a casting hole or something. 2 of the caps had this.

 

Oh and I found this stuck in one of the heads too. Not magnetic.

 

Oil plug crush washer?

 

So when I spat out a shim during assembly, my cam lobe looked like this (the one on the left):



That's from ONE revolution done at a speed of, oh, I dunno, 10 RPM maybe. If your head had spat a shim while running it would look a hell of a lot worse, if it's missing and nobody's opened the valve cover, then you must have had a visit from the valve shim gnomes.

The cam lobe on the right is the one that had weird wear patterns, which has been suggested to me came from dirt in the motor. I dunno, but I replaced it. The bucket was nicked too, it looked like this:



You couldn't actually get a shim into the bucket afterwards because of the nick. I just filed this one down and it's running fine now.

WTF, Mazda is NLAing the valve shims? That sucks.

--Ian

 

I'm at a loss.

Only thing that could explain it now is that it somehow came out in transport, and then fell out again when the motor was turned over, which is has been a few times.

Maybe its stuck in @turbofans garage, from borrowing the valve cover a few times.

If Mazda really is NLAing shims im definitely going subs.

 

With how many of these shims are scratched up, and the fact that I can definitely feel the scratches with a fingernail means I'm going subs.

I don't want to deal with buying a whole pile of new shims, and maybe have them not available again.

 

Lol "just"

 

If you search on here there is a link to buy Nissan shims that work for much cheaper then Mazda.