Help me diagnose this noise (video)
 

I just got done swapping this VVT motor into my NA.
I bought the vvt motor at a junkyard, per Carfax, it only has 65000 miles. I had the head rebuilt and shaved by 0.030". The machinist did a valve job and he said he cut the valves to set valve lash instead of using shims.
I am afraid this sounds like rod knock. The oil that came out didnt show any visible metal but it may be a bad bearing...this is no bueno.

Have you let it run long enough to warm up? What RPM is that in the video?

You can try pulling plug wires one at a time to see if it is ignition related.

I got the water up to 190f. It was around 1300rpms. It's on the base map I got from Reverant

Mine sounded like that. Bad bearings both times. Trashed rod the 2nd time.

It sounds like less than 1300 bpm - The camshafts run at half the speed of the crank.

It may have been a little less, tuner studio wasn't syncing and my tachometer doesn't work yet

I'm going to remove the valve cover this Sunday and measure valve lash. The machine shop guy ground the top of the valve stems to set lash. I'm hopefully going to find excessive lash. If this is the case, I'll buy the shims from Mazda and do it myself.

I just finished checking valve lash and they all look within spec, except the exhaust valve's lash on cylinder number 3 is 0.014". Still, it shouldn't make that much noise just because of that.
I think it may be the bottom end, which sucks.

I dunno if it's the video, but I see a lot of movement on the exhaust cam. Is the TB tightened? Might be slapping around...

Yea, the tb is nice and tight. I took the valve cover off and the exhaust cam looked good. I'll check the cam retainers caps again

Yea, the tb is nice and tight. I took the valve cover off and the exhaust cam looked good. I'll check the cam retainers caps again

So, found something?

I had the cam cap in number 2 in number 3 and vice versa. No damage to the caps happened but I did forget my wrench in the crank and tried to start the car, the crank bolt came off and messed up a few of the last threads in the crank. I'm waiting on a tap I ordered from amazon today so I can chase the threads, then I will start it again and see.

You think the cam caps were causing the noise? I guess you'll didn't have time to validate with that forgotten wrench...
I have a similar noise on my car, it is in storage right now, but what you find will probably help me.

Thanks!

Ben

I just looked at the Finanza cam and it is touching the metal back cover holy crap. This is probably the cause

Good new if it is only that! I'll have a look at that cover, I know I snapped a few bolts when I removed it a few years ago...

https://www.miataturbo.net/attachmen...ine=1453931275


https://www.miataturbo.net/attachmen...ine=1453931275