Hi,

What is the best way to change shims on an NB2 without the Mazda special service tools?

As I am hoping to swap some shims around to minimize purchase of new ones it may be easiest just pull the cams up. Is it possible to leave the timing gears attached to the cams and zip tie timing belt to timing gears to minimize reassembly work? May not work as once you lift the front cam cap it will need the cam seal to be replaced which needs to be done with cams installed? Just thinking out loud. Any advice appreciated.

Cheers.

 

this is one of those if you have to ask and I mean that in the nicest way possible. Meaning, if you ask how it's possible to do with the cams in place, you're likely to damage the cam, head castings or buckets in the process. Fwiw the easiest way is removing the cams. Any tools that you see for other cars do accomplish this (mitsu, honda, nissan, toyota) will not work on this car, I know because i bought them and tried.

TLDR, measure lash, remove cams, swap shims, install cams. If right, pass go and install timing belt, if not, start all over.

 

Correct, remove the cams completely to service the lifters without the Mazda special tools. Adjusting the shims is not a fun or quick job. You need to measure the lash, then measure the shim and do some math vs the factory specs and get size of the new shim. Then go to Mazda to order the shim closest to this size. One tip, use the shims you have to see if a shim you take out of cylinder 1, exhaust valve 1 can be used on cylinder 4, intake valve 2; in other words, check your existing shims and see if by moving them around you can get the lash back in spec without having to order 16 shims as they can be expensive.

 

There is a site that sells nissian shims in batches for way cheaper then buying from Mazda. You cans each around on here to get a link to it. I no longer have it saved and it makes me sad.

 

looks like I'll be pulling the cams then. thanks for replies.

 

fwiw, I do have the mazda SST, and if you have more than 2 or 3 shims to change (and not next to each other) its still easier and quicker to pull the cams...

 

That's very interestering to know. Whilst I never considered buying the SST (assumed they are expensive), I would have thuoght that the SST would be the best way.

Another question. My service manual is telling me .008 -.009 for the intake, and .012 -.013 for the exhaust. What do you set them for track? Aim for the loose end of the spec?

 

I managed to buy my SST second hand off a local forum user, for a fraction of the new price for one from Mazda.

I ran my track car (when it had standard cams) at .008 and 0.012 and just checked ( and then adjusted if needed) semi regularly so they remained at that.

 

Thanks for replies. Was all fairly straight forward with a little bit of trial and error to get clearances right. I'll recheck again after some high RPM running time.

The shims were harder to find that I thought they would be. Ended up with some toyota 27mm (I measured the miata ones at 26.92mm) shims intended for the 1UZ-FE. The slighlty larger shims seemed to fit ok with a bit of a push and click into place. It was interesting to note that the toyota shims have a little hole in them, anyone know why? They look like this (not my pic):

 

Good info.
I am doing this soon as well.
I think FM sells the mazda shims still.

 

Also, here is the link with the proper clearances and nissan part numbers:
https://www.miataturbo.net/engine-pe...arances-77716/

 

Err... anyone have this site handy?

I'm doing the BP5A swap shortly and want to do this instead of just swapping cams and hoping for the best...

 

There is a link in the thread I posted above.

 

Ah, it was cylinder head supply?

Thanks!