Valve clearances on a 99 head- Please check my math - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-18-2009, 12:12 AM   #21
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Several things...

1) Nicks head came to him from the engine builder this way... the valves were improperly machined. The right thing to do is take the head off, take it back to the builder and say "fix this".

2) You can't accurately grind the shims without a surface grinder, and they need to be flat. You simply can't keep them flat enough hand grinding.

3) I'd be suprised if there's enough variance in the lifters to be helpful, but it would be interesting to see Joes measurements... I have a set of 99 lifters out of a head at the moment I'll measure when I get a chance as well.

I have ground shim unders by hand, although they are much smaller in diameter. I was able to maintain the proper thickness through out the shim. I did mess a few up before refining the technique. I am sure it would be more challenging (and maybe not possible) with the large shims. I would like to try it though.
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Old 12-18-2009, 04:19 AM   #22
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1) Nicks head came to him from the engine builder this way... the valves were improperly machined. The right thing to do is take the head off, take it back to the builder and say "fix this".
This is one of the main issues, head was installed on the motor with two clearances in need to being set properly. Something i am yet to do. The main issue i have is that the builder of the head is 3-4 hours north of where i live. Big PITA for me.

If this is something i could do on a weekend i would much rather go that route. Ill get in contact with the shop that did the head work. Which i already have some tension with since they decked my head without asking me.. Bill i am going to shoot you a PM.
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Old 12-18-2009, 11:37 AM   #23
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I'm in the process of doing the same thing, only with Supertech valves that are .6mm longer than factory. Talk about having to R&R the valves and keepers a TON of times.

Has anyone found a reasonable place to purchase the shims, preferably in a kit? VW used to sell kits containing every possible thickness shim. I'm hoping Mazda does the same.
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Old 12-18-2009, 12:22 PM   #24
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Did the builder install the head on the block for you? If not one should check the clearances before installing the head.

What I think happened is that the builder did the clearancing by grinding the tips of the valves. This is common. I think what then happened is he f-ed up and ground too much off of the valves that have too much clearance.
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Old 12-18-2009, 12:24 PM   #25
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I'm in the process of doing the same thing, only with Supertech valves that are .6mm longer than factory. Talk about having to R&R the valves and keepers a TON of times.

Has anyone found a reasonable place to purchase the shims, preferably in a kit? VW used to sell kits containing every possible thickness shim. I'm hoping Mazda does the same.

The shims are not cheap, there is a kit that has an assortment of shims, at least for the shim under buckets, but that assortment will cost over $800.00.

What really sucks about shim overs, is the fact that you have to have a shim in order to take a measurement. If you have a longer valvestem, you will have to ballpark it with a thin shim, take measurements, do the math, and then order the right shims. Plus the fact that it is likely you will make a mistake or two during the process, you end up buying a lot of shims.

With the shim unders, you can put a lifter bucket without a shim to get a measurement. That way, you end up with fewer shims. I also think that the under bucket style shims are much less expensive. You also have the added benefit of a lighter valvetrain. It is not a bad investment.
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Old 12-19-2009, 03:57 PM   #26
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Originally Posted by JasonC SBB View Post
Did the builder install the head on the block for you? If not one should check the clearances before installing the head.

What I think happened is that the builder did the clearancing by grinding the tips of the valves. This is common. I think what then happened is he f-ed up and ground too much off of the valves that have too much clearance.
Yes, what happened was the guy who i had build my motor builds spec miata bottom ends. He did it on the side for a very sweet deal. The head needed to be worked over due to some rust issues on the valves and cams.

He took the head to a local mechanist near his place (4 hours north of where i live) had them install everything on the head and my builder put the head on.

I can only assume the head was assembled improperly. :(
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