What is a cylinder head spacer?
 

This one:

2000 MAZDA MIATA 1.8L 1839cc L4 FI DOHC : Engine : Cylinder Head Spacer Shim Wiki Price $10.84
VICTOR REINZ Part # 5878S

Will this work as a (misguided) means of reducing compression ratio?
(Yes I've heard about the problems with reducing squish, I'm just wondering if this is the "spacer" people talk about)

http://www.rockauto.com/catalog/rafr...arcode=1363744

If I remember correctly they use these when replacing a head gasket after resurfacing the head to keep the compression ratio the same, It will lower compression, but not much its just like using a thick head gasket.

I think that is just a messed up name for a head gasket...

No head gasket in the world costs $10

Yes it is to maintain CR if the head is shaved. However, they can be run without a head gasket to increase CR or run with one to decrease. I forget how much it changed the compression on my 440. (It's common practice to run a shim alone with no HG).

Do us a favor and contact the vendor about application and CR changes. I would be concerned about running more material between the head and block with high boost. Seems like it could be a weak point.


^^^^Agreed, if it is $10 it is not the shim that I am thinking about.

Mopar steel shims for 440 $160
http://www.summitracing.com/parts/DCC-5155237

Except that calling it a spacer or shim is common. It's closeout priced, like yer Mom.

https://www.miataturbo.net/attachmen...1&d=1299713317

I see there is a 5878 and a 5878S...

Part Type: Cylinder Head Spacer Shim



* Manufacturer: VICTOR REINZ
* Part No: 5878S
* Notes: Requires Sealing Compound

Closeout Price: $10.84
Only 1 Remaining!

It's a Nitroseal gasket made by Clevite/Mahle I believe.

good thread: http://forum.miata.net/vb/archive/in.../t-328263.html