new shortblock deck surface Ra? (1 Viewer)

[SuperJ]

Howdy,

Lining up my ducks for a replacement FZ built on a new shortblock and head. Would like to use Cometic gasket. Have others noticed the Cometic minimum 50 Ra on the gasket surface of either or both the block and head?

I would hate to have to machine a brand new part.

Thanks in advance.

 

[audi2nr]

i did notice that and i had my brand new toyota head shaved the minimum to meet the requirements for an mls headgasket. my block was the orignal so it needed a haircut anyway. maybe reach out and see if your machine shop has a surface roughness gauge? imo if there's no boost involved slap it and go, if there is boost involved shave it or minimum get the surfaces measured.

 

[Somebodyelse5]

50 Ra is pretty rough, i would be real surprised... but any self respecting machine shop should have finish gauges. a real good one will have a profilometer.

 

[White Stripe]

MLS head gaskets from what I understand can handle no rougher than 60ra in general. LS motors use MLS head gaskets, so a machine shop that does a lot of LS stuff should get you a good surface.

 

[cruiserdan]

With a new block and a new head I wouldn't use anything but a new OEM head gasket.

If you have your heart set on an MLS gasket you should rebuild a seasoned block and head around it.