Cylinder decking, how much is too much?

[JZ05220r]

Hey guys. I have my cylinder being replated and freshened up at powerseal. The cylinder mating surface for the head gasket had lots of little dings in it. They told me they are going to deck the head. I just want to make sure this won’t affect the squish too much. I understand that there is no way of telling exactly how much material will need to be taken off. I told them that my RB head was set up for 93 octane pump gas. Do you think I should be ok and that these guys would consider these things when doing the work. Thanks

[SS109]

Lowering the cylinder height would in effect lower the head closer to the piston. This would increase compression and reduce the squish to possibly unsafe levels if the head isn't reworked to account for it.

[JZ05220r]

I guess what I’ll do is measure from bottom of cylinder to top on my current cylinder and compare it to the new cylinder. Thanks

[Chuck78]

You can custom cut your own base gasket out of a bulk sheet of uncut thicker gasket material, or have Cometic make you a custom thickness base gasket to correct your deck height, but this will also ever so slightly alter your port timing.
I'd ask if they can possibly make a custom MLS (Multi-Layer Steel) head gasket slightly thicker for you. Tooling up for MLS gaskets is more involved than paper gaskets or fiber type head gaskets though, so they may not do a 1-off. Since it's stock bore though and not a completely custom big bore size, maybe they can do this.
Also, with an MLS gasket, you could possibly stack a few layers from a second gasket over the dowels?

[Chuck78]

I wonder if they can Nikasil plate the head gasket surface after decking????
Perhaps it wouldn't do as good in the long term under compression though? Not a malleable finish? Doesn't hurt to ask.
Thicker head gasket is the best solution if possible. If not, a thicker base gasket is the easiest solution (but with altered port timing).

[JZ05220r]

I wonder if they can Nikasil plate the head gasket surface after decking????
Perhaps it wouldn't do as good in the long term under compression though? Not a malleable finish? Doesn't hurt to ask.
Thicker head gasket is the best solution if possible. If not, a thicker base gasket is the easiest solution (but with altered port timing).

Thanks I asked about that. Not sure what the deal will be until at least next week. I’d shoot for a thicker head gasket if it’s an issue.

[JZ05220r]

They are going weld and machine the cylinder head surface so I should be good to go.