Scooterotica

Sounds like an eighties cop show doesn't it? Well it isn't.

Rebuilding my top end after a Chris sturgess tune and want to make sure the squish is as accurate as possible. So I'm dry building then when I'm happy I'll do a final build with Threebond on all the gasket faces. I have a base packer and thick head gasket (1.2mm) so I need 4 films of Threebond.

My question is, how much should I allow for all 4 layers?

I know I can recheck after the build through the plug hole, but I don't really trust that method.

Anyone know?

loctite on head IMO

i agree with eibar loctite on the head gasket, not too much, you dont want it down the bore, i turn my engine so the barrel is pointing downwards when a torque the head so any locktite runs into the head, the 3 bond squashes up to the thickness of a cigarette paper so it will add next to nothing to your packer thickness, same with the locktite

Which Loctite are we talking about here?

sorry should have been more accurate, a high strength stud lock, other makes similar to locktite do a good job, a lot of people prefer not to use a head gasket at all, and set up the squish my machining the head so no gasket is needed, just a bit of studlock to seal the surfaces.

Three bond to base packer, Loctite 510 to head (only a smidgeon required, squeezes out to minimal thickness). The RT head is lipped so no issue with squeezing out into chamber...

To the OP, I very much doubt your going to make any appreciable difference to the thickness of the gasket faces using the sealant but you could factor in an additional 0.2mm just to be on the safe side.
As for sealing the head without a gasket, I first lap the two surfaces together then use Stag Wellseal.

I use threebond myself on all faces/packers and onece torqued down the difference to your squish by using this will be next to nothing.

in case anyone wants to know...........

I measured the difference in thickness between a pair of head gaskets torqued together on their own and then with a layer of threebond between them and couldn't measure it with my verniers (couldn't be arsed to get my micrometer out).

Bazza3004 is correct; I couldn't measure the difference, so therefore less than 50 microns (that's the resolution of my verniers)