After I broke a couple of cooling fins off my TQ Black's 3 port head I bought a new head off a 4 port Hyper 21. I took the broken head off and checked that the new one was the same but it s not , the bit that the glow plug sits in (sorry I dont know what its called) sits in the bore about 1mm deeper will this be ok or will it screw the compression up?

Cheers

Cant you use the head button (part the plug goes in) from the old engine with the new heat sink (top part)?

If the engine turns over without the piston hitting the head, the new button should be fine. You'll just have to see how it runs with the new compression ratio.

You can also double up on the head gasket / shim to lower the compression a bit.

Its not as simple as lowering or raising compression, shims adjust compression and timing, which need to be changed in relation to fuel percentage.

The old button head and new cooling head should work together, but if not just buy a new correct head.