Iain's 20XE Trackday Nova

[turbojolt]

how do you clean up the head and bits so well?

[Iain]

Valves bench grinder with wire wheel. Head with tfr degreaser, nylon brush, a bit of careful scraping and wire pipe brush down the ports

[turbojolt]

cheers, i will be adding all them bits and bobs to my payday tool wish list

[MK999]

Yes pretty much what I expected and a thread on MIG confirmed. There's a clean silver line as if it's been sealing around each chamber but it's happened somehow.

Head was skimmed, block was checked and confirmed OK and he wasn't keen on decking it as he thought it'd had it before.

Unsure how it was done, I do suspect it's not perfect enough for MLS so popping a standard gasket on for the rebuild (choice between GM, Payen and Elring!)

I would get it skimmed again to make sure it's all good, you'd be surprised how much heads bow after being torqued and run. If you're running high comp I'd be tempted to find somewhere that can fly cut it and use MLS again. If it was fly cut it would have come back with a near mirror finish on it, and you would have noticed it being shiny shiny!

Also if combustion has been skipping across the block, check it very very carefully with a straight edge, clean it up as best you can with isopropyl alchohol and a cloth, NO abrasives. I suspect it will have low spots between the cylinders though.

and while it's all out double check valve seals, brake cleaner in the ports, dry the combustion chambers and look for leaks if you've not got a vacuum tester handy.

[Iain]

I really REALLY don't want to skim the head again. There's already no step on the edge and it's skimming into the casting marks. I remember it having curved machining marks in the head when it was done.

All stem seals have been changed. I'll spray some brake cleaner down there but it should be fine as I spent a while on the valves on the first build.

[Mark Sparks]

Sounds like you might need a new head if its been skimmed that much.
I can understand why you wouldn't want to want to skim it again but it needs to be right or your doing the whole job again in not so very long.

[Iain]

Yeah ideally I would need a new one, I might source one to slowly build up with nice parts.

I've had a straight edge on the head and I'm pretty sure it'll be fine to go back on as-is tbh, I didn't even notice anything that made me think it was blowing between cylinders until I stripped it so screw it

[Benn]

Not uprating the valve springs?

[Iain]

Talked to Kent on the phone who recommended the 1612 cams didn't need or want double springs. I could have got their uprated singles but it sounded quite pricey so hoping this was a freak accident

[Benn]

Ah ok. Crack on then.