Iain's 20XE Trackday Nova

[scott.parker]

Not good dude, hope there's no other unseen damage, sometimes bend valves an jam the guides in?

[Benn]

Oh bugger, uprated ones the way forward.

[Iain]

buy double valve springs the bigger cams are probably botteming out the spring

You reckon? If the springs were bottoming out I'd expect loud clattering or some sort of mechanical locking as the camshaft wouldn't be able to turn properly?

sorry to see this mate, could be worse I'm sure this isn't going to tax your skills

you think its pure coincidence this happening after the lumpy cam going in?

Everything has gone wrong since trying to mod it tbh This week I've had to replace the ICV to resolve the dodgy idle and fit a new coil to fix some hefty misfires. I don't know if the cams have caused this tbh

Oh bugger, uprated ones the way forward.

Undecided whether to fit just one new one, a full new set of standard ones or upgrade them while I've got the chance. Upgrade is probably overkill as I won't be revving beyond 7500 or going much more wild on the cams.

[turbojolt]

ive got a gm head sat in my shed that you can BORROW while the work is happening to your current one, if it needs to get on the road quickly

(mind you it is untested so dont know how helpfull this offer really is )

[Iain]

NP there's no rush to get it fixed, there's no trackdays booked at the mo!

[MK999]

You reckon? If the springs were bottoming out I'd expect loud clattering or some sort of mechanical locking as the camshaft wouldn't be able to turn properly?

Everything has gone wrong since trying to mod it tbh This week I've had to replace the ICV to resolve the dodgy idle and fit a new coil to fix some hefty misfires. I don't know if the cams have caused this tbh

Undecided whether to fit just one new one, a full new set of standard ones or upgrade them while I've got the chance. Upgrade is probably overkill as I won't be revving beyond 7500 or going much more wild on the cams.

If the springs aren't man enough it'll valve bounce, sometimes very audible but if it's only very slight it might just feel like the limiter is coming in. But this will happen dynamically, cams will 'fire' the valve away from theirselves at high speed, you won't necessarily notice it just turning the engine over.

Just one of the bizarre things with cars, upgrade something and it starts failing left right and centre!

Personally I'd avoid standard replacements on a car the age of a Nova, you've no idea if they've been sat on a shelf for 20 years and in what conditions. If they are new 'standard' replacements the quality is probably questionable as third party parts are getting worse and worse recently. I'd talk to whoever your cams are done by and ask what they recommend, going too stiff will actually lose you power as the engine is turning over rock hard springs.

[Iain]

On with fixing my valve spring problem. Head off.



It all looks carbony but the bores look good, no scoring or damage



Head off with problem valve:



Rest of head looks pretty good, some weird build up on a few of the exhaust valves though?



And the cause of it all! Valve is good, spring is in three pieces




I'd like some advice on the head gasket please... You can see some darker marks between the cylinders on the head, and also on the block. Check the pics above for what I mean. Does this imply there's been some sealing problems around the bores?

I'm using a Cometic 1.9mm MLS headgasket, if the marks are possibly sealing issues I may look to using a standard gasket but I'm a little unsure.

[Iain]

Well I think I've decided to go back to a standard headgasket due to the marks on the head and block, it'll have a slightly higher compression but will hopefully seal better.

On with the head build...

Wonder why it was burning lots of oil



Stripped and cleaned:



Cleaned all the deposits off the valves:



Cleaned (ish ) the head and relapped the valve seats:



1x new early valve spring!



All done!

[MK999]

Looks like your gasket has been blowing across. Was the block decked and head skimmed when you rebuilt it? And was it ground or fly cut ('diamond' finish like a scene whores wheels ). MLS will be very sensitive to surface finish.

[Iain]

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!)