I am no expert, just have to much time on my hands to think about it whilst working, anyone want to let me know if im on the right track with my thinking.

If the clearances are spot on a higher spring pressure shouldn't be an issue as it should follow the cam lobe smoothly. If the clearances are wrong or the cam lobe is faulty then a change in clearance could cause the spring to snap back into the seat instead of smoothly following the lobe. If you use too low a spring rate then the valve could float on the lobe at some point creating to much clearance for a moment which results in the valve snapping back into the seat. Snapping back into the seat too many times could cause the valve to fail like it has.

Or the valve seat isn't cut squarely into the head so it was putting pressure on one side slightly. Looks a clean break like too much valve spring pressure and it pulled the head of the valve off. (not saying it has or this is even possible) acurate measurements of the damage may help determine the cause.

Valve clearances weren't just in tolerance they were all exactly to manufacturer specs accurate to 0.001"

Seats werent re cut or replaced they were just OEM subaru ones. They were however reground by hand to seat the valves properly.

With regard to cams. Valves don't just snap shut, they physically can't. The cam will slow the closing speed of the valve just before it gets to the seat.

Supertech have confirmed by email that a higher spring rate would not lead to failure as I asked that question.

But they've also said that one of their valves wouldn't just fail like that. Although plenty of failures on Nasioc tell a different story.


To answer a few questions I seem to be getting:

Yes I am going to rebuild it.

No it wont be run with lesser power, if anything I'm going to throw more boost through it.

And yes it will be hammered down the drag strip again when it's built.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

Good man!

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Huge range of extinguisher brackets for cars!

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Where's your build thread gone?

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Fuck your signature

Deleted. Best ask Daz why.

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Doing it for all the wagons out there

Really. ASG related?

That was one of the most interesting and informative builds that I have seen for a long time.

Agreed ... One of the better information build threads.

Reasons?

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[COLOR=Black]Liberty GT Spec B tuned 240 HP & 372 Nm at the hubs.[/COLOR] "Instead of banning high performance cars - ban low performance drivers"

I asked for it to be removed and had my reasons for doing so. Nothing ASG related that chapter is pretty much closed as far as I'm concerned now.

It was time to move on from all the negative shit that was on there.

Providing this thread doesn't go the same way I might document the new build which will be equally as detailed.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds

Less posting, more spending tonnes of money and building


Sent from my Ultraphone 5000 using Tapatalk

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No more GC8, sad face.
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