No - the valve timing is perfect and the belt is tight. I checked it.
I have a theory that the clearance was never right and it may explain why the engine never idled properly and spits flames out the back on over run.
My engine builder did the head and I didn't check the clearances when putting it onto the block. A lesson has been learnt!
If I set the clearances correctly and the engine idles well, it will prove my theory. I have been blaming the injectors for the bad idle. The previous engine idled fine with those injectors.

track_mr2
Did you check your cam timing at all? I don't think its likely that all four cylinders valves relaxed at exactly the same time and exactly the same amount to cause this issue. Even on race engines I've had from new I have never come across valve seats relaxing to cause loss of compression like that. Even high revving factory engines like motor bike engines don't have this issue. I'd check your cam timing, if your running adjustable sprockets maybe they have slipped if they are not the doweled types.

The timing is fine. I'm running standard sprockets. There is no clearance at all between the base of the cam lobe and the shim. Even if the timing was wrong, there should be some clearance. All 8 of the inlet lobes have 0 clearance.

B24
Are you running shim under bucket?

No - standard buckets and shims

I'll be taking all the shims out tomorrow, measuring them and ordering some thinner ones. I won't know the exact thickness I will need though I'll probably buy one set one size thinner and also another set two sizes thinner just in case.
Because race car! It never ends.....

B24
I also agree with track mr2. Could well be a cam gear that moved. Certainly makes perfect sense. Hey track mr2, feel like helping me assemble a 2GR!
 

Hahaha I would but I'm in Melbourne.
 
Admin I still reckon something else is wrong BECAUSE you were able to start you car and run it fine for 3 session etc...So something has changed for your car not to start or run even worse now right?
 

Clearly if they do not have any clearance at all they will not be seating correctly. Valve seats will be copping it too.
 
I wondered why your idle was so crap.

I think you should get the clearances correct then see what happens. You should be able to remove the shims then use a feeler gauge to check the clearance. If you set these out 'in order' you will have a clearer picture how far they are out. Also check if he 'tipped' the valves. If the valves are not tipped and the clearances from the bucket to the cam lobe are all over the place, this could effect your 'cc' in each of the combustion chambers. Its a minor detail, but still a detail when chasing performance.
Have you had the injectors cleaned and tested? Should have it done while you are fine tuning that engine for MTC 2015!
 

Tipping valves? is that some crazy name for lapping the valves?

track_mr2
Admin I still reckon something else is wrong BECAUSE you were able to start you car and run it fine for 3 session etc...So something has changed for your car not to start or run even worse now right?
 

Something did change - I ran it hard for many laps at Eastern Creek. If you want to properly test your race engine, that is the best track to do it on! I killed my last engine there.
Seriously though I think the valves were closing just enough for it to start and run and as the engine has been used, it has settled and now the valves leak too much for it to start. We are probably only talking about a couple of thousands of an inch. Maybe the seats have receded slightly?

I get what you mean but based on what you are saying, all 8 intake valve seats have receded by exactly the same amount at exactly the same time on a engine your reving to 7000 maybe 8000 rpm, it just doesn't seem likely. Furthermore your exhaust valves are all perfect. So your engine builder set the exhaust valves right and intake valves wrong? I'd be looking to some common link to all the intake valves like the camshaft, sprocket, timing belt etc... to make sure everything is right. You had three sessions fine on the day then the fourth it went and you ending up with 75psi compression on all cylinders. You should have noticed a big, big power drop if it went while driving.