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yeah i can see the hours in that!!

Yeah my rule is, cost and hours at a realistic estimate, then multiply that by 3

Those ribs took forever to straighten out but there is actually stuff all filler in them. I knew they would be the first point of contact for anything slid in or out of the back so any filler would just get chewed out.

What do you reckon happened here. These were checked before the Fast ignition box was installed and were fine. It was only two of the six spark plugs affected but I didn’t notice what cylinders they came from. One was probably from the same cylinder that the MLS gasket failed

Just realised I hadn’t mentioned the MLS gasket failure. This obviously happened before i took it to Whyalla hence why it was losing coolant. I took the head to the machine shop and got the gasket face cleaned up and they installed plugs in the coolant galleries. We decided to do this once we realised the MLS gasket had these blocked off anyway. It will give the chamber less of an excuse to relieve itself in the coolant holes. Amazing it ran so hard considering the leak.

Detonation, quite bad one too.

Detonation and very hot plugs 5s are so hot in an ngk I would probably run 7s if it has compression. we run 6s still but low compression and avgas. You are also running non resistor plugs you want bpr6efs or bpr7efs or TR6 it's a 6 heat range but non projected tip and acts a little cooler

Totally agree with Delco ...

Looks like 5 dark threads, that equates to about 2 heat ranges hot, that agrees with Delco, to 7's I would go ...

Can't stop detonation damage without stopping the detonation, however you can help the MLS hold up, ensure the surfaces are absolutely perfectly clean during assembly, any residual oil or other contaminate on the surfaces causes burn and failure.
That gasket shows signs of contaminates upon assembly.

I personally use Brake-Clean to clean the surfaces and a final wipe with Isopropyl Alcohol on a lint free.

Thanks for the replies. I hadnt considered the plug heat range, these are just the same type of plugs I have previously in these engines

Agree with everyone. Just a question. Was the detonation damage to the head gasket on the opposite side to the spark plug?