I went to a track day Satruday to run in my rebuilt A15. Half way round lap three the motor lost power and dropped a cylinder.

The rear most freeze plug had somehow popped out; I can't remember if I had them replaced when I had the block machined. To be honest of the four motors I've built over the last 20 years I can't remember replacing any of the freeze plugs. I'll have to dig out the receipt and see if I actually had them replaced.

I pulled it apart this morning and three of the combustion chambers have damage. The bore on the number three cylinder appears to have some scoring.

I'm not that upset about this particular GX head as it's the one that's had 2mm milled off the thing.

Luckily I have a fairly fresh A12 short block that I had been using; now I just need to either repair my unmilled GX head (it's got a single hole as opposed to three) or find a replacement head.

Did it burn the valves? If so maybe just throw new rings in the block along with the repaired head. A little scoring works on a street engine, dunno about racing

Dave sadly you can feel the scoring on the #3 cylinder. I could slap rings it and it would likely run but that's not exactly the best approach.