[Copperbottom]

I'll try to cut a long story short: On wednesday 14th April I had my brand new engine run in and set up on a rolling road (I won't mention any names),it had about an hours' running at different revs before the 1st power run showed it to be running way too weak so larger main jets were fitted into the carbs,still too weak so larger still jets (180s) were fitted and the power came up along with the co level at high revs,the operator then fitted some 200 air correctors, ran it up to 7000rpm and said that'll do. He then tweaked the ignition timing and did a couple more power runs to find the best setting.
On Saturday I went out for qualifying,completed 3 slow laps to let everything warm up then as I came out of clearways went for a quick lap changed from 3rd to 4th at 7000rpm only to find that the car slowed down! I checked the temps and oil pressure but they were fine so pulled into the pits to have a check under the bonnet only to find a heavily breathing engine so I limped back to the paddock,left it to cool down and removed the head to find that no1 and no4 pistons had holes in them from detonation!!

Who is responsible? The engine wasn't touched between the car being loaded onto the trailer and taking the head off after qualfying.
The carbs,pump,distributor etc were used on my old engine which I actually refitted saturday night so that I could race on sunday and it ran like a dream after I swapped back to the old mains/airs.

One thing that I have found is that the air correctors that were fitted to my new engine are all different sizes! 1 is 2mm (200) 1 is slightly larger and the other two much bigger.

Engine is an 1800cc (85.9mm bore) ford crossflow with twin 45 Weber carbs on 38mm chokes.

It looks like I'm going to have to buy 12 pistons just to get the 2 that I need as they are no longer made and the maker will only produce them in batches of 12!

Your views please Gents.