I KEEP BURNING PISTONS WITH MY MODIFIED ENGINE

  • Tiny
  • leslien
  • 1980 Mini Cooper S
  • 7,000 miles

I have a classic Mini and has a 1275 engine modified to 1380 cc using 73.5 pistons. Compression ratio is around 13 : 1 I had gasket problems and now it has started to blow pistons. Earlier one piston was burnt and a friend told me it was running too advance and it was the reason to burn the piston. Then I replaced the piston and Retard the engine to have maximum advance of 35 at maximum RPM of 7500. Again another piston was burnt. I am using 100 octane petrol. What would be the reason to burn the piston. Also the car was not moving fast. I am using NGK Cooler (10) plugs. I have another similar car and it has no problems. The car does not heat up and the temperature is normal.

Wednesday, April 11th, 2012 AT 3:18 AM

2 Answers

  • Tiny
  • merlin2021
  • Expert
  • 17,583 posts

Could be running too lean, too much oxy in the mixture can destroy metal.

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Wednesday, April 11th, 2012 AT 8:35 AM
  • Tiny
  • leslien
  • Member

I had changed jets and was running rich, the plugs were dark and was not running lean.

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Thursday, April 12th, 2012 AT 2:30 AM

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