Hi all. Just a quick question regarding carbon build up on pistons.

Does this just happen over time or is it caused by something not right with the fuel. Perhaps because the engine is running rich

and what's the best way to clean it off please (the head is off)?

Thanks.

Ziff

It happens with age.
Usual method is scrape it off carefully, don't use a screwdriver it'll dig in.
A 6" steel rule with rounded end works well.
Some people (like me) leave a ring around the edge, as it's folklore that removing it all will result in higher oil consumption if the motor has a fair few miles up.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc. I just noticed a bit of carbon on the tops of the pistons when I opened up the spare 998. As I'm planning to transfer the block to the vans engine, I thought I should attempt to clean it off before putting it all back together.
Ziff

Edit for spelling