M20 piston slap

["Apfelthaler, Horst" <Horst.Apfelthaler@xxxxxxxxxx>]

Hello,

I have a very bad (kind of knocking) noise on my project car's m20/b27
engine.
It seems that its piston slap because in the meantime I swapped a lot of
components
like head, oil pump, water pump, conrod bearings... for different reasons.

The noise is still there after a cold start. 
You cannot hear it at idle, but when you accelerate it sounds like a diesel.
There is no noise when driving for >5min, or when the engine has reached its
operating temperature.
I currently run Castrol TXT 5W40 oil.

Questions:
Is there a cheap method to minimize the slap - or is it time to build a new
engine?
Is piston slap harmful to the engine (life) or is it just an annoying noise?


Thanks for help


Horst
http://silverstone.fortunecity.com/chicane/541/

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