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Discussion Starter #1
I have the head off my Weber carbed Spyder; there is a good amount of carbon built up on the surface. Any thoughts on cleaning off the piston surface? I have been using a plastic scraper but there are a few areas that need some persuasion.
Has anyone had any experience with a liquid? Certainly dabbing it on the area as opposed to pouring it on.
Thanks in advance.
 

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The most important thing about cleaning pistons while still in the engine is NOT to disturb the carbon build up above the rings. If you do that you will likely end up with a smoker.

I just use a metal scraper ... when the piston is at top dead centre.
Pete
 

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Don't scrape the carbon off...you will NEVER get all of it from between the rings and top of piston skirt and it may damage the bores.
I know it's nice to think you're doing good by cleaning the tops of the pistons, but please, just leave them alone. If you absolutely must get all that carbon off (and you've started now...) use lacquer thinners and a stiff bristle plastic or brass brush. Oil the bores and change the oil after you do this though.
As an aside, carbon is an excellent insulator, so it doesn't hurt for it to be there as long as it's a thin, smooth coating. If it's a thick, irregularly shaped coating you would be smart to find out why and rectify that issue.

Regards, Andrew.
 

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or just reasemble it as is. then fire up the engine and get a small spray bottle with water and gently spray it in the intakes while the car is unning and in a little while you will have very shiny pistons:D seriously, have you ever taken off the head of a car with a trashed head gasket? those pistons are as shiny as they can get.
 

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Discussion Starter #5
Thanks all. Great information.
 
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