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1979 620, l20b with flat top pistons


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Im new to forums in general, not just this one. So I apologize if this is a question over done or if I’m posting in the wrong area. I’m currently rebuilding an l20b out of my 1979 Datsun 620. I have 86.5 mm flat top pistons that were made for the l20b so no modification, and a mild isky cam. My question is given that I am going to run on 93 octane. Is there anything else I need to do to ensure this build goes well with flat top pistons? Thank you for any responses! 

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Well you'll have plenty of compression (just over 10) so lightly round off any edges in the combustion chamber. Doesn't have to be much, just sandpaper them. You could polish the combustion chamber after with compounds and soft wheel. Try for mirror finish. This will reduce deposits sticking and the likelihood of a hot spot causing pre ignition. You might find a colder range plug will help with reducing ping. Higher compression will burn faster so the timing may need to be backed off as well. Generally higher compression (without pre ignition) is a more efficient way to capture energy and turn it into motion. The increase in mileage can off set the added cost of a higher octane fuel.

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