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Re: Cylinder head experiment.

From: Hank Dozier
Date: March 11, 2002
Time: 17:20:45


The lead in fuel acts as a dry lubricant on both the valve guides and valve seats. It is possible to run without lead, but some sort of seat conditioner such as the product Lubrizol makes for additive to M-100 in the diesels (a lubricity modidifer) MUST be substituted, or else the seats will erode due to the lack of hardness. The actual erosion if looked microscopically is a scuff erosion due to lack of surface hardness and heat. Interestingly enough, aluminum head race engines can run with manganese BRONZE valve seats and live, but this is due to the fact they also have a softer valve compound (Titanium), and the fact the aluminum and the bronze pull the heat away extremely well. Intake valve, being cooled by the fuel and not exposed to the exhaust gas flow do not need seats unless one uses extremely aggressive cam profiles.


Last changed: July 19, 2018