trickydicky43richard Posted April 10, 2016 Share Posted April 10, 2016 Hello, I was wondering if the late original 30's early 40's flat Chrysler sixes had valve seats adequate for unleaded or would they require a lead substitute fuel additive,? Thanks, R Link to comment Share on other sites More sharing options...
keiser31 Posted April 10, 2016 Share Posted April 10, 2016 They were originally built for unleaded, so it should be fine to run the new fuel. Link to comment Share on other sites More sharing options...
ply33 Posted April 10, 2016 Share Posted April 10, 2016 Came from the factory with hardened exhaust valve seats starting in, I believe, 1933. No issues with lead free gas at all. Not sure what additive packages they are using in Australia but in the U.S. modern gas additives are not kind to original style rubber components in the fuel system, so if your fuel pump and flex line haven't been replaced in the last 10 or 20 years you might have a problem with those. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted April 10, 2016 Share Posted April 10, 2016 They have exhaust valve inserts installed at the factory. Were made to run on low lead or unleaded gas of 65 octane. If you are concerned about upper cylinder and valve wear you could add a little upper cylinder lubricant to the gasoline. Redex, Marvel Mystery Oil, Bardahl or your favorite brand. This is more to protect cylinders, rings and valve guides than to prevent valve burning. These additives claim to reduce wear and lengthen engine life. Today's gas is very dry and often includes alcohol and additives that make it dryer. Link to comment Share on other sites More sharing options...
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