I have finally got my old plymouth runnin and I have some concern about using unleaded gas in the old girl. Will it work ok or will I have to run a lead additive. I do have access to AVGAS but that won't help me when I go a any distance away from home. Oh, by the way the car is a 50 plymouth with the original flathead 6. Let me know because I am really anxious to get it out on the road.
I am running unleaded gas in my '66 Mustang with no problems. I am sure that there are varying opinions, but I don't know anyone using lead additive in old cars/engines...
What the problem is, the lead in the old fuel lubricated the valve seats. The new unleaded wont do that. If you haven't re-done the heads with hardened valve seats, I would probably recommend the lead additive. It won't hurt the valves right away...but in the long run, it could burn the valves & you'll have to do a valve job. At least that's what I've been told.
I know very few who have any verifiable problems with old low compression engines. I do run some Marvel Mystery Oil most of the time though.
the flathead six Mopar engines all (as far as I know) had hardened seats from the factory. No lead additive needed.
Mopar sled is correct and if you get a chance look at the p-15 d24 plymouth dodge site them guys help out a lot Thanks Bart (owned a 48 ply biz 218 flattie with no probs)
Ive heard that its b.s. to run lead additive and that it does nothing, but then Ive heard to run it because the seats need lubricated. I wish I knew what the truth was! I never run lead additive and have never had any problems, dont know if it will cause problems though
Exhaust valve seat recession and why> Think about the exhaust valve,it is constantly flowed over by flame and hot exhaust gases. The only time it cools is when it rests on its seat. The exhaust valve is made out of a much harder material than cast iron seats. Not all engines have replaceable seats. Some just cut the seat into the soft cast iron head or block. That flaming hot,harder than cast iron valve slamming against the seat without any form of lubrication will beat the seat to death. Tetraethyl lead was a octane enhancing chemical that also acted as a valve seat lubricant. Induction hardend valve seats are merely cast iron seats that have gone through a hardening process that is about .010 deep into the metal. Once you grind the seat to restore the proper angle you can bet the hardening is gone and the seat will fail much sooner than it originally did. Lubrication is a cushion to help make the soft cast iron seats live.
Once again, You don't really need lead additives to run in most car engines. I worked for Exxon Research & Eng. for 15 years, doing fuel research. Lead helps valve recession in stressed engines...towing, mountain climbing, lots of load most of the time engines. That does not usually describe our old cars. Lead is also used as a cheap octane booster, but most pre 55 engines can run on today's octane without boosters. Late 50's and 60's muscle cars CAN use the octane boost, though. It comes with a price. Lead can also form deposits on intake vavles and clog your airflow. I've seen it in high mileage engines, where you couldn't even see the shape of the valve any more, the deposits were so thick.
IAGREE WITH MARK I RUN MY Y-BLOCK ON UNLEADED GAS SINCE 89 NO PLOBLEM SOME OLD TIMERS WILL REMEBER THAT AMCO GAS WAS ALWAYS UNLEADED
Just a little lead additive can save and lengthen the valve life of your old engine, and that's the truth!
AMOCO gasoline never had lead, it was a selling point for them long before the lead/no lead BS. It was the "greenies" that brought all this eco=BS down on our heads costing us fortunes while they didn't bother to spread the word to the countries of the world still living in the Stone Age.
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