Lead Free Gas

[Bill Mulholland]

Hi JD; The hardened parts are the valve "faces" and "seats". In using unleaded gas which has the "tetra-ethyl lead" among other additives removed, this also removed the lubricating effect of leaded gas. The valves actually rotate as they come down on to the seat, This served to remove carbon deposits and allow even cooling of the valves. If you look on the manifold side of your engine on the side of the block, you may find a small tag rivetted in that loc. It is titled "RCEME Rebuilt Engine" and will show the bearing size, cyl bore, etc. I doubt very much if your truck has survived with the original motor, as these Dodge engines had a very finite life span, mostly due to driver error in over revving or in the case of Sigs Vans, excessive idling to keep the batteries charged, which in turn caused premature engine failure. Most of the later rebuilds had hardened valves and seats installed, so running it with un-leaded gas will not cause too big a problem. But to do a real kindness to your poor old flat head(engine that is) pick up a container of LEAD-SUBSTITUTE(various brands) from your local auto supply. All my old engines get a dose each time I have enough money to put a tank of gas aboard, and I have never had a problem with valves in over 20 years of restoring.
Cheers, Bill