Hello,Anybody happen to know the exact year+month that Plymouth started rolling out Furys with hardened valve seats so that they could take unleaded gas?Had a search online and cant find anything more accurate than 'early 70s'.ThanksJon
It would depend on what part of the country you lived in to give an exact date. However most chrysler products were tolerant of unleaded gas by 1971 and all mopars had hardened valve seats by 1975. I recently had to have hardened seats installed in my 74 360 heads, as you know oil companies over the yrs. have continually removed additives from their fuels and hardened seats are a must with todays pump gas.
Thanks Dr Mopar, not sure where the car originated- its a 1971 fury so hopefully will tolerate unleaded ok. Might consider retro fitting hardened valve seats then,cheersJon
Jon, when I said the 71 would tolerate unleaded gas, I was talking about unleaded gas made in the 70's not todays unleaded fuel. If you don't replace the exhaust seats they will eventually develop hairline cracks.
Tetra-ethyl lead was used as an octane improver. It was the best one we had. It could raise the octane 6-8 points. The lead did not burn in the combustion process.It left the engine in particles. These coated the valves and seats, protecting them from corrosion. This was an after effect, not the reason the lead was put in.So much for science. If your not rebuilding your engine, do not do anything. The effect of valve seat burning is long term under hard use. Not running a high temp thermostat will help also, stay 160-180. If you don't have high compression, don't run 93-94 octane. Run 87 or 89. This will keep the combustion temps down. Most of us don't drive our classic enough to worry about the long term affect of unleaded gas.Don