If I have an engine with heads that don't have hardened valve seats, can I just put lead additive in the gas and be fine?
Toilet seats aside, one of the side benefits of lead was that it helped prevent micro-welding between the valve and seat, principally on the exhaust side. This prevented valve recession. I have seen many times the effect of using unleaded gas with older, softer cylinder heads. Depending on vehicle, load conditions, and other factors, valve seat recession with unleaded gas and older (pre-1975) heads could range from neglible to severe (.125" recession in less than 5000 miles.Jmark said:Yes.
since there is a ten character minimum, I'll add this. What does lead have to do with anything. It was used as an anti-knock compound, not a seat protector.
Mark
X2 on the valve recession on extreme SEVERE duty stuff. My buddy had a fresh rebuild on a 68-70? 289/302? flat nose Ford van that was a single rear wheel mini-motorhome. After he got back fron a coast-to-coast trip, it was barely running. The valves were sunk that eighth inch or more! I think more! Never seen one that bad before, or since.machine shop tom said:Toilet seats aside, one of the side benefits of lead was that it helped prevent micro-welding between the valve and seat, principally on the exhaust side. This prevented valve recession. I have seen many times the effect of using unleaded gas with older, softer cylinder heads. Depending on vehicle, load conditions, and other factors, valve seat recession with unleaded gas and older (pre-1975) heads could range from neglible to severe (.125" recession in less than 5000 miles.
Yes, you can use a lead substitute as long as it's not in a truck hauling heavy loads.
tom