[VAC] Re: Vintage haulers and unleaded fuel

[Dr. Gerald N. Johnson, electrical engineer]

Its going to depend on the engine. Truck engines in the 60s had hardened
valves and seats because they were expected to be worked harder than car
engines. Pickups may have had either car or truck engines depending on
size and source. Since prewar engines didn't have the benefit of lead, I
kind of suspect that valve designs from then weren't relaxed just
because of the lead additives.

Supposedly the lead deposits on the valves also help transfer heat from
them to the seats and so they can run a little cooler. At the same time
lead deposits in the ceramic severely shortens the life of spark plugs.

If an engine is old enough to need manual valve adjustments, you should
be able to detect a trend if the valves are wearing. If the engine has
hydraulic lifters, you might not notice the wear until the valve was
badly worn.

Gerald J.



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