Gerald,
Good explanation and description.
Most of the '50s and '60s cars still in use that I am familiar with have
hydraulic valve lifters which, as you stated, probably explains why we are
not aware of any unpleasant results from use of unleaded fuel. Most of the
old cars I am aware of are subjected only to very light and occasional
driving for car club activities.
Harvey
----- Original Message -----
From: Dr. Gerald N. Johnson, electrical engineer <[EMAIL PROTECTED]>
To: Multiple recipients of VACList <[EMAIL PROTECTED]>
Sent: Thursday, May 17, 2001 10:32 PM
Subject: [VAC] Re: Vintage haulers and unleaded fuel
> 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.
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