John Cunningham
cunningham_john@bah.com
asks about hardened inserts for unleaded fuel. I do a course here at
Cornell in automotive engineering, and I discuss valve seat recession. I
have also done restorations for close to 50 years. I have installed
hardened seats in two engines recently.
The seats are cheap, and are routinely installed by machine shops that do
head restorations. They will not add much to the price of a valve job.
Our local shops are installing them daily in old tractor engines (we are a
rural community) to convert them to unleaded fuel.
The bad news is that hardened seats only slow down the recession. There
are various types of hardened valves that are suggested also, but these are
really expensive, and the additional improvement from the use of the valves
is not worth the cost. With stock valves and hardened seats, in an engine
with a relative low compression ratio (6.5 - 7.5), that is driven at
moderate speeds under 3000 miles per year you should not have any trouble.
It is valve temperature that is the problem. It is probably a good idea to
see to your valve guides, if you have any doubts about them. Tight guides
(but not too tight) promote low valve temperatures.
The various additives that are advertised do not do anything if they are
not lead, regardless of what they say. Only lead works. The hooker is
that it takes several thousand miles to work the lead out of an engine when
you switch over to unleaded, and in this initial period it is easy to try
something that does not work and conclude that it must be working. Lead
Tetraethyl is available in the US as Protek Lead from Vogel Products Inc.
860 Repp Dr., Columbus, Ind. 47201 Ph.: (812) 376-2775 at about USD17.00
the gallon. This is legal in all states here except California for use in
motor vehicles. You will have to inquire about the legality in Australia,
as well as availability. The US government evidently took the position
that the number of people willing to pay the extra to get the lead back in
would not be a problem. I put in about 8 oz with each tankfull. I do this
even with the inserts. Belt and suspenders.
John Lumley, Armstrong Siddeley 346 and Star, DB Lagonda.
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