At 11:10 PM 7/18/97 -0500, dmeadow@juno.com wrote:
>
>
>
>That's the first time I ever heard of that, and I wonder if anyone you
>talked to actually experienced this. Maybe it is an urban legend or they
>weren't installed correctly to begin with.
>
>>This whole history should generate some discussion of whether or not
>>it
>>pays to modify the valves etc. for un leaded gas use, as the cure may
>>be
>>more dangerous then the disease. Maybe this applies only to T types as
>>the
>>later cars, especially the later B's were built for unleaded and the
>>casting procedures for the head may have been modified to accept the
>>unleaded valve train.
>>
>>I would be interested to hear comments.
>>
>By coincidence, this topic was also covered by Mike Ash, Technical Editor
>of MGA! in a tech session today. He says he has a couple of cars that
>have done 50k to 60k miles on unleaded gas without hardened valve seats
>and hasn't had any noticable difficulties. He hasn't had those heads
>off, though, to see if there is any valve recession. He does recommend
>the stellite valves, whether or not you get the hardened seats and bronze
>guides. Other sources I have heard seem to support Mike's experience. I
>would be curious to hear if anyone has actually seen a head whose valves
>had receded due to use of unleaded gasoline-- I have yet to hear of
>anyone with first hand experience with this supposed phenomenon.
>
>I purchase some of the British enthusiast publications, which seem to
>reflect some amount of hysteria over this subject, since they are now
>phasing out leaded gas in that country. I think there is more concern
>than is warranted, considering the evidence so far.
>
>In any case, I have never heard anyone knowledgeable on this subject
>recommend pulling a good head just to put in hardened seats, etc. They
>only recommend it be done if you have to do work on the head anyway.
>
>David Littlefield
>Houston, TX
>
Thanks David. I have renamed the topic to unleaded heads, and hope this
brings more comments like Mike Ash's
Mike
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