> Date: Tue, 22 Jun 93 15:42:15 EDT
> From: jesup@cbmvax.cbm.commodore.com (Randell Jesup)
> Subject: Re: Octane, lead
>
>>> o 88 octane leaded, or 92 unleaded -- which to use?
>
> You can actually buy leaded? Lucky dog! I haven't seen leaded
>around here in 3-4 years or so.
>
>>Common net.wisdom says the 92 unleaded is better, at least for the higher
>>compression engines. I use unleaded 92 in my GT6+ and TR250. According to
>>several folks on the net, valve damage from unleaded fuel isn't a problem.
>
> You might want to do a 50/50 mixture of 88 leaded and 92 unleaded
>once in a while. The octane should still be plenty to avoid pinging unless
>you've upped the compression, and some lead can't hurt. (Lead has a non-
>linear affect on octane, so the result may still be ~92.)
>
> If you drive >10K miles/year, you might end up having to deal with
>head repairs on unleaded in some cars. It depends a lot on the car. Even
>fairly small amounts of lead can help avoid recession, according to the
>UK car magazines.
> Randell Jesup, '70 TR6
The Vintage Triumph Register asked its membership if anyone had experienced
head/valve problems due to the unavailability of leaded fuels. We only
received 5 responses from our 3500 members. None of the five indicated any
valve recession problems, dispite long term use of unleaded fuel only.
One TR-3 owner had run his car exclusively on Amoco unleaded since he
owned the car with no problems. I suspect the TR cylinder heads are
far less prone to any valve recession problems due to unleaded
fuel than the pre 1960 domestic (USA) classic cars.
What some folks do, just to err on the side of prevention, is to
periodically add a few gallons of racing fuel (eg. CAM2, etc). You
may not be able to do that directly at a pump, but you shouldn't
have any trouble finding it and filling a 5 gallon gasolene container
with the stuff and then putting in your tank later. The racing
fuels have 3 to 4 grams per gallon of lead as opposed to only about
0.1 gram/gallon of lead found at regular leaded fuel pumps. Heck,
here in the east you can't even find leaded regular at all, but there's
a local Sunoco station that has a CAM2 racing fuel pump ($3/gallon).
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