re:
"I'm not convinced that the fuels that are available today, particularly in
CA I understand, are good enough to handle the amount of advance that the
original distributors can produce. "
91 octane ((R+M)/2) is the best you can get in CA (unless you sneak a little
avgas--
100 octane--in the tank ;). But 91 octane is 91 octane, in CA or any other
state (the
testing method is standardized), and I believe in the other CA (Canada) as
well.
I believe 91 octane ((R+M)/2) is equivalent to 95 octane using the "motor"
("M") method
(or is it the "R" method?) alone, which I believe is what is used in Australia
and GB
(but I'm not positive).
Question is, is 91 enough? I've run for 90K miles or so on mostly 91 octane CA
gas, with no problems that I know of, but my engine doesn't have particularly
high compression (don't think I got a great ring seal on the last rebuild).
bs
--
***************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
***************************************************************
-------------- Original message ----------------------
From: "Michael Salter" <msalter@precisionsportscar.com>
> Hi Ken,
>
> I would say, largely because of the way the pieces have broken off the top
> ring land, that there is little chance that that damage is attributable to
> anything but detonation. The other marks in the pistons are probably the
> result of the broken off pieces hammering around before they went out the
> exhaust port.
>
> There appears to be a cracked piece just hanging on in this picture.
>
>
>
>
>
> I have seen similar damage several times particularly on MGBs and would
> suggest that you check your distributor advance curve carefully both before
> and after you have the engine rebuilt.
>
> I'm not convinced that the fuels that are available today, particularly in
> CA I understand, are good enough to handle the amount of advance that the
> original distributors can produce.
>
> Detonation can be quite serious at highway speeds but completely inaudible
> to the driver. You can buy knock sensors which will turn on a light when
> detonation is occurring; might be a good investment.
>
>
>
> Michael Salter
>
> http://www.netbug.net/blogmichael/
|