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If you change to a lower octane then it is more likely to ping/pink, and =
this is more likely to happen in a high compression engine than a low. =
If you must use that fuel - is it cheaper? - just back the timing off =
until you can't hear pinking at any combination of throttle opening, =
revs and load.
The factory specs on original fuel were conservative to take account of =
engine component tolerances and many engines can run more advance =
without problems and give better acceleration and cruising economy - BT, =
DT back in the day. Haynes agrees and says to run at full throttle =
between 30 and 50 in top gear and set the timing so that faint pinking =
can just be heard. For me that's too aggressive, like you I've had =
part-throttle pinking on hills that goes at full throttle, hence my =
modified recommendation. I also found that the change to unleaded =
increased the tendency to pink, so on this engine that never could run =
more advance than book on leaded has to be slightly retarded from book =
on unleaded. E5 hasn't made any difference, E10 will be arriving here =
this year but only in the lower of the two octanes usually available, so =
I will continue to use the higher in the roadster, and change to that in =
the 'low compression' V8.=20
PaulH.
----- Original Message -----=20
It appears to run well enough, but I have had a couple of issues come =
up where there was a low-speed but high load situation, like going up a =
short hill with a 15 mph speed limit. I could hear it pinging some.=20
...
I expected the timing to be too far advanced at that RPM, but if =
anything, it was slightly retarded.
'''
Does anyone else run 87 in a high compression engine, or have I gone =
off on a fool's errand here?
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<DIV>If you change to a lower octane then it is more likely to =
ping/pink, and=20
this is more likely to happen in a high compression engine than a =
low. If=20
you must use that fuel - is it cheaper? - just back the timing off =
until=20
you can't hear pinking at any combination of throttle opening, revs =
and=20
load.</DIV>
<DIV> </DIV>
<DIV>The factory specs on original fuel were conservative to take =
account of=20
engine component tolerances and many engines can run more advance =
without=20
problems and give better acceleration and cruising economy - BT, DT back =
in the=20
day. Haynes agrees and says to run at full throttle between 30 and =
50 in=20
top gear and set the timing so that faint pinking can just be =
heard. For=20
me that's too aggressive, like you I've had part-throttle pinking on =
hills that=20
goes at full throttle, hence my modified recommendation. I also =
found that=20
the change to unleaded increased the tendency to pink, so on this engine =
that=20
never could run more advance than book on leaded has to be slightly =
retarded=20
from book on unleaded. E5 hasn't made any difference, E10 will be =
arriving=20
here this year but only in the lower of the two octanes usually =
available, so I=20
will continue to use the higher in the roadster, and change to that =
in the=20
'low compression' V8. </DIV>
<DIV> </DIV>
<DIV>PaulH.</DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV><BR></DIV>
<DIV=20
style=3D"FONT-FAMILY: arial, helvetica, sans-serif; COLOR: #000000; =
FONT-SIZE: 12pt">
<DIV><BR data-mce-bogus=3D"1"></DIV>
<DIV>It appears to run well enough, but I have had a couple of issues =
come up=20
where there was a low-speed but high load situation, like going up a =
short=20
hill with a 15 mph speed limit. I could hear it pinging some. <BR=20
data-mce-bogus=3D"1">...</DIV>
<DIV>I expected the timing to be too far advanced at that RPM, but if=20
anything, it was slightly retarded.</DIV>
<DIV>'''<BR data-mce-bogus=3D"1"></DIV>
<DIV>Does anyone else run 87 in a high compression engine, or have I =
gone off=20
on a fool's errand here?</DIV></DIV></BLOCKQUOTE></BODY></HTML>
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