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Terry,
I think Geo has the best answer here. Try regular and listen for knocking.=
No knocking, all is good, don't worry about it. (That last sentence is s=
trictly my opinion!!! Get information from others who know more to come to =
your own conclusion.) Compression is what causes knocking. But compressio=
n ratio of the engine is not the bottom line. The actual compression you g=
et in the cylinder and when your spark plug fires is the bottom line for kn=
ocking. Modern engines run higher than 9:1 compression ratio and run fine =
on regular gas. That's because with modern electronics the ignition can be=
adjusted on the fly. With these old engines, the cam also plays a major r=
oll in how much compression you actually have in your cylinder. If you hav=
e 2 engines with the same compression ratio, a mild cam can run well on reg=
ular gas and a hotter cam will knock on regular gas. That is because the m=
ild cam is opening and closing at different positions in the stroke compare=
d to a hotter cam allowing for lower total compression of the gases in the =
cylinder. Compared to the hotter cam.
Creig
________________________________
From: Triumphs <triumphs-bounces@autox.team.net> on behalf of Geo Hahn <ahw=
ahneetr@gmail.com>
Sent: Sunday, September 23, 2018 9:51 AM
To: TERRY SMITH
Cc: Triumphs
Subject: Re: [TR] Octane
Terry -
I rather think it was due to compression ratio more than anything else. Bu=
t you may just have to experiment a bit to see what works (adjusting advanc=
e, listening for ping).
My TR4 uses premium at off-brand stations but seems okay with regular from =
Shell or Chevron. My TR3A doesn't seem to care what I put in it, runs fine=
on almost anything.
Geo
rryrs@comcast.net>> wrote:
Just curious. Why is Premium gasoline recommended for a TR3 (and I suppose=
other Triumphs?)while regular is just fine for other vintage cars. I know=
it's to prevent knocking, but how and why? Does it have to do with being =
a short-stroke engine or something?
Thanks, everyone,
Terry
Archive: http://www.team.net/pipermail/triumphs http://www.team.net/archiv=
e
tr@gmail.com
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<body dir=3D"ltr">
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
Terry,</div>
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
<br>
</div>
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
I think Geo has the best answer here. Try regular and listen for knoc=
king. No knocking, all is good, don't worry about it. (That las=
t sentence is strictly my opinion!!! Get information from others who know m=
ore to come to your own conclusion.) Compression
is what causes knocking. But compression ratio of the engine is not =
the bottom line. The actual compression you get in the cylinder and w=
hen your spark plug fires is the bottom line for knocking. Modern eng=
ines run higher than 9:1 compression ratio and
run fine on regular gas. That's because with modern electronics the =
ignition can be adjusted on the fly. With these old engines, the cam =
also plays a major roll in how much compression you actually have in your c=
ylinder. If you have 2 engines with the same
compression ratio, a mild cam can run well on regular gas and a hotter cam=
will knock on regular gas. That is because the mild cam is opening a=
nd closing at different positions in the stroke compared to a hotter cam al=
lowing for lower total compression of
the gases in the cylinder. Compared to the hotter cam.</div>
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
<br>
</div>
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
Creig</div>
<div style=3D"color: rgb(0, 0, 0); font-family: Calibri,Helvetica,sans-seri=
f; font-size: 12pt;">
</div>
<hr tabindex=3D"-1" style=3D"display:inline-block;width:98%">
<div id=3D"divRplyFwdMsg" dir=3D"ltr"><font color=3D"#000000" face=3D"Calib=
ri, sans-serif" style=3D"font-size:11pt"><b>From:</b> Triumphs <triumphs=
-bounces@autox.team.net> on behalf of Geo Hahn <ahwahneetr@gmail.com&=
gt;<br>
<b>Sent:</b> Sunday, September 23, 2018 9:51 AM<br>
<b>To:</b> TERRY SMITH<br>
<b>Cc:</b> Triumphs<br>
<b>Subject:</b> Re: [TR] Octane</font>
<div> </div>
</div>
<meta content=3D"text/html; charset=3Dutf-8">
<div>
<div dir=3D"ltr">Terry -
<div><br>
</div>
<div>I rather think it was due to compression ratio more than anything else=
. But you may just have to experiment a bit to see what works (adjust=
ing advance, listening for ping).</div>
<div><br>
</div>
<div>My TR4 uses premium at off-brand stations but seems okay with regular =
from Shell or Chevron. My TR3A doesn't seem to care what I put in it,=
runs fine on almost anything.</div>
<div><br>
</div>
<div>Geo</div>
</div>
<div class=3D"x_gmail_extra"><br>
<div class=3D"x_gmail_quote">On Sun, Sep 23, 2018 at 6:26 AM, TERRY SMITH <=
span dir=3D"ltr">
<<a href=3D"mailto:terryrs@comcast.net"; target=3D"_blank">terryrs@comcas=
t.net</a>></span> wrote:<br>
<blockquote class=3D"x_gmail_quote" style=3D"margin:0 0 0 .8ex; border-left=
:1px #ccc solid; padding-left:1ex">
Just curious. Why is Premium gasoline recommended for a TR3 (and I su=
ppose other Triumphs?)while regular is just fine for other vintage cars.&nb=
sp; I know it's to prevent knocking, but how and why? Does it have to=
do with being a short-stroke engine or something?
<br>
<br>
Thanks, everyone,<br>
Terry<br>
** <a href=3D"mailto:triumphs@autox.team.net";>triumphs@autox.team.net</a> *=
*<br>
<br>
=3D"noreferrer">
Archive: <a href=3D"http://www.team.net/pipermail/triumphs"; target=3D"_blan=
k" rel=3D"noreferrer">
http://www.team.net/pipermail/<wbr>triumphs</a> <a href=3D"http://www=
.team.net/archive" target=3D"_blank" rel=3D"noreferrer">
<br>
hs/ahwahneetr@gmail.com" target=3D"_blank" rel=3D"noreferrer">
http://autox.team.net/mailman/<wbr>options/triumphs/ahwahneetr@<wbr>gmail.c=
om</a><br>
</blockquote>
</div>
<br>
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