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Pondering the possibilities!

To: "'Power British Perfrormance Parts, Inc.'" <britcars@powerbritish.com>, "'Triumphs List'" <triumphs@Autox.Team.Net>
Subject: Pondering the possibilities!
From: "Wages, Jeffrey" <bzw8@cdc.gov>
Date: Thu, 29 Oct 1998 15:31:56 -0500charset="iso-8859-1"
I've seen all the posts regarding the proper plugs, timing, etc. for TR's,
speciffically 6's. What I wonder now is, do the original specs for the TR's
plug type, gap, timing etc. change with the introduction of no-lead gas?

Thanks in advance,

Jeff Wages,
'71 TR6 

> -----Original Message-----
> From: Power British Perfrormance Parts, Inc.
> [SMTP:britcars@powerbritish.com]
> Sent: Thursday, October 29, 1998 2:43 PM
> To:   triumphs@autox.team.net
> Subject:      Re: TR-2,3,4A - Retard timimg for use with 92 octane gas?
> 
> 
> John,
> 
> You should use the lowest octane fuel you can provided the engine shows no
> signs of
> detonation.  Octane actually makes the fuel harder to ignite, hence it's
> use in very high
> performance engines.  These engines make their power from the compression,
> not the octane
> in the fuel.  An engine's power output is a funtion of the pressure
> created in the
> combustion chamber above the piston.  The more compression, the higher the
> pressure at the
> moment of ignition and the more "push" down on the piston.
> 
> As the air/fuel mixture is compressed, the temperature goes up.  The more
> compression, the
> higher the temp.  At some point, the fuel may spontaneously ignite prior
> to the spark plug
> firing.  This is detonation and it is very bad for an engine because it
> often occurs just
> before the plug fires.  You then end up with two flame fronts in the
> cylinder that crash
> into each other which can crack pistons and rings, etc.  Most often in TR
> engines, I find
> cracked ring lands (the area between the topmost two rings) to be the most
> likely victim
> of detonation damage.
> 
> Octane is added to the fuel to reduce the chances of detonation.  In doing
> so it actually
> slows the combustion process.  The lower the octane, the faster the flame
> front spreads
> thoughout the combustion chamber - this yeilds higher cylinder pressure
> just after the
> piston passes TDC, and theoretically more power for any given compression
> ratio provided
> there is no detonation.  Bottom line - for best performance, run the
> lowest octane you can
> that does not cause detonation.
> 
> As far as timing goes, you must do some experimentation to find the best
> combination for
> your engine.  Most motors will make good, reliable power with a full
> advance of 28 - 34
> degrees total timing.  Double your distributor advance, then subtract from
> your desired
> total timing to find your initial timing.  (e.g.  If your distributor
> weights are stamed
> with a 12, then that is 12 degrees distributor advance. 12 degrees x 2 =
> 24   28 - 24 = 4
> degrees before top dead center initial timing.)  You must make timed runs
> and compare
> results to find what is the best for you.  The amount of advance the
> engine will tolerate
> depends on the quality of fuel you're using, the general condition of the
> engine, and the
> atmospheric conditions in which you live.  First, make sure your carbs are
> tuned properly
> and that your car is fully warmed up by driving for a few miles.  Then
> find a flat length
> of secluded roadway to make some tests.  Start on the low end of the
> scale, set your
> timing, and make a timed acceleration run in top gear between 30 - 60 mph
> (helps to have
> an assistant in the car with you to record times with a stopwatch).
> Advance the timing a
> few degrees (try 2 degrees to start) and retest.  If at any point, you
> hear detonation,
> stop the run and retard the timing until the detonation goes away.  You
> will find your
> runs get faster to a point and then fall off again.  If you continue
> advancing, detonation
> will set in.  Once you find your fastest timed run, set the timing to that
> figure provided
> it is at least 4 degrees away from the point at which you heard
> detonation.
> 
> I bet if you spend an afternoon experimenting, you'll be surprised at how
> much better your
> car will run afterward!
> 
> BTW if you find that the car idles too high after setting to your best
> performance, you'll
> need advance weights with more timing built in to bring the idle back down
> again.
> 
> Regards,
> 
> Brian Schlorff
> Power British
> http://www.powerbritish.com/~britcars
> 
> 
> 
> John Cowan wrote:
> 
> >   Spec for timing of Triumph four bangers is 4 degrees before true dead
> > center.  But this was written with 96 octane gas in mind and required.
> Is
> > anyone retarding spark to two or zero degrees as a matter of course in
> > order to deal with the the 92 octane gas that is the best grade
> available?
> > This was recommended to me.
> >    Thanks.
> > John Cowan
> >
> > BTW, I toy with the idea of using a mixture of 92 octane and 100 octane
> > Aviation gasoline.
> >
> > Visit - In Their Own Words Website - an on-line non-commercial
> publishing
> > experiment, plus movie reviews, articles and Left/Progressive links at:
> >                            http://home.earthlink.net/~jfcowan
> 
> 

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