[Healeys] Gasoline Octane

[PG]

Higher Octane Fuels burn slower the idea being that in higher compression
engines or in exceptionally hot chambers, the flame front does not detonate
prior to the piston being past TDC.

So, yes the dieseling could definitely be related to the lower octane and
the fuel is combusting off a hot spot in one or more of the chambers.

With respect to misfiring, if you mean "knocking" then yes, that is a
symptom of too low of octane (or too advanced of timing).....not a good
thing to do for a continued period of time...puts lots of stress on the
engines and can lead to cracked or damaged pistons.

To get through the tank of fuel either add an octane additive or retard the
distributor until you don't get the "knocking".

Alternatively, the fuel mixture could be too lean which will raise the
temperature of the chamber and can also cause diesling.....is the care
burning hot?? 

Paul


-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of Kenny J
Sent: Sunday, June 07, 2009 2:55 PM
To: Healeys Healeys
Subject: [Healeys] Gasoline Octane

Today I went on a little drive down the CA coast south of SF (Pacifica -
Half
Moon Bay).  The weather was incredible.  The only problem with todays drive
was my engine began to misfire while accelerating (more than 1/2 throttle).
I
also had some dieseling after turning off the ignition.  Normally I use 91
octane but when I filled up (10 gallons) this morning I accidently put in
87.
Could that be the source of my misfiring/dieseling?  Thanks.



Kenny

'61 BT-7

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