[Healeys] Octane Ratings

Mark Schneider mandmschneider at comcast.net
Fri Oct 2 09:20:17 MDT 2009


Listers,

Several years ago I was fighting engine knock in my BJ8.  The engine  
now has 120,000 miles on it and never been rebuilt.  The compression  
now averages about 158 psi for all six cylinders.  I tried every  
octane booster and pump gas cocktail I could find, all to no avail.  I  
adjusted timing and did everything I could think of to stop it.   
Finally, one of the local racing shops suggested trying a mixture of  
leaded racing gas and pump gas.  I was given a nomogram by which one  
could select a desired octane rating and thereby determine the ration  
of race to pump gas.  To obtain a calculated 97 octane I have used one  
(1) gallon of 110 rated leaded race fuel to six (6) gallons of pump  
gas.  I have been running my Healey on this fuel mix for about fifteen  
years.  Is it a little expensive?  Yes.  Does my engine ever knock or  
ping?  No, never unless I back off of this mixture.  Does my engine  
run on (diesel) and require dragging the clutch while in gear during  
shut down? Never.  At the outset of using this formula I conducted a  
complete engine tuning.  I checked the carburettors adjustment with a  
Colortune. and set the burn to a very slight richness.  My Healey runs  
very smoothly and sounds fantastic.  Finding a source of leaded racing  
fuel is a bit of a challenge.  I have found that a local motorcycle  
repair shop is the best source of race gas.

Marks3
'66 BJ8


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