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Re: Re.: MGA 1600 timing, vacuum advance

To: thorpe@kegs.saic.com
Subject: Re: Re.: MGA 1600 timing, vacuum advance
From: jhoward@argus.lowell.edu (James D. Howard II)
Date: Wed, 19 Jul 95 14:24 MST
   > 
>   The original factory service manual for my '67 MGB makes dire predictions
>   of what will happen if less than 98 octane gas is run in the engine.  I'm
>   told by people in the know that the way octane ratings is calculated has
>   changed and that the old 98 octane is the same as the new 93 octane.  My
>   car has the high compression engine as (I'm told) did all of the MG's 
>   imported to the states.  Are you sure yours has the low compression engine?

There are two ways of calculating octane.  The one you see on pumps in
the USA these days is the average of the two.  If you look at the
label, it says R + M / 2.  The R stands for Research Octane.  I can't
remember what the M stands for.  The 98 octane called for was one or
the other of these two.  My 67 BGT needs the 93 octane to run right -
otherwise, it pinks and diesels.  It is a brand new engine.  My 74 MGB
has the low compression engine.  That was BL's solution to the running
on problem.  It gets much worse gas mileage (18cty/25hwy vs. 25cty/32
hwy), and has a lot less power.  It also has 150,000 miles on it.

James

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