Chris,
That "reformulated" gasoline that I wrote about is, unfortunately, not
limited to CA. We have the stuff here in CT and in a number of other
states. The GOF where I heard about the gas and its effect on the
Colourtune was in MG, so one must assume that the foul fluid is inflicted
on a large number of MG drivers.
Bob
On Mon, 18 Oct 1999 08:22:23 -0700 Chris Attias <cattias@cats.ucsc.edu>
writes:
>Neil,
>
>I've pretty much eliminated the ignition as a factor in the wierd
>Colortune readings. I have a Pertronix electronic ignition replacing
>the points--dwell set by the electronics in the Hall-effect switch.
>Both vacuum and centrifugal advances are working. Putting the
>timing gun on it, the timing looks dead even--no jumping around.
>Valves set to stock .015 intake and exhaust cold. I have been using
>standard SU dashpot oil--Penrite, and did the test with a fully warm
>engine at 68 degrees F. air temp.
>
>The two unknowns so far are the cam pattern/condition and the
>California Reformulated Gasoline. The cam thing is only a theory at
>this point--that greater valve overlap changing the nature of the
>proper mixture enough to change what you see through a Colortune. I
>would think the problem on my car would be with cam pattern rather
>than wear, as the same condition is observed in all cylinders. Has
>anyone with a hot street cam or race cam set their carbs with a
>Colortune?
>
>Last and best thought I've seen came from Bob Howard--that California
>gasoline, formulated with MTBE and other oxygenates, alters what you
>see at the correct mixture point. Evidently this has been a point of
>discussion with serveral people. Maybe I should import some 49-state
>gas and try this one out!!
>
>Chris Attias
>'64 MGB
>'84 Alfa Romeo GTV-6
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