James,
I made a cleanup cut on the head and removed 10 thou from the block of my
.030 overbore 948 engine in my Bugeye. This was apparently enough to warrant
premium gas to keep the engine from overheating every time I stop at a traffic
light. Every other tank I add 2-3 gallons of 110 octane leaded racing fuel from
Union 76. It keeps the octane rating high and also imparts lead to the valve
seats while lubricating the guides. This car is not my daily driver. If it
was,
I would machine the head to restore the original compression ratio. Played hell
with the Judson that I was running last year. I had to run a 50-50 to 40-60 mix
of premium to 110 racing fuel to preclude detonation and run cooler. In other
words, yes I believe it IS that easy, just using premium gas to stop the run-on.
Otherwise you might want to sleeve the bore to original diameter and machine the
head to drop the CR. I know what my choice would be.
James Gruber wrote:
> I've had Bugsy my 68 Sprite with a '66 1098 engine on
> the road since late March. I never thought to ask
> anyone what type of gas to put in and assumed that
> this little old 1098 would run fine on regular. First
> tank of gas in Bugsy was a tank of Premium to help
> burn up the old gas that was in the tank initially.
> Subsequent tanks of gas were regular. Over the past 2
> -3 months Bugsy has been driven 2-300 miles around
> town and as I have expounded to the list, had a
> problem with dieseling. I changed plugs, retarded the
> timing, noticed that I had a vacumn leak around the
> throttle shaft of the front carb that I've attempted
> to seal up. Problem resolved at least temporarily. In
> general tried to get Bugsy to a better state of tune.
> At the same time dieseling problem continues to go on
> and on. Sometimes I have to resort to putting it in
> 4th gear and ease out the clutch in order to get it to
> stop. Very annoying and embarassing to listen to the
> engine run on and on.
>
> Today on a whim, I filled Bugsy up with Premium and
> added 1/2 can of lead substiture. Drove Bugsy 6-8
> miles fairly hard down some country roads and pulled
> into the driveway. Turned off the engine, it continued
> to run for about two-three revolutions of the engine
> and shut down. No sputtering, no run on, no dieseling.
> Start up was a snap with no loaded up engine from
> unburnt fuel. It can't be this easy can it. Simply
> change to premium gas.
>
> Engine definitely feels peppier. Will be curious to
> see what a change in gas grade does to fuel mileage.
> Right now Bugsy has been getting about 20 mpg but my
> foot seems to be in it most of the time listening to
> Bugsy run up in second gear listening to the glass
> pack make really nice sounds.
>
> That leads to another question. Could Bugsy now need
> premium as a result of head being milled and
> compression ratio being raised. No idea on this one
> and P.O. can't supply an answer on this one either. Is
> there any way to tell other than pulling engine apart
> and measuring volume of the combustion chanbers?
>
> Thanks again for your help.
>
> =====
> Jim Gruber
> Bugsy '68 Sprite (future Bugeye in disguise)
> Dayton, OH
> Yahoo! - Official partner of 2002 FIFA World Cup
> http://fifaworldcup.yahoo.com
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