26 May 1996
FROM: TRIA73@aol.com
RE: Dual SU Fuel Bowl Float Levels
On Thu, 23 May 1996, Charlie Brown of Capital Triumph Register questioned
the set up of dual SU fuel bowls for a Spitfire 1500. I have a 1973 Spitfire
which I have been trying to adjust the carbs (dual SU HS4's) for the past 4-5
months since recently completing an engine rebuild. Due to the installation
of new motor mounts the engine has approximately a 4 degree tilt towards the
rear of the engine compartment which resulted a very low fuel level in the
rear carb. Charlie has been assisting me if rectifying this condition in
which the fuel level in the rear fuel bowl was 1/4" lower than the front. We
tried adjusting the float level and even added an extra gasket on the fuel
bowel cover in an effort to raise the fuel level in the rear carb without
success. With this condition the engine would bog down at RPM's higher than
3000. Paul Geithner, also a CTR member, recommended that we try using an AUD
1310 fuel bowl since it had a slight offset and would help to raise the fuel
level in the rear carb. After obtaining a AUD 1310 fuel bowl at the Carlise
Import Show a few weeks ago I finally swapped the rear fuel bowls and what a
difference. The fuel level in the both jets is about the same and I can
finally can rev the engine out to 4500-5000 RPM. I'm currently using "AAB"
needles and running a Kent "Fast Road" cam with 20,000 over pistons and
headers.
As Charlie questioned previously, how did the Brit's ever get their stock
1500's with this set up perform well on the other side of the pond ???
Randy Dunn
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