Hi Joe,
The best Weber source I have found is Pierce Manifold in Gilroy, CA. (see the
monster list) Give them a call and they can set you up. But you should get
the essential books on the topic. Weber Carburetors by Pat Braden and the
other book of the same title by John Passini. At least a colortune is
essential. Some sort of realtime mixture meter (like a Gastester or a
Halmeter AF) would be best. I am CONVINCED that 90% of all problems people
have with Webers is from not setting them up right in the first place and too
much fuel pressure. 3.5psi MAX !! Measure it with an accurate gauge.
The most important thing to get right, right from the start is the correct
size main venturi (choke). My chart from the Passini book shows 28-30mm for a
1300cc engine with a 6000 rpm power peak. To get a starting rough main jet
size multiply the main venturi size by 4.
Even better, here's some complete suggestions.
------- 40DCOE x 2 (1300 Spit)----
choke (main venturi) 28 30
aux. venturi 4.5 4.5
emulsion tube F16 F16
main jet 115 115
air corrector 165 155
idle jet 45F8 45F8
pump 35
35
back bleed 0 0
And also:
Recently I obtained a set of Webers off a Spitfire-here's what I found:
Main Venturi 30
Aux Venturi 3.5
E Tubes F16
Main Jet 115
AC 165
Idle Jet 45F9
Pump Jets 40
Starter Jet 100F5
I'm converting my TR4A this fall (a prelude to EFI) and eventually my
Spitfire project car will have the Webers. Given the cost of converting these
days you might want to consider EFI.... a complete set of the above pieces
for two carbs costs about $275 (non-returnable). TWM makes throttle bodies
that bolt right on to the Cannon manifold and a Simple Digital Systems
controller box ought to have you up and running for $1500 or so.
Then again, used SU HS4's work pretty good too, and you could buy another
Spit with what's left over.... ;>)
GOOD LUCK!
Chris Lillja
'66 TR4A
'71 Spit MKIV (Soon to be a special)
'74 Norton Commando 850
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