Zenith 30VM C1207 Jets?

Keith Andrews · Post by **Keith Andrews** » Sat Feb 17, 2007 12:45 am

What are the correct jets for the Bradford CC Zenith 30VM C1207 Carb?
I have 4 Bradford carbs here all with very differnt jetting.
Mains from 70 to 95
Compensator 70 to 90
Slow run are all 50
And capacity tube all 24

Bryan Walker · Post by **Bryan Walker** » Sun Feb 18, 2007 3:00 am

Fromm the JCC handbook for bradfords:

CA
Zenith Type 30 VEFH
Choke 26
Main 95
Compensator 75
Slow running 45
Progression 150
Needle seat 1.75 mm

CB
Zenith Type 30 VM
Choke 25
Main 95
Compensator 80
Slow running 50
Progression 100
Needle seat 1.5 mm
Screw over capacity tube 2.8 mm

CC
Zenith Type 30 VM
Choke 25
Main 95
Compensator 70
Slow running 50
Progression 120
Needle seat 1.5 mm
Screw over capacity tube 2.4 mm

(Note - Early CC models had Compensator 50. Capacity tube screw 2.0 mm, and a deflector.)

Spitting-Back: In extreme conditions the size of main jet should be increased to 95 and
progression jet to 150 the choke screw being replaced with the extended type. Always set the
slow running with the butterfly closed It may be possible by Maladjustment of the slow running, to
obtain tick-over with the butterfly slightly open and this will increase the tendency to 'spit-back' by
causing an excessive drain on the capacity well It will also increase petrol consumption

Bryan

Keith Andrews · Post by **Keith Andrews** » Sun Feb 18, 2007 4:05 am

Once again Brian Thanks...
Should have the new engine, gearbox, clutch Pressure plate in soon, and needed the factory specs for a starting piont.
Couple questions thu...think its another termlogly thing??
Needle seat? is that the mixture screw adjustment?
And
Progression? what/where is that?

4 barrel holleys and Impco LPG carbs I know my way around, this 'old' stuff Zenith stuff is a learning curve.
All I have is the JCC manuals and the pitman's Jowett handbook which are very good, but some of the finer pionts are not there or " send to the local service shop" These days Bradford Service shops are few and far between

Keith Andrews · Post by **Keith Andrews** » Sun Feb 18, 2007 4:22 am

Main #31
Compensator #33
Slow run #38
Capacity #39
Idle mixture #9
Throttle Stop screw #22

Bryan Walker · Post by **Bryan Walker** » Sun Feb 18, 2007 5:44 am

Needle seat is part of the needle valve-size stamped on the valve.
Progression jet is on the side of the carb.- follow the air regulator screw tube down and is in line with throttle spindle.
What is not given is the valve seat washer thickness, Jav is 1mm.

Bryan