The Weber 28/36 exploded diagram

This carburettor is used on the 1500 G.T. Cortina, and is often fitted as a tuning modification to other Fords.

Note: I do not know the origin of the second diagram. 

If you are the copyright holder, I apologise.

To save yourself some grief, there is a return spring shown on SOME versions of the 28/36 drawing, in SOME versions of the official Ford Workshop Manual. I have no evidence it actually exists! It's not fitted to 5 28/36s in my possession. Gower and Lee checked with Weber and can't find any trace of it.

Of course, if you know different, contact me.

Well, somebody knows different! 

""The throttle return spring on the secondary throat of the MkI GT Weber 28/36 DCD is in fact not a myth, there's one on the original carburettor on my Oz built 1967 MkI GT.  It may not be in the parts book but it is definitely there.  MkI and MkII Cortinas were coming down the line side by side at the end of the MkI production run and there were a number of "on the run" engineering decisions about what was needed to make the car complete at the end of the run."" -- Ross Gardiner.

And

""Just had another thought regarding that spring, for homologation for racing we have always been required to have duplicated throttle return springs down this way, I'm tipping the concept was not one we dreamt up on our own.  It possibly has a bit more to do with competition rather than road use."" -- Ross Gardiner

Thanks Ross!!

webspring.jpg (48716 bytes)

Above, illustration of the mythical (??) throttle return spring.


weber2836.jpg (66963 bytes)

Above, diagram showing parts of 28/36 carburettor.

Key to the diagram:-

1 Carburettor cover 23 Intake & discharge valve 42 Spring 65 Starting device cover
2 Stud 24 Return spring 43 Spring 66 Shaft
3 Cover retaining screw 25 Pump control lever 44 Throttle adjusting screw 67 Starting valve
4 Lock-washer 26 Washer 45 Primary throttle 68 Spring
5 Starter plunger seat 27 Toothed ring 46 Throttle retaining screw 69 Spring guide & retainer
6 Starter plunger 28 Washer 48 Stop sector 70 Pump delivery valve
7 Spring 29 Spacer 49 Primary shaft 71 Gasket
8 Filter 30 Lock-washer 50 Bush 72 Pump jet
10 Gasket 31 Retaining nut 51 Primary sector 73 Primary air correction jet
11 Filter plug 32 Spacer nut 52/ 52A Alternative throttle control levers 73A Secondary air correction jet
12 Cover gasket 33 Pump control cam 53 Return spring 74 Primary emulsion tube
13 Needle valve gasket 34 Primary idling jet 54 Secondary shaft 74A Secondary emulsion tube
14 Needle valve 34A Secondary idling jet 55 Secondary throttle 75 Primary choke
15 Fulcrum pin 35 Sealing ring 56 Retaining screw 75A Secondary auxiliary venturi
16 Float 36 Idle jet holder 57 Starting device 76 Secondary choke
17 Spring retaining plate 37 Gasket 59 Screw 76A Secondary auxiliary venturi
18 Operating rod 38 Primary main jet 60 Control lever 77 Carburettor body
19 Spring 38A Secondary main jet 61 Spring washer
20 Starting Air Jet 39 Main jet holder 62 Nut
21 Starting fuel jet 40 Progression hole inspection screw plug 63 Return spring
22 Pump piston 41 Idle mixture adjusting screw 64 Screw

 


Settings for 1500 G.T. Cortina MK1

  Primary Secondary
Venturi Diameter/ Choke 26 27
Auxiliary Venturi diameter 4.5 4.5
Main Jet 140 155
Air Correction Jet 230 180
Emulsion Tube Jet F 30 F 30
Slow running/idling  petrol jet 50 70
Slow running air jet 200 70
Progression holes 2 x 120 1 x 120
Slow running volume control port 1.5 mm --
Air bleed in throttle plate -- 1 mm
Needle valve

1.75 mm

 
Float Travel

8.5mm

 
Starter petrol jet

100

 
Starter air passage

6 mm diameter

 

Note: These are the official Weber/Ford settings. Settings may vary for each individual vehicle.


Other set-ups I have found  (from various sources):-

Engine Carburettor Modifications Primary Settings Secondary Settings
         
1500 G.T. 28/36 DCD Modified head, cam & exhaust Choke 27

Main jet 150

Air correction 220

Emulsion Tube F30

Pump 70

Idling jet 60

Choke 28

Main jet 160

Air correction 190

Emulsion Tube F30

Pump 70

Idling jet 70

Australian GT 500 28/36 DCD Modified head, cam. Choke 27 Choke 29

Main jet re-drilled to 135

 

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Page last updated:- 19 May, 2006 15:21