Weber 45 DCOE Carburetor Setup

Part numbers and initial settings for this popular & effective, but tricky to tune, side-draft carb conversion.

Written by Skye Nott – 2006-04-02
How-To Library > Carburetors and Fuel Section

The Weber 45 DCOE is a popular choice for MGB owners looking to unleash a bit more power in the admittedly rather prosaic (but reliable) B-Series engine.

This was the carb of choice among factory entries and racers in the heyday of the MGB, and coupled with the reliability inherant in the design, it powered the B to many finishes above more tempermental entries by other sportscar manufacturers of the time.

Combined with a large-bore block and a modern high-flow head, the 45DCOE can really make a difference on the dyno. Whether or not this conversion is cost effective considering the expense and the return in HP, is up to you.

Under normal driving conditions, it is my opinion that a well-maintained pair of HS4 or HIF4 SU carburetors is just as good, if not better than, a 45DCOE, considering the complication and expense that tuning these race-application carbs can require.

If you do not have the expertise or equipment (such as a wide-band oxygen sensor and rolling road) to tune these carbs properly, you may be chasing after settings endlessly - the number of variables in tuning these carbs is large and requires an understanding of the theory of operation.

The settings listed here are a starting point only, from which specific modifications will most likely be required.

45 DCOE 152 Carburetor
Part # 19600.060
Special Tuning Kit # C-AJJ 3312

Weber 45 DCOE 152 Carburetor - Part # 19600.060 - Special Tuning Kit # C-AJJ 3312

Fig	Qty	Description	Part Number	Fig	Qty	Description	Part Number
1	1	Filter Cover	61002.010	46	2	Cup Washer	58000.006
2	1	Filter Cover Gasket	41530.024	47	3	Spring	47600.007
3	1	Filter Element	37022.010	48	2	Vacuum Screw	64590.008
4	1	Jet Inspection Cover	32376.003	49	2	Pump Jet Gasket	41535.021
5	9	Screw	64700.001	50	1	Spring	47605.012
6	1	Jet Inspection Cover Gasket	41550.002	51	1	Spring Plate	52210.006
7	1	Top Cover Gasket	41715.011	52	1	Throttle Stop Screw	64625.012
8	1	Needle Valve	79503.200	53	1	Pump Plunger	58602.003
9	1	Float (plastic)	41030.034	54	2	Starter Valve	64330.003
10	2	Emulsion Tube Holder	52580.001	55	2	Starter Valve Spring	47600.105
11	2	Air Corrector Jet	77401.*	56	2	Idle Mixture Screw	64750.003
12	2	Idle Jet Holder	52585.006	57	2	Pump Jet	76801.*
13	2	Emuslion Tube	61450.*	58	2	Pump Jet Oring	41565.009
14	1	Stud	64955.007	59	2	Pump Jet Cover	61015.008
15	2	Main Jet	73401.*	60	1	Pump Rod Spring	47600.064
16	2	Idle Jet	.	61	1	Pump Rod	10410.015
17	2	Auxillary Venturi	69602.450	62	2	Starter Jet	75507.085
18	2	Air Horn	52840.001	63	2	Pump Valve Ball	58300.003
19	4	Air Horn nut	34705.004	64	2	Stuffing Ball	52730.001
20	4	Waasher	55525.010	65	2	Retaining Screw	58070.008
21	4	Air Horn Tab	521550.012	66	1	Neddle Valve Gasket	83102.100
22	2	Main Venturi	72116.*	67	1	Fuel Union Gasket	41530.031
23	4	Stud	64955.110	68	1	Fuel Union	10536.035
24	2	Lock Washer	34710.003	69	1	Fuel Union Gasket	41530.024
25	2	Cap	14945.003	70	1	Fuel Union Bolt	12715.008
26	2	Air Bypass Screw	64750.002	71	2	Inspection Cover	61015.009
27	2	Lock Nut	34705.001	72	1	Float Pin	52000.001
28	2	Locking Screw	64830.006	73	1	Cable Clamp	64605.017
31	2	Lock Washer	55520.004	74	2	Starter Air Jet	77505.150
32	2	Throttle Shaft Nut	34710.003	75	1	Top Cover	31734.197
33	2	Throttle Plate	64005.044	76	1	Plate	52130.003
35	4	Throttle Plate Screw	64520.027	77	2	Washer	55510.128
36	1	Cover Gasket	41640.001	78	2	Bearing	32650.001
39	2	Screw	64750.009	79	2	Oring	41575.019
40	2	Screw	64700.004	80	1	Inspection Cover	52135.024
41	1	Pump Cover Gasket	41640.021	81	1	Gasket	41640.021
42	1	Cold Start Unit	32556.018	82	1	Pin	58445.001
43	1	Pump Exhaust Valve	79701.040	83	1	Cover	32374.008
44	2	Idle Mixture Screw Oring	41565.002	84	1	Pump Cam	45082.005
45	1	Throttle Lever	45048.007	85	1	Throttle Shaft	10005.438
* Please see Calibrated Parts Listing				86	1	Washer	55555.010

Weber 45 DCOE Initial Settings for MGB

45 DCOE Initial Settings
Main Venturi	36 ?	Auxillary Venturi	5.0 mm
Main Jet	1.85 mm	Air Corrector Jet	1.60 mm
Emulsion Tuber	F16	Idle Jet	0.60/F8
Needle Valve	2.25 mm (spring loaded)	Pump Jet	0.60
Pump Exhaust Valve	40 ?	Float/Cover Gasket Level	5 mm *
Chokes	40.0 mm
* When the level between the float and cover gasket is measured, it is important that the float is allowed to hang vertically. A false reading will be obtained if the lid is held horizontally.

Weber 45 DCOE Carburetor Notes

When fitting a 45DCOE to the B series engine, a special manifold will be required. The carb itself is mounted on synthetic rubber O-rings ("Thackeray washers") which absorb vibration and prevent the air-fuel mixture from being disturbed. A steady rod should be made up and connected to the rear engine plate.

Your Weber conversion will be most worthwile if you combine it with cylinder head modifications, a free flow exhaust system and a good air filter setup like K&Ns. Tuning is a complex affair and best done on a rolling road.

More information can be found in MG World No.7 (Oct/Nov 1998) and in Lindsay Porter's DIY Book - available in the MGExp Store

Weber 45 DCOE Diagram

Weber DCOE Parts Diagram

— Weber 45 DCOE Carburetor Setup —

Written by Skye Nott – Created 2006-04-02 Published 2006-04-02
Contents © Copyrighted and published under the following terms:
Released under the terms of the CC Attribution-NonCommercial-ShareAlike 2.5 License

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Member Comments on Weber 45 DCOE Carburetor Setup ↵

Rated 8 out of 10 based on 3 ratings

2013-10-25 21:29:01 # 12527

Comment by Barry Barnes

Rating: 8/10

This was a well-done article. By the way, where do you hook up your
vacuum advance hose that goes down to the distributor. I hooked it
up to the intake manifold (per advice from the guy I bought them
from - but doesn't vacuum drop on acceleration??? It seems I
would tap in on the carb side, maybe even near the air horns. There
are what appear to be knock-out plugs near the idle adjustment
screws; additionally, there are plugs on the carb body near where the
air horns hook up (sort of on the outer/lower side (about 270
degrees on the right side when viewing from the intake or air horn
inlets).

2018-02-27 16:16:13 # 48773

Comment by Shaun Johnson

tbtbu

2019-02-20 11:51:13 # 54708

Comment by Paul Zink

Rating: 8/10

Useful to have not only the exploded diagram but also the initial settings chart for a 45 DCOE.

2019-07-07 16:47:25 # 58072

Comment by Chris E

I would add that the MG initial settings is a good starting point (though a little rich in my opinion, unless the engine is also tweaked with aggressive cam, etc). BUT, the first thing one needs to do before any adjustments to a DCOE 45 152 is adjust the float level, which has an effect on all other adjustments. I personally have always used 7mm for the last 43 years on MGBs with great success, especially in the bottom and mid range.

2020-09-18 08:01:55 # 66118

Comment by alfred dawes

Rating: 8/10

Any one have MGC Triple(3) carb Set up using SK/OER/Weber Style 40/42/45mm TWM intake manifold tuning guides, base settings for the GGL/3.0L Six(6) cylinder??

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