FlagEngland.gif (9780 bytes)     Button_TRIUMPH.gif (4045 bytes)     Triumph_most_popular_cars.gif (7221 bytes)


Button_back.gif (2137 bytes)  Button_Specs.gif (2172 bytes)  Button_colors_sm.gif (2153 bytes)  Button_techinfo_sm.gif (2150 bytes)   Button_40dcoe_gr.gif (4358 bytes)   Button_books.gif (2149 bytes)


Webers are often maligned. This is more often due to poor installation by inexperienced and impatient mechanics. But Webers are not rocket science, nor do they require that one be an experienced mechanic. What is required is a good deal of common sense, a methodical and patient approach, and some understanding of the air-fuel system and its combustion.

For every owner I have spoken with who have expressed their nightmare with Webers, there are 2-3 owners who have glowing remarks. The only real complaint that can be levelled at Webers is their consumption of fuel. Expect 15-18mpg in a TR6 that is driven at a more-than pedestrian pace.

Task: to provide an electronic archive of all accumulated knowledge of fitting a set of Weber 40DCOE-2 Webers to a Triumph TR250/TR6. Sources include books, email, interviews and web-sites.


Reference D G H I J L
Haynes 27 4.5 1.30 F2 1.60 0.50 F11 0.45 2.00
TT/Moss (*) 28 4.5 1.15 F16 1.75 0.50 F9 0.5 -
TT/Moss 30 4.5 1.25 F16 1.80 0.50 F9 0.35 -
Phillips (*)  30 4.5 1.55 F11 2.00 0.45 F9 0.50 -
Kantarjiev (*) 28 4.5 1.10 F2 1.60 0.45 F9 - -
Fitzgerald  27 4.5 1.20 F11 1.60 0.49 F9 0.60 1.75
Bickel  28 - 1.20 F11 1.60 F9 - -
Nugent (1) 28 4.5 1.20 F16 1.75 0.50 F9 0.35 -
Nugent (2) 30 4.5 1.20 F16 1.80 0.50 F9 0.35 -
Nugent (3) 33 4.5 1.25 F16 1.85 0.50 F9 0.40 -
Bickel (4) - - 1.20 F11 1.60 F9 - -
Mains (5) 30 - 1.20 F11 1.60 0.60 F9 0.50 -

D = choke size
E = auxiliary venturi
F = main jet
G = emulsion tube
H = air corrector jet
I = idle jet
J = accelerator pump jet
K = accelerator pump inlet valve with exhaust orifice = closed
L = needle valve

( 4 ) Larry Bickel provides the following:
"... and most important- choke tubes ( venturis )- 28mm Disconnect the choke cable- it isn't needed. Make sure that the float level is correct. Also I run 26 degrees total advance on the distributor (10 + 16)."

( 5 ) Bob Mains ( Prez, Buckeye Triumphs ) also adds:
"The cam specs: Intake-Open/Close-36' BTDC/ 69' ABDC Exhaust-72' BBDC/33' ATDC Lift 405 Dur 285..... The multiple spark feature of the MSD 6AL Ignition module made a BIG difference for the fuel richness/plug fouling, .055 spark plug gap for NGK BPR6ES, using standard points/gap and a Lucas Sport coil. Timing is about 28' advanced.......Roller rockers are 1.50:1. Stock exhaust headers and freeflow, dual mufflers. Compression-9.5:1. We tried the 45F9 and 60F8 idle jets but didnt work. Also tried 180 air,F16 Emulsion and 125 Main jets. Initially had 40 Accel pump jets. Again no luck."

All owners recommend that the accelerator pump inlet valve with exhaust orifice ( back bleed ) be closed (0.00).

wpe6.jpg (2190 bytes)

Fuel pressure

Webers are very sensitive to variations in fuel pressure and quality. Install the biggest and best fuel filter you can buy (the FRAM HP-1 is recommended). If your Webers seem to lose their edge with time, it is probably because of dirt in the jets. Remove each jet and blow it clean. Only 10 minutes work, but you will be rewarded with pristine performance again.

The standard Triumph fuel pump is totally inadequate. Webers need lots of fuel flow but can't stand pressures over about 5psi (3-4psi is a good number). The shiny-toy pressure regulators sold in discount stores cannot flow enough fuel to keep three big float bowls full at high engine speed, unless you use one per carb. An unregulated stock fuel pump will put out up to 8psi at hi-rpm which will sink the floats, causing other problems.

wpe6.jpg (2190 bytes)


Discussions with people who have successfully implemented multi-Weber installations, it seems that the key issue to resolving the Weber's lack of popularity amongst amateur tuners is the cam. Matching the cam to the Webers appears to be of prime importance, because then nominal jetting can be used.

What constitutes a good cam? It appears that Webers prefer cams with long duration and small lift. This makes sense because there is litte vacume provided in the DCOE/IDA design, and the long duration is needed as a compromise.

The following cams have been used by folk who have provided the jetting information above. I do not have the specs on the cams (I will add them later), and the list here is not an endorsement for any of the cams. (1) "Road" cam
(2) "Fast road" cam
(3) "Sprint"
(4) Vitesse, "Road" cam, via Leon Guyot
(5) Vitesse, "Sprint cam", via Leon Guyot
(6) Steve Phillips, via Leon Guyot
(6) GT6, Chris Kantarjiev (cak@dimebank.com), via Leon Guyot

wpe6.jpg (2190 bytes)


Weber Carburator Manual, Haynes Techbook, 1995
Triumph TR6 Performance: Parts, Sources and Procedures for the Enthusiast, John P. Fitzgerald, 1996
Allen Nugent (A.Nugent@unsw.edu.au), 8/98
Larry Bickel (ljbtvr@aol.com), 4/97
Leon F Guyot (GuyotLeonF@aol.com), 4/97
Bob Mains (bob.mains@ode.state.oh.us), 9/00

From : http://www.hottr6.com/triumph/ Shane's Triumph page


wpe6.jpg (2190 bytes)

Button_TOP.gif (2090 bytes)

wpe3.jpg (2126 bytes)