DCOE / DHLA setup

[omichaelshar]

I have bought a set of DCOE 45 Weber and plan to fit them to the Sprint and compete in my first club event on 14 Feb.

The carbs came off a Sprint motor that has a similar state of tune to my own. The previous owner says they are setup too rich and are prone to flooding.

Hence, I would be grateful for advice on setting them up properly and would like to know what choke, jets and fuel pressure other people with twin DCOE or DHLA have used successfully.

Ideally, specific responses against the list below would be great.

Owen

Engine and state of tune:-
Carb Type, Model and Quantity:-
Main Jet Primary:-
Air Jet Primary:-
Idle Jet Primary:-
Float Needle and Seat:-
Main Venturi (Choke tube):-
Primary Emulsion Tube:-
Pump Bleed Back:-
Fuel pump type:-
Fuel pressure:-

[Troy ODoherty]

Hi Owen. I saw those on ebay on xmas day, was wondering who brought them. I put twin 45 DCOEs on my 8V in the middle of last year.If they are flooding you need to check the float level and the supply pressure. 4psi is about right plus or minus 1 psi.I put an electric pump under the car near the tank. you can hear the pump when you turn the ignition on, but once the engine is running it cant be heard.The pump is just a little transistor pump from Repco and is more than adequate for the job.
If the float levels are wrong then the whole mixture will be out. You must set these first. Then decice if they are rich at idle, then progression, then on the main circuit.
It sounds daunting but is actually simple enough if you follow the steps to setting them up. It took me about three hours to get mine right and I hadnt done a set of twin webers before. I have done a few 48 IDA down draugths on rotaries, but not for ten years or so.
There are some good books about on how to do it. Try Pitstop bookshop in perth, fast delivery(overnight to eastcoast)HP do a very simple and comprehensive book on everything you need to know.I will find my jetting list later today and post them for you.
I am currently setting up the quad 48DCOs to go onto the V8 in the rally car. If I ever get it back from the panel beaters.
Cheers Troy

[Beans]

The set up of Weber DCOE’s depends very much on the overall set up of your engine. They are not what you’d call easy to set up if you have to start from scratch.
Most important is the overall breathing of the engine;
• which filters do you use;
• what’s the length of the ram pipes and how are they radiused;
• what cam do you have;
• What have you done to the head (porting, valves etc.);
• what exhaust (manifold) do you have under the car.
So to sum it up the best way to go, is find someone who knows about Webers, has a rolling road and knows how to use it.

My engine has the following carburettors & set up;
• DCOE 45/152's;
• Chokes 36 mm;
• Aux. venturi 4.5 (if I remember correctly);
• Main jet 135;
• Corr. jet 170;
• Emulsion tube F11;
• Idle jet 0.55 F9;
• Acc. pump inlet BB40;
• Acc. pump jet P45;
Together with a STR091 cam profile (group 2 rally) and some breathing mods that produces between 152.5 and 165 BHP @ ±6000 rpm (measured at the rear wheels that is, so add approximately 20 BHP for flywheel horses ...)
One last bit of info, while setting up the carburettors we found out we got the best result by drilling some fine holes in the emulsion tubes …

Not quite sure about the fuel pressure. I have a Filter King pressure regulator between the fuel pump and carburettors (it’s a Nr.3 which works in the range between 0.2-0.3 bar) This regulator is on its factory settings.
I use a Facet Silver Top fuel pump, which delivers between 0.35-0.45 bar (123 ltr/hr).


<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC</font id="blue">
<font color="red">http://tr7beans.blogspot.com/</i></font id="red"></center>

[Hasbeen]

Owen, I have no knowledge of your required jetting, but had a bit of
experience with fuel pressure on 40, & 45 DCOEs.

We had 40s on the Cosworth 105E 1100 Ford F2 engines, [107 BHP aprox
at 8000]& 45s on the 1500 Cosworth twin cam Fords [155 BHP aprox at
8000] in the AN forumla 1.5.

The 40s on the 1100s were not too senensitive, although they would
sometimes flood, but the 45s would not handle any more than 2PSI on
the twin cams. No problem under power, but, as soon as you started
braking, petrol would run out of the ram tubes.

I normally used to brake all the way into a corner in top, then go
straight back to the gear I wanted, just before turning in. At
somewhere like the hairpin, [Creek] at Warwick Farm, where you had
to knock off around 100 MPH, You had to go back through the gears,
keeping the revs above 5000, or the thing would wet out when you
tried to rev it to change back to second.

Trying to get a dog box back into gear, with a dead engine, at
50+mph is a very noisy, [& gear destroying] business. Having to wait
between 1 & 3 seconds, for a coughing, & spluttering engine to clear
itself, when you need power, NOW, is character building, to say the
least.

Some mechanics wanted higher fuel pressure, as they were frightened
of petrol running low in the float chamber, leaning the mixture, &
melting a piston. It did not happen if the thing was tuned properly .

2 PSI on 45DCOEs will run 160+ BHP, from a Cosworth 115E twin cam,
or anything else I should imagine, without any problems.

Hasbeen

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
... Filter King pressure regulator between the fuel pump and carburettors (it’s a Nr.3 which works in the range between 0.2-0.3 bar) <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
This corresponds with 2.50 to 4.20 psi

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
... I use a Facet Silver Top fuel pump, which delivers between 0.35-0.45 bar<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
This corresponds with 5.00 to 6.53 psi


<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC</font id="blue">
<font color="red">http://tr7beans.blogspot.com/</i></font id="red"></center>

[omichaelshar]

Thanks Beans for the data.