DCOE setup help request

[Marsu]

I've recently fitted a pair of DCOE 45 that I bought off ebay. I really need some advice to get this setup properly. At present it is not really driveable using a moderate to mild throttle. It does work ok with more open throttle application - but this is not practicable.

BACKGROUND:
The carbs came attached to a fabricated steel manifold from another Wedge with a blown (read detonated) Sprint engine.


I gave the setup a thorough clean and fitted new carb gaskets. At the same time I recorded the following details regarding the carbs:
- Model 45DCOE13 (Type 5H - non-emissions)
- Main venturi: 34
- Aux venturi: 4.5
- Emulsion tube: F15
- Main jet: 135
- Air correction jet: 175
- Idle jet: 50F9

I haven't measured the float level as I am not quite sure how to do that. I'm still running the old mechanical fuel pump but have a gauge inline between the two carbs and it reads between 3.5 and 5.0 psi depending upon revs, which seems in the ball park and never falls below the former value. (I've since removed this gauge, as evidenced in the pic above.)

The head inlet ports have some mild (amateur) porting and I noticed that they were covered by some carbon on their lower sides during the 20,000k they were running the old 1.75" SUs with the cam. The cam is supposedly an uprated unit with 70/40 profile but I have not measured it and lift is unknown.

A new inlet manifold gasket was fitted using standard gasket adhesive and a silicon bead around the head/thermostat water transfer port. I am confident there are no vacuum leaks (nor water) between head/manifold and manifold/carbs (new O ring gaskets fitted).

SITREP:
When it first fired up the idle was much rougher than I've heard before but on the test drive it patently had more grunt in the top end. But I now want it more balanced.

Following are items I would welcome some suggestions on:
- No 2 piston (rear barrel on front carb) seems problematic:
- it leaks fuel back out the ram tube (not a lot, but none of the others do)
- the idle speed screw is a lot further in on this barrel than the other three
- Adjusting the idle mixture screws readically upsets the carb balance set by the idle speed screws

Simply, I feel screwed and out of my comfort zone!

[Troy ODoherty]

Webers respond to logic patience and an eye for deail better than most things mechanical.
To check that there are no air leaks get a can of CRC clean a carb and spray around the gasket areas on the manifold. any change in idle speed will indicate an air leak.
The chokes are about right. I would think that the emolsion tubes are possibley wrong but I will look them up later and let you know what I am using. I have twin 45s on a sprint and an 8 valve as well as the quad 48s on the V8.
You need to set all of the idle screws to the same setting. wind them in untill they gently bottom then screw them out about 2.5turns if they are old italian Webers. Double this if they are the newer spanish version.
Check that the carbs are balanced. You can use a piece of hose and listen to ensure that they are using the same volume of air. the hiss will be the same. If you have a balancer use that ( try EBAY)as they make life very easy. If your eyes are still young enough you can take the progression port covers off and look down and see that the throttle plate is moving past the hole at the same time. Dont loose the plug as they are hard to replace. It is the brass plug on top of the chokes in line with the retaining nut.

Do a search on the web on how to tune them as there are a couple of good sites out there. If you can get a copy of the genuine Weber book it will all become very simple.

The golden rule is if you turn one screw then you must turn all the others the same amount or your life with Webers will be a miserey.

I will find my setting and post them for you.

Cheers Troy

[PeterTR7V8]

They look very nice. I found these settings...

Conversion Kit number: K161
Main Venturi: 30
Aux. Venturi: 4.5
Main Jet: 125
Emulsion tube: F9
Air Corrector Jet: 155
Idle Jet: 55F8
Acc. Pump Jet: 45
Pump Ex. Valve: 45

on this website http://www.poustusa.com/weber_carb_page ... _weber.htm

Unfortunately these are for a DCOE 40.



The map: http://tinyurl.com/wedgemap . The blog: http://www.forum.triumphtr7.com/topic.asp?TOPIC_ID=8548

[jeffremj]

Triumphtune have 3 settings for the 45DCOE on a 16V:

Aux venturi: 4.5 for all settings
Emulsion tube: F16 for all settings
Pump jet: 50 for all settings
Choke: 34,34,36
Main jet: 130,125,160
Air jet 200,195,250
Idle jet: 45F9,50F9,55F9

[DNK]

Mars, if you get tired of that set up,

http://seattle.craigslist.org/see/pts/2029468708.html

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Marsu</i>

... a pair of DCOE 45 ... cam is supposedly an uprated unit with 70/40 profile <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
In that case your cam comes very close to the group 2 cam I have in my car. Do a search in the Sprint section for my set up.

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jeffremj</i>

Triumphtune have 3 settings for the 45DCOE on a 16V:
Choke: 34 for all settings ... <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Sorry, have to correct you there, they have two settings using 34 and one using 36 chokes [;)]

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[jeffremj]

Corrected.

[Beans]

Thought this one was in the Sprint forum, but it wasn't ...
<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Beans</i>

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).<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Marsu]

Thanks all for suggestions so far. I was tired and frustrated yesterday so didn't explain things as well as I should.

Yesterday I first attempted to synch the carbs using a meter and found that to get a reasonable balance I had to tighten No 2 cylinder idle speed screw much more than the other 3. The screw appears to be about 1/3rd the height of the others.

Following some instructions I found on the web I then attempted to get a "best lean idle":
- Let the engine warm to temp and then shut down
- Tighten the mixture screws until fully home
- Back them out one 1/2 turn
- Restart engine and tighten mixture screws 1/8 turn at a time, waiting 5-10 seconds after adjusting each screw before moving to the next. After 3 passes of all four screws the idle started to fall so I backed off a 1/4 of a turn and left them there.

This produced a much smoother idle and, judged by the exhausat appearance and smell, was much leaner.

But the balance was now massively out so I attempted to synch again. To get balance the screw on No 1 was backed so far out it dropped out when I took the car for a short test drive [B)]

The car is really undrivable on anything less than 1/2 throttle and much worse than when prior to making the adjustments. [V]

I've now come across other instructions that give different info regarding setting the mixture.

What worries me most is the discrepancy between the idle speed screw on No 2. Could this be indicating a twisted shaft? This throat is now leaking fuel back out the ram tube. Not a lot, but a steady drip every few seconds. None of the others do.

---
I'm going to have another go this morning and will check for vacuum leaks.

I came across the following [url="http://www.redlineweber.com/html/Tech/dcoe_adjustment_layout_typical_i.htm"]instructions[/url]. They mention setting air by-pass screws to in closed position. Comments welcome.

[Troy ODoherty]

Hi Marsu
How did you get on with it today?

Just to clarify a couple of thing
Try this

1 Back the idle speed screws for both carbies out untill just clear of there tangs.

2 Check that the throtlle plates are in the same place on both carbies by looking down the progression port holes under the brass plugs. This will show a twisted shaft if you have one. Not very common.

3 zero and reset the idle mixtuer screws so they are all out the same number of turns.

4 start the engine, if it wont idle adjust only the idle speed screw on the front carby

5 Using the balance screw, the one near the twin return springs, to adjust the balance between the front and rear carby.

6 Adjust the idle mixtures as you did yesterday

It should now idle reasonably well
The idle mixture screw does not effect the balance between the carbs.
The float levels need to be correct as they have a bearing on the operation of the emolsion tubes. I Doubt that the F15 are the correct tubes for this application.Both of my 4 cylinders are using F7s. The tubes are numbered in the order that they were developed in. IE they are not numbered rich to lean or anything usefull.

http://www.centerlinealfa.com/tips/imag ... r_info.pdf

This will tell you how to set the float levels

Dont worry about the idle by pass screws as your carbies dont have them.[:)]

If you check all the cylinders with the balance meter and they are out in the same carby you may have a twisted shaft, air leak or a problem in a cylinder.
Once you have done all this you can check the idle jet setting by a simple test that I will describe if need be.The drivability is controlled by the emolsion tubes. They control when the engine progresses from the idle circuit to the mains.

Let us know how you get on and if possible we will help with the next step..
http://www.weberperformance.com.au/ If you need parts try Daniel. He is the cheapest I have found and offers great service. He sells the genuine Weber manual. Dont bother with the other book he sells as it is well beyond most backyard tuners.[:D]

Cheers Troy

[bmcecosse]

Since the chokes are only 34 mm = 1.34" and your original carbs were 1.75", it's a mystery to me how you think the car will run better on these carbs ! And don't just say 'there is one per cylinder' because each cylinder breathes independently anyway - only ONE cylinder is pulling through a carb at any one time. I believe you should be looking at much larger chokes if you really want power - but in fact - the twin 1.75" SUs are well capable of handling up to 40 BHP per cylinder anyway. The carbs are not the limiting power factor on the TR7 engine. The fuel consumption on the Webers will be horrific!

[Troy ODoherty]

Largely it comes back to what you can get serviced. The CD carbys have an average reputation in Aus. The SU are OK to deal with and the Japanese Hitachi's slightly better, BUT the Strombergs are bloody awefull to deal with on a good day.
The Weber is a very easy thing to get info and parts for out here and nothing sounds quite like webers on song. They are very tunable and produce great power and driveability as well as reasonable fuel consumption when set up properly and driven resposibly.

There are also good reason why the works cars used them.

There is all sorts of theory on why single choke per cylinder is better, but the proof is in the many teams that have used them in all types of serious compitition all over the world.[:D]

Cheers Troy

[bmcecosse]

Ahh - for out and out best power on a highly tuned engine - YES! And they won't be running miserable 34mm chokes. You can get 42mm chokes for a 45 DCOE......
I agree about CDs - throw them away! The SUs can be usefully improved á la Vizard!!

[Marsu]

Hi Troy,

Unfortunately I wasn't able to make further progress as my intermitent "no spark" condition returned. In disgust, I succumbed to a mate's encouragement to give up and go and drink beer instead.

Logically, I have to solve the eratic spark before attempting anymore carb tuning. I thought I had it sorted - well, it had gone away. I'll be fitting the spare dissy with new points and condensor and a new ballast resistor, these being the only elements of the ignition that I have not changed.

Thanks again for the additional info, particularly using the balance screw near the twin return springs. I had thought this screw was to adjust idle speed after balancing each carb using the speed screws. Your comment caused me to look again and realise my approach was wrong.

In future I'll only adjust the idle speed screw on the front carby and then use the balance screw. I assume that once set I should then tighten the rear carb idle speed screw until it just touches the tang?

As suggested, I'll check the throttle plates and hope this will pacify my concern regarding twisted shaft. I'll also check the float levels and adjust if necessary.

The carbs came with spare 185 main jets and F16 emulsion tubes but the guy I bought the setup off couldn't tell me if this was richer or leaner so I have stayed with the orig setup as it was from a mildly tuned Sprint engine.

I'll update this post once I make progress, but probably not before next weekend.