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Discussion Starter #1
I'm running a pair of DCOE40 44/45 carbs on my 1975 GT Junior / GTV hybrid.

It's running a stock 2 litre which a previous owner swapped in for the original 1600. He also appears to have carried the carbs over from the 1600 unchanged. I have made them more like the DCOE40 spec used on the 2 litre. I have changed the chokes from 30 to 32, mains from 117 to 135. I'm currently using 55F8 idle jets. F16 emulsion tubes.
The carbs have brass floats, fine threaded idle screws and air by-pass screws *emissions carbs". I'm using a 123 distributor.

Would 8.5mm be the best float height?

My carb book (Des Hammill) suggests a range of 5.5mm to 7.5mm. My Brooklands manual suggests 8.5mm except for the GT Junior 1600, which it suggests should be 7mm

My car is running too rich (black plugs), when I try to lean it out by switching to 50F8 and/or winding the idle screws in from about 5 turns out, I get stumbles.

Thanks in advance,
 

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I'm running a pair of DCOE40 44/45 carbs on my 1975 GT Junior / GTV hybrid.

It's running a stock 2 litre which a previous owner swapped in for the original 1600. He also appears to have carried the carbs over from the 1600 unchanged. I have made them more like the DCOE40 spec used on the 2 litre. I have changed the chokes from 30 to 32, mains from 117 to 135. I'm currently using 55F8 idle jets. F16 emulsion tubes.
The carbs have brass floats, fine threaded idle screws and air by-pass screws *emissions carbs". I'm using a 123 distributor.

Would 8.5mm be the best float height?

My carb book (Des Hammill) suggests a range of 5.5mm to 7.5mm. My Brooklands manual suggests 8.5mm except for the GT Junior 1600, which it suggests should be 7mm

My car is running too rich (black plugs), when I try to lean it out by switching to 50F8 and/or winding the idle screws in from about 5 turns out, I get stumbles.

Thanks in advance,
According to my Haynes Weber book #393 it specifically says for 40 DCOE 44/45 ...Closed position 7 mm Open position 14 mm ....leaving a stroke of 7mm
 

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I also have the 44/45 on my 2000GTV
I also have issues to get them to work properly.
Maybe the progression holes just don’t work for the 2000?

Anybody that successfully use this carbs on the 2000?
 

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The most under-rated part of rebuilding a DCOE is to make sure the internal channels are clear. No amount of soaking and cleaning will clear these unless you drill out the lead plugs and ream them out with a tiny drill bit of the size of the channel using only your forefinger and thumb as the reaming device. The bottom horizontal one is usually the worst offender when they get plugged because of gravity working on sediment and the carbs will NOT WORK if it is clogged.. Gordon Raymond is the go to guy in this department.
 

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The important fuel level is the one in the well. Here is how to measure it. If it is wrong you then adjust the float tabs and some trial and error may be involved.
 

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Discussion Starter #6
The important fuel level is the one in the well. Here is how to measure it. If it is wrong you then adjust the float tabs and some trial and error may be involved.
Thanks, I will make a measurement
 

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Discussion Starter #7
According to my Haynes Weber book #393 it specifically says for 40 DCOE 44/45 ...Closed position 7 mm Open position 14 mm ....leaving a stroke of 7mm
Yes, but that is for the 1600 Junior, which is the only factory application for this carb. Would/Should it be the same if used on a 2 litre ?
 

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The application does not usually affect the required fuel height. I understand that with 45DCOE's some motors want 1 mm more or 1 mm less.
 

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So, when making float adjustments, do you measure to the float seam, or the shoulder of the floats... Brass floats, of course.... ? Or is the difference insignificant?
 

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Discussion Starter #10
So, when making float adjustments, do you measure to the float seam, or the shoulder of the floats... Brass floats, of course.... ? Or is the difference insignificant?
I have a float gauge with cut outs which prevents it including the seem when you take a measurement. It's an 8mm & 9mm one, so If I'm going to 7mm, I will need to improvise.
 

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Ah, shoulders/flats it is then. I actually think I have seen one of those, now I think further.
Thank you.
 

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Discussion Starter #13
Dropping the float height measurement from 8.5 to 7mm seems to help with the stumble. Perhaps now I can switch to from 55f8 to 50f8 idle jets / and/or wind in the fuel screws....
 

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I had a minor stumble when taking off in my duetto 1600 a while back.
Weber 40 DCOE 27s with 120 mains, 35 accelerator jets, 50F11 idle jets.
All factory spec.
My parts bin contained an unused brass float.
I pulled the floats from the car and aligned them according to the parts bin float.
The ones in use were only slightly off but a little tweak to the tabs made a huge difference.
Fuel level was a little too low, enough to make a problem when the accelerator jets came in to play.
Made the adjustment, reinstalled them and no more stumbling.
Previous owner's mechanic tinkered with them and also had the wrong jets in them initially.
My understanding is that as long as you are certain that you have a matched pair of Webers, you should be able to get good results.
If they're not identical internal castings and drillings, jets, air correctors, venturi, etc, you'll chase endless problems.
I hope this will help.
 

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I had a minor stumble when taking off in my duetto 1600 a while back.
Weber 40 DCOE 27s with 120 mains, 35 accelerator jets, 50F11 idle jets.
All factory spec.
My parts bin contained an unused brass float.
I pulled the floats from the car and aligned them according to the parts bin float.
The ones in use were only slightly off but a little tweak to the tabs made a huge difference.
Fuel level was a little too low, enough to make a problem when the accelerator jets came in to play.
Made the adjustment, reinstalled them and no more stumbling.
Previous owner's mechanic tinkered with them and also had the wrong jets in them initially.
My understanding is that as long as you are certain that you have a matched pair of Webers, you should be able to get good results.
If they're not identical internal castings and drillings, jets, air correctors, venturi, etc, you'll chase endless problems.
I hope this will help.
The ball on the float tab can wear a dimple on the tab ...It is enough to throw the float level off
 

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On topic of "FLOAT HEIGHT": when you’re adjusting float height do you have to make any corrections for new vs. old gasoline (unleaded vs. heavier leaded) when youre looking at the original float specs...??
1631666

....if modern gas is lighter (= less dense) but you want the level to be the same as it used to be in the float bowl (as originally spec'd), don’t you need to increase A (by say 1mm) but keep B the same (cause you want the range of motion the same regardless of the density of the fuel)?? Because the float (whose weight has not changed) needs to displace more fuel to rise to the same place...??? Or have I got it the wrong way around :)
thanks
ps. dont mean to hijack the thread but thought it was relevant to this discussion.
 

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...which I might add, is why Alfaparticle's technique of measuring it, is ultimately the best way to understand if its really working......
 
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