Weber jetting for 20S engine
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97 Posts
jetting the 45 DCOE
Well...I've got the same side-draft carb on my 2L Opel.
I have a larger cam and ported heads with lots of air flow.
I tried the recomended jet sizes for a stock engine of that size but it would run at an idel and not when you open the throttle...too lean, probably because my engine has alot more air-flow than stock.
With an O2 analyzer reading of 1 percent O2 in the exhaust, I finally ended up with 185 jets in an f8 tube...ya, it sounds big, but you can see for your self... My car runs great !
p.s. The DCOE series I've found has a slight flat spot during acceleration...Just the nature of the beast.
Well...I've got the same side-draft carb on my 2L Opel.
I have a larger cam and ported heads with lots of air flow.
I tried the recomended jet sizes for a stock engine of that size but it would run at an idel and not when you open the throttle...too lean, probably because my engine has alot more air-flow than stock.
With an O2 analyzer reading of 1 percent O2 in the exhaust, I finally ended up with 185 jets in an f8 tube...ya, it sounds big, but you can see for your self... My car runs great !
p.s. The DCOE series I've found has a slight flat spot during acceleration...Just the nature of the beast.
Joined
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5,299 Posts
Transition terminology
That's why the term idle jets and idle air bleeds are such a misnomer . . . they only cover HALF their functionality! And why do you think Weber offers a range of DCOE40 and 45 "types" and it's always recommended that you use the same "type" on an engine? . . . because they were originally designed for engines of a specific displacement and breathing efficiency.
I think there's a small misinterpretation of terminology here . . . you CAN, in fact, adjust idle/transition MIXTURE (idle jets and air bleeds) and idle mixture VOLUME by the idle adjustment needle. But you CAN'T adjust transition mixture VOLUME, as it's controlled by a series of fixed orifices just above the throttle plates. The ONLY way to alter transition mixture VOLUME is to enlarge these orifices (holes).Crusher said:You're right, there is no means of adjusting the transition mixture on the DCOE.
I've been sort of leary of drilling on my carb
Kummel - I hope we've added some insight to your carb project.
Steve
That's why the term idle jets and idle air bleeds are such a misnomer . . . they only cover HALF their functionality! And why do you think Weber offers a range of DCOE40 and 45 "types" and it's always recommended that you use the same "type" on an engine? . . . because they were originally designed for engines of a specific displacement and breathing efficiency.
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5,564 Posts
For an "everyday" car the standard cam will be OK as it makes peak power above 5,000 rpm and the DOCEs' will allow better power anyway.
Just keep the venturis down in size (30 to 34 mm) for better low end response. This may restrict your hi-rev power but most everyday drives operate at the low rev range most of the time. So just "tune" those 45s' to the rev range most often used.
Just keep the venturis down in size (30 to 34 mm) for better low end response. This may restrict your hi-rev power but most everyday drives operate at the low rev range most of the time. So just "tune" those 45s' to the rev range most often used.
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15,257 Posts
Jim is absolutely right, the choke (venturi) size is very important. You can use the 45 DCOE on a standard 2.0 but you should run a small venturi for good torque and mixture signal. I would probably use 32 mm. If you have long air horns (trumpets) then that would be better too for road use.
Make sure that your exhaust pipe diameter is not too large as well. I would not go larger than 2.25" (58 mm), but you may be better off with 2" (51 mm).
Bob
Make sure that your exhaust pipe diameter is not too large as well. I would not go larger than 2.25" (58 mm), but you may be better off with 2" (51 mm).
Bob
what emulsion tube should i use?
I m planning to order some stuff from finland and i want to get everything.
I have fuel and air jets, im planning to go for 34mm chokes. because im planning
to work with head also. Today i got a new clutch, you can also use 2 liter kadett GSI clutch and senator 2,5 disk. it has 6 polts instead of original 4 polts
I m planning to order some stuff from finland and i want to get everything.
I have fuel and air jets, im planning to go for 34mm chokes. because im planning
to work with head also. Today i got a new clutch, you can also use 2 liter kadett GSI clutch and senator 2,5 disk. it has 6 polts instead of original 4 polts
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