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Chris Chow
Guest
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 Posted: Sat Dec 13, 2003 11:18 am Post subject: Carburettor Setting |
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| Can someone advise me to some links which I can get more info? I have change most of my jettings and realised that the idle jets are not within idle adjustments. I think I need to upsize the idle jet. Any suggestions? Its' idling a little too high now. This happened only after cam change. If so, where can I buy the dellortto's jets? |
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Guest
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| Posted: Fri Dec 19, 2003 2:15 pm Post subject: |
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| a 55 to 60 idle jet should do the job, i had those in my 45 webers (p4 16V). but the air valves are also crucial. |
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Serpent33
Alfa Sprint
Joined: 06 May 2003
Posts: 210
Location: Singapore
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| Posted: Wed Mar 31, 2004 2:19 pm Post subject: |
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| Anonymous wrote: |
| a 55 to 60 idle jet should do the job, i had those in my 45 webers (p4 16V). but the air valves are also crucial. |
So wht air jets are you using? I am using the smallest one tI can find. Forgot the reading.
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Each time I speed I say, "Dear lord, make me fast and accurate..." |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Tue Jun 29, 2004 2:44 pm Post subject: |
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| Tell me the size of the engine and max. power revs, and I'll calculate the jets for the car. |
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Guest
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| Posted: Wed Jun 30, 2004 7:05 am Post subject: |
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| neo wrote: |
| Tell me the size of the engine and max. power revs, and I'll calculate the jets for the car. |
about 1710cc. Intake port enlarged 2-3 mm, standard cams but considering fast road profile. Currently I'm using stadard 1.7 QV jets. After checking plug at high speeds it seems fine. Upped size of main jet to about 150. Anyway just crashed the 33. Someone came from behind me and hit me at a very high speed. It will be a while more before I talk about tuning the car. Thanks for your help. |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Wed Jun 30, 2004 3:34 pm Post subject: |
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| Anonymous wrote: |
| neo wrote: |
| Tell me the size of the engine and max. power revs, and I'll calculate the jets for the car. |
about 1710cc. Intake port enlarged 2-3 mm, standard cams but considering fast road profile. Currently I'm using stadard 1.7 QV jets. After checking plug at high speeds it seems fine. Upped size of main jet to about 150. Anyway just crashed the 33. Someone came from behind me and hit me at a very high speed. It will be a while more before I talk about tuning the car. Thanks for your help. |
if your peak power is at 6500 rpm then you should use
Weber Carb Settings
Choke size 36
Main jets 145
Emulsion tubes F9/F16
Air correctors 180
Idle jets 45f9 (Weak F8/F11/F2 Rich F6)
Pump Jets 35/40
Aux Venturis 4.5
if your peak power is at 7000 rpm then you should use
Weber Carb Settings
Choke size 38
Main jets 155
Emulsion tubes F9/F16
Air correctors 190
Idle jets 45f9 (Weak F8/F11/F2 Rich F6)
Pump Jets 35/40
Aux Venturis 4.5
You'll probably wont be able to find the choke so big. I think that the biggest one is 32 for the 40 carb. You'll have to enlarge it. I've mange to overbore the choke to a 37 mm and still kept the geometry of the venturi. |
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Serpent33
Alfa Sprint
Joined: 06 May 2003
Posts: 210
Location: Singapore
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| Posted: Mon Oct 11, 2004 12:13 pm Post subject: |
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You'll probably wont be able to find the choke so big. I think that the biggest one is 32 for the 40 carb. You'll have to enlarge it. I've mange to overbore the choke to a 37 mm and still kept the geometry of the venturi.[/quote]
Hi Neo. My car is back on the road now. Does such a big choke size affect drivability? And if inlet port is not enlarged, is the bigger choke really efficient?
_________________
Each time I speed I say, "Dear lord, make me fast and accurate..." |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Mon Oct 11, 2004 1:50 pm Post subject: |
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| Serpent33 wrote: |
| You'll probably wont be able to find the choke so big. I think that the biggest one is 32 for the 40 carb. You'll have to enlarge it. I've mange to overbore the choke to a 37 mm and still kept the geometry of the venturi. |
Hi Neo. My car is back on the road now. Does such a big choke size affect drivability? And if inlet port is not enlarged, is the bigger choke really efficient?[/quote]
Hi!
It doesn't affect drivability that much if the engine is well tuned. Maybe you'll lose some engine response between 2000 and 3000 rpm, but after that you will just have improvments.
Bigger choke is efficinet but you'll get a bit more power if the inlet port is enlarged.
If you use a smaller choke be sure to use smaller main jets or larger main air correctors because you'll have to rich mixture because the smaller the choke is the bigger pressure drop it creates and more fuel comes out. |
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Guest
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| Posted: Wed Oct 13, 2004 1:59 pm Post subject: |
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| Just remembered reading from some books max effective choke size for 40 carbs is 36. Any bigger is better off with 45 carbs |
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