15 replies to this topic

[sovenmini]

hi will a weber dcoe 40 run fine on a 1380 engine or will it be too small.
at the moment it was a hif44 on it

[WiredbyWilson]

Yes, it will be fine - i run one on a tuned 1330. You just need it to be RR'd to get the jetting right.

[bmcecosse]

Too small in my opinion! 45 would be ok, but 40 has small chokes. Best stick with the HIF44 meantime.

[WiredbyWilson]

Chokes can be changed..........

[sprintmini]

Im building a 1380 and my engine builder says a 40DCOE with the correct chokes and jets etc will be fine.
If using a 45DCOE on a 1380 then you have to use a small choke for that carb,whereas using the 40 you can get the same choke size.

[m1tch]

Im building a 1380 and my engine builder says a 40DCOE with the correct chokes and jets etc will be fine.
If using a 45DCOE on a 1380 then you have to use a small choke for that carb,whereas using the 40 you can get the same choke size.

THis is what my weber 40 has in it:

Main jets: 150
Correctors: 160
E-tube: F2

Idle jets: 50
E-tube: F8

Starter jets: 100
E-tube: F5

Pump jet: 45

Running 40mm venturis

Those are the largest venturis you can possbily fit in a 40 lol

[bmcecosse]

You can't put 40 mm chokes in a weber 40! You can - in a 45. Max 34 in a weber 40 - or specailly bore them to 36, max 40 chokes in 45 - or again - they can be specially bored to 42.

[m1tch]

You can't put 40 mm chokes in a weber 40! You can - in a 45. Max 34 in a weber 40 - or specailly bore them to 36, max 40 chokes in 45 - or again - they can be specially bored to 42.

Just measured the ID of the venturis, they are 40mm, says on the top of the weber I have:

Tipo: 40DCOE18





The ID of the edge of the venturi is 40mm, going to about 38 at the narrowest part of the venturi

Edited by m1tch, 09 July 2009 - 07:25 PM.

[Nightrain]

Im with roy on this, you can't get 38's in a 40dcoe, but it'll work fine on a 1380. Ok you won't have as much potential power as with a 45, but it will work and imho better than the SU. The size should be embossed on the chokes.

[m1tch]

Im with roy on this, you can't get 38's in a 40dcoe, but it'll work fine on a 1380. Ok you won't have as much potential power as with a 45, but it will work and imho better than the SU. The size should be embossed on the chokes.

Which part? inside or outside?

[Nightrain]

Im with roy on this, you can't get 38's in a 40dcoe, but it'll work fine on a 1380. Ok you won't have as much potential power as with a 45, but it will work and imho better than the SU. The size should be embossed on the chokes.

Which part? inside or outside?

You can just about make it out and they are 34mm, circled

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Edited by Nightrain, 09 July 2009 - 08:37 PM.

[m1tch]

Im with roy on this, you can't get 38's in a 40dcoe, but it'll work fine on a 1380. Ok you won't have as much potential power as with a 45, but it will work and imho better than the SU. The size should be embossed on the chokes.

Which part? inside or outside?

You can just about make it out and they are 34mm, circled

Where is the measurement taken from then? lol is it the smallest part of the venturi? would these be any good for a 998? lol

[Nightrain]

Yes the inside of the choke, what people don't seem to get with webers is demonstrated well in this post. The choke is actually used to accelerate the mixture, you still have 40mm worth of air going into the carb. As it reaches the choke it is speeded up, which increases the torque of the engine.
Yes it will work fine on a 998 as well.

[m1tch]

Yes the inside of the choke, what people don't seem to get with webers is demonstrated well in this post. The choke is actually used to accelerate the mixture, you still have 40mm worth of air going into the carb. As it reaches the choke it is speeded up, which increases the torque of the engine.
Yes it will work fine on a 998 as well.

Tis why they are called venturis lol tis the venturi effect, same air throught a smaller gap = increase air speed across the fuel jet hmm I might fit that to my 998 then lol, I think I might need to change the jetting a tad though!

P.S. sorry for the thread hi-jack

Is there anywhere with starting setups for jetting? I have read:

Main jet = venturi times 4
Air correction = main jet plus 50
Idle jet = 50

Can anyone post up what engine and what weber jetting they are running?

[Nightrain]

m1tch the auxiliary venturi is used to magnify the air speed over the main jet, thats what the inner tube in the choke does