Interesting Weber jetting

[ENTDOC]

Well , I put the 40mm chokes in today and the car runs really well. I see no downside to them. The low speed manners are unchanged and the high speed performance is unbelievable. I really think 42's would be ok. I have not changed any jetting yet so after I hook up the LM-1 I will make a few changes most likely. I definitly am getting less black smoke and the plugs are not as sooty so far. If you think about it this all makes sense. How can the same chokes that typically are run on 302 cars possibly big enough for a 427(in my case 454)? I think Stefan has hit on something. Now if I could come up with a better emulsion tube.

[Eljaro]

Hello Chuck,

I made the F14 emulsion tube myself, because I could not find any.
I used a F7 tube, drilled the inside diameter to 3.5mm (it is 3.0 now) and made myself a sleeve with an interior diameter of 7.5mm and an exterior diameter of 8.2mm, length 12 to 15mm.
I used brass. You have to drill on a lathe first to 7mm, then to 7.5 to make the hole as exact as possible.
Then you turn the exterior diameter to 8.2.
Do not remove the burr for now from the edges as this will help to slip the sleeve tightly over the F7 tube.
Click image for larger version Name: F14.jpg Views: 40 Size: 18.5 KB ID: 12161
I include a picture of how this looks like. http://www.clubcobra.com/forums/atta...1&d=1166659604
You have to drill four more holes in the top row (it has only four now) to make a total of 8.
These are the tubes I have in my car right now and they work very well.
Good luck, and let me know how they work out for you.

I am glad to hear that you noticed the improvement with the 40mm chokes. No try to get the transition sorted out and you will experience the real weber feeling.
42 mm chokes may work well too. Just a matter of trying it out.
Stefan

[ENTDOC]

Stefan, do you think a F16 tube is similiar enough to a F14 to yield good results? They are readily available. If not, what other tube would you suggest? thanks; chuck

[Eljaro]

ENTDOC
The F16 tube is common usage and will not lean your low end. You will still have too rich a transition.
The higher the holes on the emulsion tube the leaner the low end gets, which is what you want to achieve. The F7 tube commonly used is for a rich transition and the main problem in that area. That is why you have the black sparkplugs and that is the reason for the stumble: too much gasoline.
I simulated the F2,F3,F14 and F15 tubes which are all supposed to be for a leaner low end.I used several different sleeves with variable holes and the best results were achieved with the F14 tubes. This of course in combination with smaller air correctors i.e. 120.

I would like to see someone trying this out (in combination with larger chokes on a BB)and posting his results. This could come confirm my findings and make weber tuning less misterious for everybody.

[ENTDOC]

so theoretically the F16 should be better than my F7,right? I do not think I am going to be able to come up with any F14 tubes and have no way to make them.

[Eljaro]

yes, the F16 tube will be better than the F7.

[BERNIE]

Originally Posted by Eljaro

Hello Chuck,

I made the F14 emulsion tube myself, because I could not find any.
I used a F7 tube, drilled the inside diameter to 3.5mm (it is 3.0 now) and made myself a sleeve with an interior diameter of 7.5mm and an exterior diameter of 8.2mm, length 12 to 15mm.
I used brass. You have to drill on a lathe first to 7mm, then to 7.5 to make the hole as exact as possible.
Then you turn the exterior diameter to 8.2.
Do not remove the burr for now from the edges as this will help to slip the sleeve tightly over the F7 tube.
Click image for larger version Name: F14.jpg Views: 40 Size: 18.5 KB ID: 12161
I include a picture of how this looks like. http://www.clubcobra.com/forums/atta...1&d=1166659604
You have to drill four more holes in the top row (it has only four now) to make a total of 8.
These are the tubes I have in my car right now and they work very well.
Good luck, and let me know how they work out for you.

I am glad to hear that you noticed the improvement with the 40mm chokes. No try to get the transition sorted out and you will experience the real weber feeling.
42 mm chokes may work well too. Just a matter of trying it out.
Stefan

Eljaro,
Find F14 from pierce manifolds (expensive,but!!!)
Bernie

[Eljaro]

get them !
You can allways drill more holes and make some other tube out of it.
They worked best.
stefan

[ENTDOC]

I did not see F14 for IDA carbs on their site

[BERNIE]

True but they have in stock,received a week ago,
Regards,
Bernie

[ENTDOC]

I found them Bernie, 45 bucks each,ouch