Weber 48 IDA - Show me your linkages

[chuck smith]

not an original car?

 

[Randy V]

While it's not topical (Weber IDA linkage) - it is a move in the right direction. Please start a thread in the Build Logs section to show us more.

http://www.gt40s.com/forum/gt40-build-logs/

Thanks.

 

[Charlie Farley]

fav,

It wouldnt work with Doc's webers.
So why waste all these people's time posting those photos.
Or have you missed the point?

Oh, and if you are still in the belligerent frame of mind you so ably
demonstrated in all your posts, may i make a suggestion ?

Take a budget airlines flight to Kandahar and go take it out on the Taliban.
They will appreciate the opportunity.

 

[Johan]

I can see it now, driving along and there is a big "whummmp" noise, and a big plastic bubble starts growing out the exhaust.

 

[Ron Earp]

It is obvious that you have never seen a Holman Moody MKIIB.

favgt40, you've been a member for the forum for quite some time. Your profile shows that you live in NC, so one must assume that you are part of H&M in some way.

Maybe you could provide a bit of information about yourself to the forum members and let people get to know you, instead of one sentence inflammatory replies. I'm sure the membership would appreciate it and I think you'd enjoy the forum more as a result.

Ron

 

[Tim]

Ron, lynn knows who I am. I would be glad to have you come to the house some time. Send me an email with your phone number, and I will return your call. Thanks.

 

[Gregg]

Tim, are the polycarbonate carb enclosures available for purchase?

 

[John Fitzpatrick]

I found some very helpful info and diagrams on linkage geometry and set-up directly applicable to Andy's configuration here: pg 23 .

 

[Doc Watson]

Just about to see what effect the placement of the central bar has on throttle opening. The bar is original so the only 'play' in the assembly is the side shift of the bar (moving the bar assembly left or right a little) and of course rotating the shaft. Two unknows is still one to many.

Its more fun than getting 40 year old rust off a Smiths heater box.

Will post when done.

Andy

Addendum....
Before launching into some trig to solve this problem would the best solution be to balance the carbs using an airflow meter? I know that an initial set-up is required but individual balancing would be the final 'tune' wouldnt it?

 

[Steve C]

Andy,

I agree that airflow after initial set up is way to go but as I'm sure you know linkage needs to be able to equally open each carb through its entire travel, and that should be insured in linkage design.

Steve

 

[Randy V]

Man I hope this works and is some sort of help to you Andy - Spent the last couple hours diddling with drivers for the scanner to snatch this for you..

I know that the manifold is of a different design but the basic premise and geometry may be of some help..

 

[John P]

Speaking of Webers..

I've seen adapters that Turn an IDA 180º to the normal direction. The photos I saw had both the fuel lines between the carbs, instead of the outside. Is there any advantage to this? This was on a Cobra. John

 

[john]

Gotcha beat Johan!!

 

[John Fitzpatrick]

Andy-
I don't know how you're planning to hook up your links, but looking at your drawing, if the cable is to the right side and each carb is connected by a separate link to the T, it seems like the carb on the left would open slowly in the beginning then more rapidly, while the one on the right would open very quickly with just a little cable pull. If you tie the left and right carbs together with a crossbar and link the T to the left carb, you'd get the first case but the with the two carbs synchronized; link to the right, second case.

 

[Johan]

Gotcha beat Johan!!

Cool !

 

[Doc Watson]

Starting condition, Webers throttles both at 39 degrees.....

 

[Doc Watson]

The linkage animates a few cycles, and the data is given...

a1 is the left throttle angle
a3 is the right throttle angle

min and max are the respective differences between the two throttle levers over a whole cycle, in this run the worst case is a difference of -2.92 degrees.

The 'graph' ahhemmm..... shows the difference in throttle angle over 2 and a bit cycles, note the cycle starts with both throttles fully closed.

By changing the position of the shaft at x3,y3 (moving horizontally only) and rotation the shaft (i.e. moving x4,y4 and x7,y7) you can optimise the geometry for a minimum difference in throttle angle.

Im still optimising........

 

[Doc Watson]

By increasing the weber linkage from 30mm to 40mm the maximum difference between the two carb levers is 1.6 degrees at 1/2 throttle, note minimal change at zero and full throttle.

How close is close enough??????

Andy

 

[Doc Watson]

Have I killed this thread with to much information?

Would this program be useful to anybody else?

Do I need to get out more?

 

[Randy V]

I think that now the thread is more focused on linkages - it's all valuable information. No one wants to drive a high powered car with a throttle that works like a light-switch!

I'm still hoping to see more on IDA linkages - pro's and con's of the various linkage types etc..

More pictures from people would be really good. Particularly side view close-ups of the center pull design linkages.