46mm webber questions

[Eagledriver]

I bought some webber carbs that were supposed to be 46mm carbs. They are 40 IDT's and have had the bottom modified to enlarge them to 46mm. The work looks good but I have some questions.

1) Do real 46mm webbers share the housing with 40mm and are just bored out?

2) Do real 46mm webbers have different transition holes than 40mm? Mine has 4 holes instead of 3 and they are larger than on a set of 40's.

3) Do real 46mm webbers have different idle mixture screws? Mine stick out into the bores because the bases have been bored out.

4) Do I have any hope of making these run right?

-Andy

[Henry Schmidt]

I don't have the answers to your questions except to say that if they were modified correctly they should work very well. We did this modification many times in the past with very good success.
Many vintage racers are running this kind of modification because 46 mm Webers are illegal in some clubs and the bored out 40s look stock.
Cheating? imagine that.

[914/6]

Harry's been doing them for years.
http://www.biekerengineering.com/

[addictionMS]

1) Do real 46mm webbers share the housing with 40mm and are just bored out?

2) Do real 46mm webbers have different transition holes than 40mm? Mine has 4 holes instead of 3 and they are larger than on a set of 40's.

3) Do real 46mm webbers have different idle mixture screws? Mine stick out into the bores because the bases have been bored out.

4) Do I have any hope of making these run right?

1)no, 46mm are a different casting.

2) my 46mms have three, sounds like yours were tuned, it is not unheard of to have additional holes drilled in them to help with the transition

3)nope, same screws, they do not stick out, because the casting is different.

4)I see no reason why not, but it will be tougher because you will not be able to count on any of the standard settings, but they should be good starting points.

jim