Webers 45 vs 40 dcoe

[Hamish]

Hi folks 

my Spanish 45dcoe twin carbs 36mm chokes have never seemed to be reliable settings wise tending to always revert to rich. 
the idle mixture screws are also not matching ( number of turns) in any way but set on RR 

I do have a set of Italian 40dcoe with 36mm chokes

do you think it’s worth swapping them ?

will there be a characteristic change? The car is 2288cc

should I just swap the various jets to get a base line. 
 

then RR it for next season. 
advice thoughts welcome..
 

[Escadrille Ecosse]

Hamish. The key bit in the Weber is the choke size. A 45 will accept a larger choke than a 40 if that is what is required, especially if you want to go further with the tuning.

But since you are on 36 chokes and probably near the tuning limit then my call would be to go for the 40s and as a basic setup use the same jets and venturis as the 45s which should be enough to get it running.

Nothing is guaranteed but the Italian carbs are likely to be better than the Spanish ones. I have original Italian 40s on the Spitfire (30 chokes) and no issues with holding tune.

This is a useful article on the subject

http://www.s262612653.websitehome.co.uk/DVAndrews/webers.htm

Edited November 3 by Escadrille Ecosse