[amallagh]

Again, thankyou for all the responces. A lot of the responces are contextualised in regard to road cars where mid range response dominates completely. Not surprisingly then most of the recommendations are for 40s with 34mm chokes. Although this engine will be used on the street and track, it is ultimately a race replica engine with a milder cam and peak power and characteristic is important.

Paul, I am particularly interested in your detailed response, crucially because it builds on the links I'd mentioned in my first post. Thankyou.

You mention a '2.5 liter with GE 60 cams, twin plug and 911R muffler. It made 251 HP @ 7034 RPM. The Webers were 44mm with 36mm chokes'. This is course is the most similar example so far to this engine I'm building.

You mention, '34mm for DC40 cams & 36mm for DC60 cams is what I would recommend as a starting point'
The question I really have is what carb body to put with it. You mention in your reply examples with 43 & 44mm bores/throttles. I can only assume that these were bespoke made carbs. Is this correct ?
The problem I have, given that 34mm or 36mm chokes is where I need to experiment is that I need to choose 40mm or 46mm throttles as I don't have access to bespoke throttle/bore sizing. Once I've made this decision I'm fairly stuck with it.
The problem then comes that 34mm chokes are at the upper end of the recommended sizing for 40mm bores/throttles, and 36mm chokes are at the lower end of the recommended sizing for 46mm bores/throttles.
So which carb body do I choose before the engine is tested is my problem ?
Do you have any further advice on this ?

(Another factor is that the 46s would allow more scope for increasing capacity back to 2.7 litre but this is not what is driving the decision for selecting the carbs for the engine as it is so ignore this - It just means that if 46s with 36mm chokes would work then the customer would prefer it)

Many thanks
Andrew