Weber carburettor - jet size?

[Jimmy]

With the new parts now delivered for replacing the cast iron cylinders and low pressure 'T' spec pistons to the Mahle 'S' spec together with new higher lift cams my attention now turns to the standard Weber carburettor. What jets would you suggest in matching the carburettor performance to that of the new components mentioned.

Car - 1968 911T 2.0
Weber carburettor 40IDT3C1

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Jimmy

[Lightweight_911]

This might provide a starting point:

[Jimmy]

Thanks Andy - Indeed, a great start.

[Jimmy]

I'll be honest, I was thinking of just changing the main jets however there seems to be more to it.

Is there an upgrade kit available?

Are all of the items listed require replacing as a matched set?

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Jimmy

[911hillclimber]

6 years ago I took my race car for a rolling road tune with webers on and a lot of the jets were special to these triple choke carbs and the amount of tuning was limited due to lack of jet size choice.

Most tuners have jets for DCOE type webers which the PMO carbs use by and large.
Some jets you could not get anywhere for the webers back then, but I think you might struggle getting new jets to use.

Maybe have a chat with Alan at Canford Classics?

[Lightweight_911]

Most/all of the jets/chokes are available.

I don't know of anyone in the UK who keeps a wide selection of IDA/IDT/IDS jets/chokes - I used to get mine from Larry Turner at yourroil.net in the US - very helpful/good price/quick shipping:

http://youroil.net/weber_carb_parts.html

Paul Abbott at Performance Oriented is extremely knowledgeable/very helpful too:

http://www.performanceoriented.com/


You could also try Chris Flavell (fetuhoe on DDK) at Fenn Lane Motorsport - he refurbishes many sets of Webers & Solexes & makes many of the parts too.