Weber 40 IDA 3C setup

[914Chap]

Hi,

Hopefully someone can offer some advice on where to start with my weber carbs. I have just installed a 2.4T engine in my 914. As far as I am aware the engine is completely standard, other than being fitted with weber carbs. I believe the carbs were previously fitted to a 3.0 L or 3.2 engine and as yet I have touched nothing and don't even know what jets etc are currently fitted. The engine starts readily which may suggest it is running rich? which would not be surprising if they were jetted for a 3.0 L. The engine does tick over, if rather fast at present. Before I start to adjust anything, I was wondering if anyone can suggest what jets etc. I should be using before attempting to balance the carbs and adjust the idle mixture. The Haynes manual does contain weber specifications but if I am correct these are for a 2.0 L as this was the only engine originally fitted with webers. Any suggestions or advice as to where I should start would be appreciated.

Cheers

Jonathan.

[Lightweight_911]

.
For a 2.4T engine I'd start with the following:

30 chokes
130 main jets
55 or 60 idle jets
180 air correctors
F26 emulsion tubes

Here's a useful chart for basic specs:

[mycar]

http://www.performanceoriented.com/spec ... cedures-1/

[914Chap]

Hi,

Thanks both of you for the very helpful responses. It gives me somewhere to start which is just what I was looking for. Looks like I will have my work cut out from the setup procedure, but I did kind of expect it was not going to be a 2 minute job. However, it's taken me 10 years to get this far so a while longer won't hurt.

Thanks again,

Jonathan.

[woznot]

So I now Have 2.o S cams and BPs should I upgrade my 911L carb config to 2.0 S

[Lightweight_911]

.
I would say that to take full advantage of the upgraded cams & higher compression pistons you need to uprate the Weber settings too.

Incidentally, if your current Webers are to 911L spec, I have some 180 air correctors in the For Sale section you might be interested in ...

.

[911hillclimber]

Get yourself a carb flow meter, 2 would be nicer.
If the cylinders are not drawing the same volume of air you will have mixture jetting issues. Each choke should be adjusted to draw the same.

Also, just as a general guide, look at the tuning guide from PMO in the States, I think the process described will help you.