FAO CP or MC

[Cheese]

I've currently got a weber 34/36DTML on my engine (1400 bottom end, 1300 head, and 4 branch manifold).. Im looking to fit a set of 40's which I've bought. I've got the manifold (an original Nova sport one), and I've made an alternater plate and throttle linkage... The carbs originally came from a 2.0 Audi, so the jets and everything are going to be way too big..
If you've got the details available, could you post them here or mail me the info. on the choke sizes and things that I would need, so that when I take it to the rolling road, the guy knows exactly what he needs to fit.
The carbs have no ram pipes, do I need these? Is it something I can buy from a tuner?

Thanks for any advise and info..

Ben :D




:D Twin 40's on the way :D

[paulrobo]

Ben mate, when surfing the other night i came across something that will coem in very handy when changing jet sizes. I will find out the addy for ya and post it. You enter engine size, peak power and it tells you what jsets to use.

The R place should now what to do, but i wouldnt think it would be much different from the nova sport would it? Have a look in the post below and that shows the sprt jet sizes.

[paulrobo]

O.k go to http://members.aol.com/DVAndrews/

then on he first set of links towards the bottom of the page there is a jetting progreme for carbs. Try that mate.


Paul

[Cheese]

Nice one! :D

Thanks alot Paul :D

Ben :)

:D Twin 40's on the way :D

[CP]

Chokes sizes- around 30mm. Accurate details on jet sizes for 1.4 and 1.6 to follow from MC as I haven't got them any more. All I will say is that to accurately set the carbs for max. peformance you need to have the exhaust gases analysed as well as power levels monitored which is easiest done at a good rolling road. Unfortunately this can all be pricey.
Any Weber carb dealer will be able to provide jets, ram pipes etc.

The rolling road I keep recommending is Peter Baldwin near Cambridge 01223 207217.
Finding a rolling road with someone who has a lot of experience with 40's is a lottery. Peter has the ear for them plus you get to do your own driving on the rollers:)Nice!

Its usual to fit a fuel regulator as the carbs only need low pressure. If you don't fit one you may get excessive fuel consumption with the pump forcing fuel past the float chamber valve.

Buy or borrow a balancing air meter which once you have the jetting sorted is very useful to synchronise both carbs. Make sure that the butterflies in each carb are accurately synchronised with the other when you install them and that the butterfly spindles aren't bent or damaged
Once set they don't need a lot of fiddling with apart from the occasional tweek of the idle to get the car to tick over smoothly as conditions change.

The important thing to understand with twin 40's is that although infinitely adjustable, once set they are locked in. People say they go out of tune but this isn't really true. What generally happens is that as conditions inside and outside the engine change(principally temperature) altering the mixture. This is most noticeable from winter to summer conditions and in particular at low engine speeds and idling.

[MC]

As CP says, you need 30mm in an engine of that capacity. To get your mains, you need to multiply that by 4 = 120. The larger the main, the more fuel accross the range. The Air correction jets need to be around 190, the smaller the jet, the richer the mixture at full throttle. Emulsion tubes govern driveability rather than mixture, so thats one to play with, the one I had was a pig at low speeds, but was well suited to full throttle action. Idle jets are the tricky one, and I think I had 45, but I'm not positive. This governs the idle, but also is a key factor in the smooth transition between idle and main so that you don't get a stutter. The pump jet yet again I'm not positive about, I'll double check all this when I get a chance. I have got all the caculations fo it somewhere. If your not sure, your best off leaving it to the rolling road, and just saying that the carbs aren't jetted properly. They'll know what to do. just make sure you have the 30mm chokes in b4 hand to save you money. Yes you do need trumpets.

[Cheese]

Thanks Guys, Really really appreciate it :D

Cheques are in the post! lol


Thanks again :D


Ben :)

:D Twin 40's on the way :D