40DCOE jets and rolling road

[Robster]

My 1800Xflow has three different sises of air jet, and 165 main jets in the carbs. It has been rolling roaded but I was never very happy with the results, and it was only when I started looking at the jets that I discovered the odd combination. I am aiming to get a 144 cam fitted soon, but in the mean time, with the current 234 cam I have changed the air jets to 155's and it has made a big difference. Can anyone with a 1700/1800 Xflow give me an idea what main and air jets your cars are running? I will get the car to Roger Kings in a few months for the cam anyway, so I am just experimenting. Still, to date I seem to have improved on the last rolling road session!

 

One lesson I have learned is that a lot of places offer rolling road tuning, but very few actually either understand how to set these carbs up (choosing correct emulsion tubes,jets etc) or carry the stocks of jets needed to find the correct setup for a particular car.

 

 

 

 

[Pierson Broome]

My car is also an 1800 x/f on 40's with a 244 cam and the best advice I could give you is to take it to Roger sooner rather than later and let him do the jetting, combined with a rolling-road session. Rog. is The Man when it comes to this and he carries all Weber jets, etc.

 

Regrettably, I don't have my jet sizes to hand (the car's in the UK - I'm in Singapore) - but Roger will, 'cos he keeps detailed records of all his customer's engine set-up specs. However, bear in mind that there may be no 'standard' jetting configuration, each set of carbs., engine build and exhaust combination differing in some slight way. That's why I'd recommend that you take it to Roger to sort out - I don't think you'll be disappointed (I've no commercial link with Roger - just a very pleased customer).

 

Pierson

[Roger King]

Can you let me know the size of choke that is fitted to your carbs. Without this information it is impossible to give you a ballpark jet setting.

 

The choke size has more influence on the jetting than the type of engine that the carbs are fitted to!

 

If the chokes have not been modified, they should have the size clearly marked. Simply look down the carb barrel past the aux vent (the small circular thing in the middle) and the choke is the constriction behind it.

 

Typical values would be 30mm - 34mm.

[John E]

Aha. Now I know why your phone was engaged this AM Roger. You were surfing werent you.

Cheque on the way today and thanks for the advice on the sump.

[Graham Sewell]

I have a 1700 xflow which I set up as follows:

 

Choke 32

Main 130

Emulsion F16

Air 180

Idle 45F9

 

These jets were then confirmed on Andrew Walker's rolling road as being pretty close. For a minor gain at peak power with small loss mid-range, the mains could be swapped for 135.

 

Hope this helps.

 

Graham