Race Engine Forum UK

Hi,

I need some advice setting up the twin DHLA's on a X1/9 1500. The car is used on the street with the dream of getting it to a closed circuit every once in a while just for the fun of it.

Specs:
1500cc stock engine.
Stock head.
Flywheel lightened 800gr.
Free-flow 4-1 exhaust (2.5" is a little on the large side, I know).
Twin Dell'Orto DHLA 40's (restored).
Cam reground as follows: 112 degree lobe center
35-75 / 75-35 (seat-to-seat)
231 (int. / exh.) degrees duration @ .050 lift
10.43mm (.411") maximum lift

The carburettors are setup for an Alfa 1750 (I think) and the car is running reasonably good on higher revs only. What I'm looking for is a solid basic setup for the carbs to start with. I'm in no need of maximum performance but rather want the engine to run well and be as easy to drive as possible with this setup.

The jets as of today:
Main Jets: 7484.145
Idle Jets: 7644.52
Emulsion Tubes: 7772.8
Air Correctors: 7485.210
Idle Airs: couldn't find a number
Chokes: 8383.32
Auxillary Chokes: 7848.3

It would be interesting to hear your view as to which jets could be suitable!

Best regards,
Johan Brusefalt, Sweden.

Before I advise on this I want to suggest that you get rid of the reprofiled cam, they just don't work in n/a 8v SOHC and TC units, by which I mean you'll never get a decent torque curve.

GC

So the cam is better suited for a turbo conversion? People are apparently using them.

Anyway, I still have the stock cam and I could of course switch back, but I would like to try out this configuration. As I said it's not maximum performance I'm after, the car is starting off as a project for having fun. The state I'm currently in with this project is pretty consistent with this chioce of cam-shaft. I'll go ahead with what I have and work my way up from there when the budget allows me to do so.

How much influence does the cam have for your thoughts on the Carburettor jetting? How would you jet this engine with the stock cam?

Thanks,
Johan Brusefalt, Sweden.