DHLA 40H jetting on 2L Fiat 131 engine

[EvanR]

Hi Guy, I have just put a 2L from a 82 131 in a Lada 2107.

The engine is fully reconditioned and standard except for the addition of 132 1800 pistons. It has a standard 4-2-1 exhaust and is running the Marelli electronic ignition.
I am trying to set up a pair of DHLA 40H’s and was hoping you could point me in the right direction regarding jetting.
At the moment they are set up as the following:

34 chokes
155 mains
11 emulsions
210 Air correct
60 Idles
40 pump jets
150 needle valves
#3 Aux venturis

the carbs have been reconditioned so are in good condition. She is idling very rough and very high(1500rpm)with some spitting back and popping off idle - but once you put you foot down and get onto the mains she goes well.

This is my first venture into sidedrafts so I would appreciate any help on in what direction I should head from the above settings.

Regards
EvanR

[Guy Croft]

34 chokes - OK
155 mains - too big go 140
11 emulsions - go No 6
210 Air correct - too lean go 170 or 175
60 Idles - too rich go 45
40 pump jets - OK
150 needle valves - OK

spitting etc - do a compression test dry and wet make sure it's not a valve sealing issue. If OK (180+ psi dry, engine fully warmed up by driving ie: hot, throttle wide open, same or fractionally higher readings with tsp oil in bores) then it could be down to:

1. Dirt in idlejet
2. Too lean - idle mixture screws need adjusting
3. Out of balance
4. Blocked or dribbling pump jets - they should produce nice laminar jet when throttle is depressed.


Search in GC Q&A under 'colortune' and you will find some useful info that follows up on this. Buy a Colortune (see links).

Sorry for brevity but I am pretty tied up at the GCRE works today, hope this gets you started.

GC

[EvanR]

Hi Guy,thanks for that just a couple of questions to clear everything up in my mind.
Is it ok to put tube No6 in 40H emission carbs- I have read they needed to have emulsions 9,10,or 11.
and that you need to keep the idle jets up around the 60 mark
regards EvanR

[Guy Croft]

60 idle jet is way_too_big!

Go with the size I have indicated. As far as emulsion tube - just to be safe, please check that what I have recommended is compatible with the type you have - email Matt Cooper at Eurocarb, their website is brilliant for listing all the parts available. Eurocarb are the leading experts on Dellortos.

http://www.dellorto.co.uk/merchandise/p ... ectionID=1

Hope this helps,

G