DHLA40 carb woes.

[simmi1983]

Hi all,

Ive overhauled my DHLA40 carbs on my Alfetta 2 litre nord with new carby kits because I was chasing a no power scenario. When I snapped the throttle to full throttle( it would just splutter and not rev) so I did all the seals, gaskets,  cleaned everything and checked the float levels etc and put them back on. Cleaned the plugs,checked compression and fired it up. Now it won't idle and seems to run out of fuel when I hold it steady at 2500rpm. I've made it worse!

Here's what I've done.

*I've rechecked the float levels- 15mm from gasket to floats and 27mm from body to fuel.
*Started at a base of 4 turns out on the mixture screws and then winding them out slowly to try to get it to idle- still won't idle
*Checked the ignition timing- ok.
*Reset the balance screw and even checked looking through the progression holes.
* constantly cleaning up fowled plugs everytime I try something new.

Here's the interesting 2 things.
 
I have 3psi fuel pressure but when I crank it over with the fuel line into a bottle I only get 120ml after 20 seconds.. surely this isn't enough flow right?

The 2nd thing is when the engine is off and I pump the acellerator to activate the accellerator pumps,  I can hear the rear 2 squirt a significant time before the front 2 do.

Any insight to what's going on would be awesome but mainly I'm concerned about the accelerator pumps not squirting at the same time.

Thanks in advance,

Luke

[giulia_veloce]

Well Luke
Lets start with the accelerator pump circuit.
Remove carbys including the carby tray.
With Fuel in the carbys,,,activate the throttle and see how much fuel squirts from both carby accelerator pump jets.
4 jets of fuel.
These are adjustable
Better if you have Pump Jets that squirt straight out of the butterflys and not straight down
Both should squirt the same and stop at the same time.
Did you clean out the accelerator pump jets and the acc pump jet circuit.
Feel free to message me for a phone call to save the texts for more and better understanding

[simmi1983]

Hey Giulia Veloce,
Sorry for the late reply, I've been busy with my other alfetta has decided to play up too so I've been focusing all my attention on that this week.

Sorry but im a mechanic raised in the EFI age, but I'm trying g to get the hang of this carby stuff. How do I measure the ammount of fuel that comes out? Where's it gonna squirt?
I cleaned put all jets by blowing air through them.

I had the venturis and chokes out and cleaned them too. The manual says not to remove them.  Have I done a bad thing by doing that? I couldn't imagine it doing any harm at the time.

Thanks,
Luke

[simmi1983]

Update. I got it running mint. Turns our the carbs weren't balanced perfectly. Just a little bit out majes the world of difference. I then used a gunson colortune and rechecked the balance and now it's mint.

Thanks for the help.

Luke

[Colin Edwards]

"Gunson Color Tune"........that's a name I haven't heard for a long time!

[LukeC]

"Gunson Color Tune"........that's a name I haven't heard for a long time!

I still have one that I bought when I was 20 odd years old (near 40 years ago!) 

I last used it few years ago to get the initial idle mixture screw setting on a V12 Ferrari I did a full carb overhaul/tune on. Worth its weight in gold. Final setting when warm done by ear and fingertips.