DHLA40 carb woes.

Started by simmi1983, May 08, 2024, 07:06:02 PM

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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