Fit a fuel pressure reg and you should on the money. Fit it the following order. Facet pump, carbs ( with a return, so that fuel will flow past them) then the fuel regulator. Any access pressure will be bled off and return to tank. This method ensure a constant even supply of fuel.

Benny, dd... I already have a facet electric fuel pump which is certainly adequate, not a standard A12 mechanical one.

Yes, balance those carbs properly by using a piece of hose. Or pay a professional to do it.

The stock A12 fuel pump volume is 500 ml/minute, or enough for a 120HP engine. Test it by timing it at idle for 60 seconds, it should fill a half liter container. It will ouput even more at high RPMs, at least up to 6600 RPM there is no problem.

Be sure to check the volume of fuel the stock Fuel pump is supplying. The PSI rating is important but volume is more important. If it cant keep up with the comsumption, you have no hope of carbs working to their potential. Weber DCOE's like 2.5 - 3PSI. Dellorto's like the same.
This is more critical when sustained high revs. A street car not so much. Also with mechanical type fuel pump that run off the camshaft, as the rotational speed of the camshaft increases the mechanical arm in the fuel pump can start to float and bounce on the lube, similar to valve bounce in the valve train and can start ti not pump fuel as well.
I run an electric pump which helps with consistent even delivery of fuel independent of engine rpm.

When I made the switch to running e85 ethanol fuel this becomes more apparent dew to the increase of fuel required for a correct A/F ratio. ~35% to 45% more fuel is used. Thin walled emulsion tunes and ~170 main jet size to feed a 1527cc A15.

Electric pumps can be had from the early 720 utes, I think some patrols had them also. facet make quite a few and so does nismo.

electric fuel pumps.

A piece of pipe is much easier and more suitable than a carb balancer. You simply listen for the noise difference and adjust accordingly.

I've owned many sets of carbs and tuned lots of them too. I use a length of heater hose.

haha I am aware that fuel pressure is not related to jetting or whether its rich or lean, was just a question as I noticed it was a bit high. Also I would rather either buy a manometer or get it done properly than use a bit of pipe in the shed and guess haha
But cheers for the specs man, that is what I was after...

No manometer is needed. Many, many people synchronize carbs with a length of tubing and listening by ear -- and adjust it accurately too.

5 PSI is good, unless the float bowl overflows -- you'll see it run out. The fuel pressure is not directly related to the jetting, because the fuel bowl is vented to atmosphere. Instead, the fuel bowl *level* sets the baseline. By contrast, with EFI the fuel pressure directly relates to rich/lean setting. So check the fuel bowl level - too high means too rich, and too low results in lean mixtures.

Weber will not warranty that their inlet valves will close at 5spi (but usually they will). Mikuni recommends 2.84 - 4.98 psi. Dellorto DHLA I've heard will run great at 2.5 to 4.4 psi.

A stock A-series pump is high volume and with the correct pressure for carburetors (2.8-3.8 psi). But the original 1970-1973 A12 fuel pump is spec'd at 2.6 psi, so check the pressure with a vacuum gauge. Later A12 is spec'd at 2.8 psi. Always test to ensure it is within specs.

yeh need to get it tuned and balanced properly, I could do it myself if I had a manometer, but not buying one when a DECENT one is more expensive than just getting it done at a reputable tuner... just noticed the fuel pressure the other day and was curious as to what was an ideal pressure. It has an electric pump and just a pressure gauge at the moment, gonna need to get an adjustable fuel reg to bring it down to 3.5 psi... cheers ddgonzal and cyclons8 :)

Carburetor fuel pressure should be approximately 3.5 psi for all brands, including Dellorto.

Popping indicates lean jetting
Running rich indicates it needs mixture adjustment

Popping is symptomatic of a lean mix, the stalling could also be a result of this.

They need to be reset and balanced properly. I could have done for you in a matter of minutes if I was close by!

Do you have a manual for them to guide you through mixture settings and balance?