IDA3C Weber Troubleshooting Options

[Cfletch]

Hey there everyone, working on getting my 6 conversion going here and I was able to hook up a temp fuel system in place of my tank while I am waiting on a few parts. I wanted to get the car to idle with its new fuel pump (not yet regulated down to 3.5psi) rated at 5 PSI max. I wanted to get the carb bodies full of fuel and get some pressure into the system and as soon as the pump turned on with the ignition the carbs essentially started dumping fuel down my intakes. Almost as if there was an internal leak causing fuel to just enter their respective cylinders. I'm new to down draft webers so this confuses me. I popped the top off of one of the carbs and noticed the fuel level was extremely low in the bowls so it was not like the needle and seat were stuck or a float was stuck causing it to overfill. Kind of stumped here as these carbs are rebuilt. Really any suggestions are good here. the float level was set, the needle and seats are good and not sticking at all.

I read somewhere but not in much detail that the bowls are vented? I have these little plunger-esq things in each vent tube that I have not yet pulled out. Would that be the source of my problem? If the bowls couldn't vent its just pressurizing the changes and causing the fuel to just leak down into the engine?

[Graydingo]

How are you verifying the bowl fullness?

What do you mean by "i have these plunger things in the vent tubes"

Did you set the floats correctly? You need to pin the float loosely to the inside of the carb body using a piece of folded up paper and check with a micrometer to see that the top of the float is adjusted to 12.5-13mm from the top of the carb body without gasket. Then you need to check the tab height relative to the carb body and that should be 18mm. The float tabs can then be adjusted and make sure there are no indentations where the needle touches it.

The second part is then using the float gauge to see where the floats fill. This can be done without starting the motor, just the fuel pump. If the bowls are not filling at that point, something wonky is up with your measurements or where the floats are.

Aftermarket plastic floats suck fyi. The brass ones are king imho.

Brass floats can become holy if you use compressed air in the bowls. Check their buoyancy.

Once you've set the floats, then you can do minor adjustments using the different washers on the float needles. But the bowls should still fill up as long as the floats are set pretty close to the above way.

Could your rebuild guy have messed up setting the floats so that they turn the needles off at 1/4 full?

Is fuel leaking out in both bowls by the time you take the tops off to inspect? (unlikely but possible)

Most likely it's the floats are wrong.

As for your needle test, yes you are good. They should move freely, Sometimes they will stick when holding them upside down.