Quadrajet!!!

[Bonnewagon]

the ongoing need to repeatedly retune the carb almost daily

That is exactly what we were discussing on the other Q-jet thread. My buddy used to tweak his Holley almost every day. I will admit it took more time to configure a random Q-jet to a different engine. But once done- you can forget about it. An original equipment Q-jet you just clean and go. The old brass floats I used to solder closed. It was rare but did happen. I think my 1967 Pontiac 400 Q-jet was the last one I saw with a stock brass float. After that they all had the plastic ones. They sucked, would flood, and you could never quite trust them. I gave up and went back to brass. I guess they improved them because they never act up at all now.

 

[rfpowerdude]

And, "flooding" by definition is an overabundance of fuel compared to air available. This happens when you pump too much gas into the intake before starting (like pumping it when the engine is warm) then it just cranks with the throttle plates closed.

However, in this case, either a sinking float, or the return line plugged causes the primary fuel bowl to overflow out of the vent tube and is sucked into the running engine flooding it out.

Flooding either way.

 

[MrSony]

Smack the top of the carb with a ratchet while its running. could just be stuck. in my limited time messing with qjets, i've never encountered a "bad" float. Nitrophyl or brass. Maybe just luck?

 

[Clone TIE Pilot]

You need to be careful ahout putting brass floats into carbs that originally had nitrophyl floats. The two materials have different buoyancies that affect the float settings. The nitro floats tend to float higher than brass so you can't use a factory spec float height for nitro on a retrofitted brass float.

 

[69hurstolds]

I've never had any problems with nitrophyl floats (I will now since I mentioned it). You're SUPPOSED to weigh the used one against a new one per the CSM to ensure they haven't soaked up too much fuel. I never do. If I'm rebuilding a carb that has had a nitro float that's been in there a while, it's cheap enough to replace it than to bother weighing it. I don't care if it's still "good" or not. Eventually, they will start to sink, and that can be a PITA, but nitrophyls live fairly long lives in my experience and I NEVER worry about them springing a leak. I guess it also could depend on who makes the unit, perhaps. The foam density between manufacturers may be a factor. But I've only used the proper part number old-school Delco floats, so there's that. Of course, there's always the possibility only one plant makes every nitrophyl float ever made. Who knows for sure. Standard has some markings on theirs that are eerily similar to Delco floats. Hmmm. Makes you wonder.

Interestingly they do claim to have brass float applications for E-jets, but I don't trust them. If they do spring a leak, they're toast right then and there. Good thing is, if it's just a pinhole, you may be able to fix it with a flame and new solder. Nitrophyls usually die a slow death. I imagine you can likely get more life out of the nitros if you set them a little lower than specified height. This way, as they soak up gas and start to sink, the bowl level would increase slowly and stay in the factory recommended level for longer. Clone TIE Pilot brings up a good point about using brass instead of nitros when setting float levels. It's not like you can set them on the fly like some Holleys.

How do you "weigh" these super light nitro floats? Below is a float scale. Fit the roach clip on the metal end of the float and hold it up by the pivot ring and read the scale where the pointer lands. Easy. You generally have Q-jet nitro floats coming in about 1/4 ounce (7 grams), if that's any help if you have one of these tools. Of course, the CSM figures you're using Delco floats of the day, but 1/4 ounce as a standard is a good ballpark. If you weigh your old float and it's at close to 1/2 ounce, you already know that's an issue. Now you know why I just replace the float on well-used Q-jets.