2 weeks a go I put a new gas tank and sending unit. Last week my rear carb was coughing up gas so I pulled the needle and seat and cleaned it. Today it was surging on the freeway. I got home and checked the sight plug. Gas was pouring out of the sight hole. I adjusted the float down a little and no gas was coming out of the hole. Not even a dribble. This was with car off and shaking the car a little with my hip. So I adjusted the float a tad. Now gas is pouring out of the sight hole again. I did put the float in a cup of water and noticed no bubbles. Does this sound like a bad float? I noticed the the idle was about 1400 when the float was high. Can the idle be high with a high float? I did order a new float just in case.

IIRC, if you center the float in the bowl with bowl inverted, it will be close. Other than that, it's tough to use the sightglass method if you don't have electric pump. (eng shakes a bit with engine running the mechanical pump etc).

I did that and gas was pouring out so I lowered it a tad and not even a dribble.

I've worked on these & the Vette Tri Power
I set the floats with the bowls in my hand,upside down with the float flat & parallel to the top of the bowl
Check your seats as the ethanol enriched gas will groove the rubber & sometimes make it crack
I change them to ones for alcohol use

The float is nitrophyl,you will see no bubbles and there are very few problems with them,change the needle/seat and center the float !!

I did change the needle/ seat and centered the float inverted. It seemed like a stuck float. The new float is coming today. It's weird. I did not have this problem before I changed the gas tank and sending unit.

Do you by any chance have the aftermarket jet plates in your outer carbs? I ran into one that the float would catch on the jets and do what you are seeing.

Yes. I am using the Promax jettable plates for the outboards. I've been using them for the last 8 yrs with no problems.

debris (common,need a good filter). bad needle/seat (common). float linkage hanging up (possible but less likely)

How can it be debri if it is a new tank and unit? I did notice that the jets were black. I can remove the black with my finger and they turn gold again. Is that from the alcohol that's in the gas now a days?

New doesn't mean clean

(1) alot of debris gets by the gas stn filters (2) I believe so yes. #1 need a high quality 10 micron filter right before the carb inlet

X2

I've seen guys go back through the carbs and retorque the bowl gaskets...The added compression made the float come in contact with the aftermarket jet plate after years of trouble free service so it does happen...

Take a close look at the float and see if it has tiny marks where one or both jets contacted the float.

Thanks for the suggestions. What I did was took apart the rear carb and cleaned it. Replaced the needle/seat and float. Changed gaskets. Set the float inverted. Got it running. Took it for a small ride and came home. I left it running and checked the sight hole. With it running it just trickled out. Right now it's running good. I know in a couple of weeks, I'm going to take off the center carb and do the same thing. I think it was the float hanging up. Crossing my fingers.

With a good filter I'd say you are good. only prob with doing multiple fixes at the same time is you dont know which one was the culprit but we cant argue with success. I hear properly setup 6 packs are a killer

That's why I'm waiting a couple of weeks to do the center carb.

What fuel pressure? My friends 6-pack was doing the same thing on both end carbs, but not the center carb. I think he had 8 or 9 psi, and the pressure was bending the aluminum flat arms. We noticed the end carbs had the floats with the aluminum arms, and the center carb had the brass float arms and we did not have an issue with the center carb. We lowered the fuel pressure, re-bent the float arms so we could adjust the fuel level (we maxed out the needle/seat adjustment tring to set the float level.)