My Holley 600cfm VS 4160 has developed a nasty leak.

After I drove it home from the suspension shop last week (no problem on the way home) I noticed the car was starting to have trouble turning on. I didn't give it any thought. Decided to drive the car to school on Tuesday.

Driving up a main road, as I came to stop light, the engine died on me for no appearent reason. Took LOTS of cranking and pedal pumping to get it back on and then it wouldn't Idle so I had to keep one foot on the break and one on the gas..

I pulled into the nearest parking lot and adjusted the idle so it would Idle at 1000rpm in gear to keep it on. I make my way through the twisty canyon roads and all is fine. As soon as I exit the canyons into the city, I start to feel an off-idle hesitation. About a mile from there, i started hearing a hissing sound, turn off the radio, sounds like sometype of pressurized under-hood fluid leaking. Pull over on to a side road, car shuts off.

Open hood and intake is wet with clear fluid, thought it was water. Turn the car back on, struggles to idle, sounds like an engine with a BIG cam for a while, finally get it to idle steady, run out to look under the hoold and see fuel spraying from the carb. Close up the car and walk 4 miles to school.

Come back in the after noon, unscrew the plug from the primary bowl, fuel leaks out, LOTS of it. Adjust the floats, carb stops leaking, drive it home, no trouble, no leaks.

Fastfoward to today. Fire it up to go get some chinese, feels fine while i do a 3-point turn, straighter her out and nail the throttle, do a nice 300ft run down the block, let off the go pedal, idle down the street, making left turn uphill, car start to struggle. Sputters, big-cam-style idle, shuts off.

Pop the hood open, turn car on, gas spraying again. Drive it down a block (i know, dangerous, but i had to get back home) and then shut it off and cost down hill to my house.

I take apart the front bowl/metering plate and the gaskets look fine (but A LOT of fuel came out of the sight plug again), no cracks in bowl/metering plate that i could see.

Buttoned it all back up, had my buddy watch as i turned on the engine, he said it leaked from the bottom of the carb. I looked and it looks like between main body and the throttle plate (base plate? the one where the throttle shafts are, LOL).

I've been looking for a crack but I can't find anything. Took out the needle and seat and it seems to move up and down just fine, no dirt.

What could be going on here?

Carb is less than a year old, always been run with AT LEAST one filter in the fuel line, sometimes two.

I think I fixed it.

I noticed that the metering block had quite a few casting flaws compared to the one from my older 4160, especially at the corners and just all together.

I swapped jets from the new metering block to the old one, added a new power valve I had laying around, used the same (blue) gasket the from the new one onto the old block and installed the old block on the new carb. No leaks so far. I'm gonna wait a few hot/cold cycles before i declare victory though.

I think the problem is related only to the needle and seat not sealing properly at times. If it happens again try a new needle and seat, it might be hanging up somehow? Dirt is usually the culprit but you said it was clean. Fuel will flow out of the throttle shaft bores when the bowl overflows and the throttle blades are in the closed position. High fuel pressure could cause the problem but I wouldn't think it would be intermitten but more constant. Make sure the float isn't contacting anything in the bowl restricting it's travel. Bob

Yeah, except it wasn't coming out of the throttle shaft bores, but from the front/bottom of the carb. Some from the top too. All on the passenger's side of the carb. I also checked inside the intake and there was no fuel dripping in after shutdown, as the needle-n-seat problems tend to cause.

I don't know, we'll see.