Too much fuel at idle

"Still, the same '97 5.7L,

"Still, the same '97 5.7L, 2bbl mercarb. Still hard to start when warm, and still rough idle.
Tore the carb apart, found no smoking gun. Put it back together. With the idle mixture screw completely shut, I can see what I think is a lot more fuel than it needs at idle, flowing from the venturi into the engine. If I keep the throttle open a little past idle, it'll get enough air to keep running... with a little bit of smoke. When I turn it off, I can see fuel continue to pour into the intake for a couple of seconds... which explains the hard starting. And the fact that it's still getting fuel at idle with the idle mixture screw completely shut explains the rough idle. Now for the tough question... what is causing this?
The float is adjusted properly. The needle and seat are new. All gaksets in the carb are new.
Power valve is new. Idle mixture needle is new.
After studying the diagram, I see there is a ball check at the bottom of the accelerator pump cylinder. I haven't messed with that at all... what would happen if that was leaking or missing?"

"That check ball closes when y

"That check ball closes when you accelerate, so that the fuel in the pump barrel is forced into the venturi. I doubt it is your problem.
There should be a main metering jet needle or valve that controls the fuel admitted to the venturi stack. Is it in place correctly?
I don't think you should see visible gas from the main venturi at idle condition. Idle fuel is controlled by the idle mixture screw alone. Something sounds wrong, and it sure sounds like the float level is too high. There should not be enough vaccuum across the venturi at idle air flow to pick up fuel. This is why there is an acclerator pump; it kicks in fuel when you hit the throttle so as to richen the mixture during the short period of time until the fuel flow to the venturi can catch up. Otherwise you will bog when you hit the throttle.
I think something needs re-checking. First suspect: float level.
Rod"

"I'll definately recheck t

"I'll definately recheck the float level. I'm suspecting the specs that came with the rebuild kit may be hosed.
I pulled up a Mercruiser Service Bulletin that says the ball check beneath the accelerator pump should be removed, if present, anyway. Appaently they upgraded the accelerator pump linkage which eliminated the need for the ball check. I think all it was there for was to limit travel of the pump anyway and had no affect otherwise.

I'm digging around for more sources of float level specs."

Just for fun you should maybe

Just for fun you should maybe try dropping the float level 1/8" or so. I bet you will find a huge difference.
Rod

"After thoroughly going throug

"After thoroughly going through the service bulletin, I found that the float specs were different than those given in the instructions that came with the rebuild kit... which I installed 6 months ago, when I went through the E-10 water absorbtion abortion... talk about chasing your freakin' tail!
Anyway, the rebuild kit said 3/8" level, and 1-3/32" drop. The Service Bulletin (97-6) says 9/16" level and 15/16" drop... big difference! According to the service bulletin, the spec depends on whether the needle valve is the older, two piece solid type (use 3/8 & 1-3/32"), or the newer spring loaded type (use 9/16" & 15/16").
Pulled it apart a little while ago and discovered that at 3/8", depending on where exactly the float was riding with regard to the little bit of side to side play it has, the float may actually hit part of the bowl lid before it shuts the needle valve (explains the intermittent part of this prolonged agony!).
I re-adjusted to the service bulletin specs and it runs like a champion!
The idle mixture actually responds the way it's supposed to!
It purrs right along at about 600 rpm, no hick-ups, no burps, no sputters!
And, best of all, no fuel dumping straight down its throat when I shut it off. Which in turn means it fires right back up, throttle in neutral, all I have to do is bump the starter and it kicks right off! Wonderful! I'm elated! I'm celebrating with copius home brews!
Sea trials this weekend to confirm all, weather depending, but I think she's fit for full duty."

Great news Troy; it almost had

Great news Troy; it almost had to be a float thing.
The best news is you didn't have to Bring On Another Thousand. Yahoo!
Keep the wet side down and enjoy!
Rod

"Last night was my last-ditch

"Last night was my last-ditch effort, if that didn't get it, I already had a new 4bbl and manifold sourced and ready to order.
That may be something I want to do when I have that extra thousand and nothing else to do with it... that time isn't now!"