More Holley 4160 issues

Hi, I finally managed to get the Tique wet last weekend after fitting a new (to me) 4160. My original carb had the choke removed by the PO so I sourced a second hand replacement. After a couple of 10 minute sets the engine wouldnt fire up, carb was leaking from the secondary boosters and had flooded the engine.
There were no other boats out so I had a looong walk back with boat in tow until the fuel had dried up enough for the engine to fire up to get us back to the slip.
After flushing the engine out, it was shut off and fuel was then dripping from the primary boosters, this is an issue I had with the previous carb which was solved by adjusting float height.
So my question is, does anyone know what the measurement should be for the inverted float height? Im guessing the spec should be different to an automotive carb due to marine engines being at an angle. Also, if anything my engine is mouted at a higher angle than typical nautiques as I had to use 1" shims on the front mounts to get alignment to the shaft log. Any thoughts?
Thanks

Anyone? Planning on pulling both fuel bowls tonight and bending the floats, purely guess work though. Is there a risk of me going the other way and having not enough fuel in the bowls? What would the symptoms be?
Thanks

Thanks for the reply, the fuel pump looks original is a double diaphragm - how would I check the pressure? The previous carb I managed to run ok after float adjustment

Aditionally, did you see any red sediment in the fuel bowl? If so its a paper gasket in the fuel pump behind the one-way valves. It can shred when a one-way valve losstens and rattles back and forth, shredding the gasket.
It likes to clog needles and seats

Have cranked both floats down and no dripping after running a full 200L drum of water, fingers crossed for the next outing on Sunday. A late night of working by car headlight, I have to make use of what little time I have these days - joys of parenthood!!! :)

malcolm2 wrote: The small pump under the primary bowl, with an arm that is operated by the throttle. I believe mine was adjusted to be activated even in neutral. I adjusted the nut on the black lever in the photo below until it was slack against the pump's lever.

I think you need to study some basic Holley carb technical info. What you're referring to as a "primary pump" is actually your accelerator pump. This pump does nothing until you actually start moving the throttle. It is not a valve that opens, instead it is a diaphragm that simply squeezes a set volume of gas into your accelerator nozzles during acceleration. This is to prevent a lean condition during the opening of the throttle, before the carb can transition to the main circuits.

So what I'm saying is the accelerator pump should not be making your boat idle rich, or even start rich, unless you are sitting there pumping the throttle.

You are correct that this could need adjusted, but typically the adjustment is warranted because you're getting a backfire/stumble during acceleration.

Lots of good info here

malcolm2 wrote: I may not have the lingo down, but you knew what I was talking about. I did not know if he knew the lingo either, so a few extra words directed you right to it and it could cause flooding if it is mal-adjusted. If your boat is running and you put your finger on that pump and squeeze, gas will enter the carb. It might flood, it might just rev-up. so imagine that the bolt is adjusted so that it is pushing on the pump all the time....

No issues on the lingo Clark, I think most here will just try to get the correct terminology posted to avoid confusion in the future if someone were to revisit this post. I'm just trying to make sure you're not mis-diagnosing symptoms, and I'm still not sure you understand how the accelerator pump works based off of your statement.

If the accelerator pump bolt is adjusted so it's pushing on the pump lever all the time, it wouldn't affect anything related to idle air/fuel ratio. That pump does absolutely nothing without movement. The diaphragm inside it squeezes fuel out as it's depressed. I think you're mistakenly thinking that it is a valve that is opening and letting pressurized fuel flow through it. You could relate the accelerator pump to a rubber ducky squirt toy. You squeeze to squirt the water(fuel), and then relax it and it'll suck up more water in preparation for the next squeeze. So in your scenario, if you were to squeeze the ducky half way and just hold it there (analogous to having the accelerator pump adjusted where the bolt is too tight), it would not make any fluid come out until you were to start squeezing again (opening the throttle). The only effect you would have is that you're reducing the overall capacity of the accelerator pump.

The float just controls the level of fuel in the bowl. The level is critical because it is the fluid column pressure that provides the correct air/fuel ratio (everything else constant)..

So a low float will run lean.

Doesn't come up very often, but I have seen floats with cracks in them. Then they absorb fuel & don't float so well.   This will make the carb rich.

All really intersting stuff - thanks. It seems Ive managed to adjust mine within tolerence as it drives really well now. Took it out on sunday and didnt shut the engine off for 3hrs until getting back to the slip as was worried about getting stuck (again). Once we got back I whipped the flame arrestor off before switching off ignition and NO DRIPS!!!

Couple more carb questions. First what color accelerator pump cams does everyone run? And second what is this vent thing on the top of this bowl? It doesnt seem to do anything.

I have suspected that I may have a franken carb, am I right?

Orlando76 wrote: That's a boat anchor.

Noted!

The problem has come back
I hadnt got the boat out for a few weeks due to various commitments, after which it took a lot of cranking to get the engine started. At the time I assumed this was down to fuel (gas) evaporating over time in the summer heat. The more I think about it this was probably due to fuel leaking from the carb again. Now when I fire it up the carb really floods from the primary boosters, the engine started up straight away after leaving for a further week but as soon as I shut it off I could hear the fuel gushing out.

Next step is to adjust the float levels (again!) but they will be shutting off really low now, blow compressed air through the vent holes, check needles again and check the floats for cracks.

Can anyone think of anything else I should look at?

I am starting to seriously consider ripping the carb out and moving to LPG but this really is a last resort, and an expense I can do without..