Holley 4160 float valves

Here's a picture of the needle and seat with the adjusting nut and lockscrew

Now I'm beginning to understand what you're saying.

You have externally adjustable floats and the new needle and seat assembly look different and you think they might work............or maybe not.

And the problem is that the threaded area is a different diameter?

Your last picture on the bottom is the internally adjustable type that came along later.

I'll have to look at some pieces parts to see what I have, but there are definitely still kits around with the right threads on the assembly.

Yeah I can't even find a picture of the style that was installed originally on my carb -- I'm assuming an old aftermarket part. I am also seeing the welch plugged versions of the 4160 online installed on PCM motors.

So does USCG dictate they must be internal / plugged? I did find pictures of marine carbs with the candy cane vents that had external adjustments...

How about the sight holes -- are those ok on the water?

I'm not certain I follow. The top item in the picture is the new externally adjustable one. The next two below that are original externally adjustable ones - or at least the ones I removed from the carb that was on the motor. I believe the new would work but the seals and lock nut are different and not compatible. I also cannot find a source from holley web page or otherwise for the original style.

Are these supposed to be internally adjustable float valves only? My kit also came with a couple of a very different style which I was speculating looked like internally adjustable. I think I need different hardware for those as well.

The Holley kit I purchased is by and large what I need but the float needles are a different style - maybe automotive?

Do I need to get the original style from somewhere (I've not been able to find the oem style) to be coast guard compliant or should I just get the new style hardware parts (below)?

new style hardware