Holley 4160 - Mixture screws not doing anything

[MurkyAsparagus]

When you rebuilt the carb did you change the gasket between the throttle plate and main body? There are several different ones and possibly the idle ports or transfer slot holes could have been blocked off.

This reminds me that I should make an update, gasket was the same.

 

[MurkyAsparagus]

Update - Got it fixed!

I went through just about everything with no luck. I was able to get in contact with a person that's very well known in the MasterCraft community with these Holley 4160 carburetors. He told me to go 1.5 out on the mixture screws and 1.4 turns in from contact for the speed screw. These were nearly what I had, but it fired right up and worked as it supposed to. So, either some very finnicky settings or, like how things seem to go, it magically works after I exhaust every options and don't know why.

This boat has never idled the way it does now. If I could upload a video, I definitely would. Don't feel like going through the hassle of uploading to YouTube.

 

[PontiacHO]

Good work. You never gave up. Sounds like that series of Holley carbs is more sophisticated than the old “hot rod” street versions.

 

[JeffKeryk]

Congrats @MurkyAsparagus. Curious.. What was the idle speed when you started? Is it possible the idle speed adjustment was just a little too high?
Just spitballin' here.

Regardless, isn't it great when you get it and they work right?

 

[MurkyAsparagus]

Congrats @MurkyAsparagus. Curious.. What was the idle speed when you started? Is it possible the idle speed adjustment was just a little too high?
Just spitballin' here.

Regardless, isn't it great when you get it and they work right?

I was right around 750 RPM idle speed on my tach. Honestly, I thought I was in the right RPM range and everything for what it was supposed to be. RPM didn't exactly change with the speed screw adjustment when I got it working. It may be at 700 now. It's hard to tell on a mechanical tach. I have one of those photo tachs I can use, just forgot it.

I'm just happy it works! I don't know what changed, who knows?