Any "Fine Tuning" secrets on adjusting Carburator Idle Mixture screws??

[Jhenry72]

I have a 1975 Mercury 1500 and Finally after numerous hours of replacing this and replacing that, I actually got it to open up on the water! I have the Idle mixture screws set out a turn and a half from lightly seated now and I can get it up on plane, but has No hole shot. I've tried turning the screws out just about 1/8 turn each to see what happens, but it seems to have a hard time running at Idle and Dies. I've turned them back in about a 1/8 turn from the starting point and it takes a long time to get on plane. Like it's starving for fuel..? I've checked the Prime Ball and it stays hard. And when I try to pump it, it kinda boggs it down. Is this just a "Finesse" thing that you have to keep adjusting to get right?? Or is there a trick to this??

From a Non-Running engine and NOT having ANY outboard mechanical experience, to being able to go 45mph across the water by just Researching and Reading the Advise on this site, Truly has been GREATLY Appreciated!! :clap2: Not to mention, saved me Hundreds$$$$ Once Again, Thank You!!!

 

[Chris1956]

Re: Any "Fine Tuning" secrets on adjusting Carburator Idle Mixture screws??

On that motor the bottom carbs will run a bit richer than the top carbs. So, when on the water, warm engine, idling along, open the top carb 1/8 turn and test hole shot. Next open mid carb and test hole shot, follow with bottom carb, and test hole shot. Repeat sequence, as long as motor's hole shot improves. If performance starts to drop, restore previous setting and try another carb, until performance is maximized. You should find that the sweet spot is having top carb the most rich, followed by the mid carb and then the bottom carb. The settings are usually different.

 

[Jhenry72]

Re: Any "Fine Tuning" secrets on adjusting Carburator Idle Mixture screws??

Thanks Chris! I will try that out! But just to make sure I understand you. I only adjust 1 carb at a time? That would make sense to me!! Thanks Again!