Need to adjust Holley 4160 on 1991 OMC 4.3l HO

[kylep123]

I need to adjust my idle fuel mixture screws on my 1991 Cobra 4.3l HO and in the manual it says to start at 314 Turn Out, wondering if anyone know what this means for initial setting. The reason I am going to adjust this is because twice now when I took my boat out after about 15 minutes of running and I slow down to idle and try to get back up to speed the engine starts shaking and has no power around 3000rpms, I pulled up to the dock slowly and shut it off waited about 3 minutes started it up and couldn't get it to do it again. With new plugs and coil pack I am not sure if this is spark or fuel related, going to start with the fuel. If anyone has any suggestions on that it would be much appreciated.

 

[bruceb58]

You do realize that the idle mixture adjustment basically does nothing at 3000 RPMs right?

 

[kylep123]

Yeah I was kind of thinking that but noticed my idle is a little rough just looking for a ball park to start with going to basically go through and check all fuel supply then to the spark side of it. Not sure why this motor is doing that but only did it twice and seems to happen when I go from fast to slow then try to get it back up to speed. Last night it happened so I shut it off and then restarted and took it for another spin and could not get it to repeat so I guess its going to be pretty hard to diagnose especially since I have the HO with the coil pack which I hear is fairly rare and cant seem to find much on them. The engine only has about 10 hours on it and the compression is at 160 +/- 3 on each cylinder so I am guessing it is not an internal issue.

 

[kylep123]

Yeah I was kind of thinking that but noticed my idle is a little rough just looking for a ball park to start with going to basically go through and check all fuel supply then to the spark side of it. Not sure why this motor is doing that but only did it twice and seems to happen when I go from fast to slow then try to get it back up to speed. Last night it happened so I shut it off and then restarted and took it for another spin and could not get it to repeat so I guess its going to be pretty hard to diagnose especially since I have the HO with the coil pack which I hear is fairly rare and cant seem to find much on them. The engine only has about 10 hours on it and the compression is at 160 +/- 3 on each cylinder so I am guessing it is not an internal issue.