High Idle - Regardless of Carb Adjustment
 

Long story short, mainly the port side motor has a high idle in neutral. Both do it now, but happens most frequently/all the time with the port side. In gear, it's perfect, but after cruising/running, the idle jumps up from ~750-800 in gear, to ~1100-1200 in neutral. I have adjusted the idle screw on the carb but that seems to only effect the idle while in gear. I don't want to damage the drives.

This seems to have been brought on by timing my motors at full advance.

It's a semi built 502 MAG with Holley 800CFM carb. Timing at 36 all in, with TBIV-22 modules, which puts it ~14 degrees at idle. Im running 93 octane.

Any recommendations?

Any chance of a vacuum leak

air leak was my thought

At what rpm are you setting the base timing ? and at what rpm are you seeing full advance on the light

More advance at idlle will typically raise your idle speed You will not be able to lower the idle speed without re-adusting your cable length too. so, remove cable Do all your idle and mixture screw adustments. then adust length of cable so it slides right on without opening the throttles on it's own.

Initially I set the base timing to ~ 14 degrees @ ~ 800 rpm, which is where they normally idle. After that was done, I went to check total and make it 36 all in, which based on these modules ended up being ~ 3600 rpm if I recall. I revved the motors to 4k to ensure they were in fact all in by that point, and everything is good there. I had to adjust the distributor a little more from where the base was, in order to get exactly 36 all in. It was at this point, after going out a few times I noticed the higher idle while coming out of gear.

This is from last night while coming in, still in gear: https://i.imgur.com/Zw7fNFx.jpg

The throttle cable is adjusted properly.

Really the only thing I changed was the timing.

https://cimg7.ibsrv.net/gimg/www.off...95acc7dd23.jpg
@ 1200 rpms your module could be adding as much as 3 - 3.5 * of timing..........post a pic of the module, is it V8-22

According to this chart there are two different ones

When you adjusted the idle screw did you also adjust the throttle linkage? If not you can unscrew the idle screw with no affect because the linkage is still holding it forward.

The boat came with the V8-20R modules. I bought the more aggressive curved V8-22 modules where they are all in by 3500.

I asked the same thing above.He said cable is adjusted properly but he did not say exactly if he re-adjusted it or not.