If both engines are doing the same thing I cannot imagine it being something in the distributors. Chances of both of them failing at the same time in the same way are pretty darn slim.

I would be going through the entire electrical system and checking all connections. Especially grounds. Take every thing off, wire brush the terminals and put it back together.

Delco Voyager EST igniton

See last sentence of post 18.

Not sure if that applies to your setup or not but might explain no change in adv.

Actually, I think it’s opposite but it’s showing the way it is because it’s probably getting into the mains a little. They should hold a good in gear and not have such a drastic drop from out of gear idle. I went through some old threads yesterday and found the same issues. Most were due to lean conditions and overcompensation of the idle speed adjustment.

I’ll need to baseline the transition slots again and this time actually try setting everything in gear.

Have seen that thread. I don’t have anything plugged into the 4-pin port. I set timing based on the maximum. Good catch though!

Gotcha. Sounds like a bad ign module as you suspected prev.

It will be interesting to see if the other eng has the same "no adv" issue.

GM Carbureted Engine Distributor Module 10482830

General Motors system. Used On: Marine Inboards w/ GM Engines. Replaces: Marine Power 0807-006M5, GM 10482830, 16139399, D1965A; Mercury Marine 811637, 811637T, 850487; OMC 3854003

I used a D1965A module years back on a carb’d boat and it worked fine. I can’t answer how thr more recents are.

I just installed some DUI 000444 modules and they seem to work fine, FWIW.

It advanced for sure. But it also didn’t want to return. It seemed to also want to throw a lot of advance to it at startup a couple times (we thought the battery was quitting). Similar to a hot engine, very advanced initial timing symptom. I manually backed down the timing and then it would turn over and started. For whatever reason, it was hung-up. That symptom didn’t happen again, but it for sure held timing at 34/35 at idle speed. Shutting down and restarting was fine, but the light died so I couldn’t see what it was doing from there. She went on the trailer shortly after.

Thinking a couple of issues… carbs out of whack. And something odd with this distributor.

I like their stuff. Might be worth a call to see if they know what kind of base timing their module has.

These numbers are for carbureted apps so I’d think they’d work fine. Finding one that isn’t a knock off is the hard part.