You definitely need good grounds with that system. You could also have a weak coil which is entirely possible.

The V8 24 is probably the right module unless you're having problems with low-speed manners around the dock. You should be good there. Out of curiosity... what's the base timing set at, and what's the timing all in (say 3800)?

Another thing you could check is the wiring at the module. You mentioned that water was spraying everywhere because of the speedometer tubing. Perhaps the connector has some water in it? My V6 module died that way.

Hunter, once I had a guy helping me with my Holley it started running poorly and I could have sworn I had an ignition problem. Investigation found he put the secondary carb filter in backwards (flat solid side to fuel rail=wrong). It fueled up the rear bowl fine at idle but under load it would run short of fuel and cause stuttering hesitation and crappy performance when secondary's were opened. Obviously when checking the squirters etc. all looked great. Just saying.

Agreed.

And if you have a good fuel filter/water separator on the engine, I wouldn't even run a filter at the carburetor unless maybe its inline with the fuel supply of BOTH bowls.

I have a fuel water separator mounted to the side of the engine and a clear 3/8 fuel filter before it. I don't have any filters in the carb. I will check timing once the new wires are on. It seems to do very well at idle and in low speed manner. I will unplug the module make sure it is happy and clean, then smother the pins with dielectric grease.

If you are convinced it is ignition I could lend you my V8-20 module for testing. You pay shipping both ways (it will fit into the small USPS box about $7). You do have the thin triangle one correct, not the big box style.

I will look and see. Thank you for the offer!

Be sure to replace pickup/sensor module in distributor also.

Looked are those around $60?

That's it, get a genuine Merc not a Sierra/other knockoff.

This thundebolt junk sure is adding up. A dui is only $300 and it's brand new mechanical advance with 1 wire with coast guard approval.

Anyhow. I've researched until blue in the face on running an hei vacuum advance dizzy. All I find is people saying "you will blow your boat to pieces". Why can't a boat engine run a vacuum advance? I dont want to read the same stuff i find all over the Web of how it isn't coast Guard approved, and how it's one more orifice to allow spark to explode your boat. I want to know, WHY WILL IT PHYSICALLY NOT WORK?