Re: Mallory Ignition Distributor
Dying at idle is one thing, no revs above 3100 might be another or same thing.
Just do your basics. Get your coil solved. Check that fuel pressure, not hard. I'd expect a lean pop under load if there's a fuel supply issue though. Check idle rpms to about 750 neutral, 650 in gear. You can set idle mix by listening for the sweet spot between lean and rich, or put a vacuum gauge on it and find the most vacuum at idle. Timing should go to 30 or 32 degrees all in, maximum advance. Early heads supposedly can take a little more advance than Vortecs. If they are Vortecs keep it to 30 degrees. Set your base timing to make that maximum occur.
If you want to check the Quadrajet secondary air door tension you need a really short #10 torx bit in a little stubby fixture. Then you need about a 3/16" or 1/8" straight blade screwdriver, I use one of those little pocket screwdrivers. You HAVE to keep at least a little tension on the spring with the little screwdriver. While holding the screwdriver in the slot reach under the air door spring and unlock the tensioner with the torx bit. Set the spring between 1/2 and 3/4 turn from zero tension. Mine works best at a little less than 1/2 turn.
Don't just loosen the torx and let the spring free or you'll have to take the carb back off like I did. What a PITA.
3100 rpms is lousy. Unless the boat is barnacled, waterlogged or there's motor trouble, you should be seeing over 4300 at wide open.
Good luck, we have confidence!