Hi,
Long-time reader, first-time poster so bear with me, please. I have an '83 Searay that my wife and I restored some time ago. Original engine was the Merc 228 (GM 305) and it has always run great -until this June when it laid down on me out on the water. With the help of some buddies, I got it out and it had dropped a valve on #3 cylinder. I decided to go back with a crate 350 marine engine (long block). I used my old intake, carb, exhausts and ignition components. I have it in now and it's doing great so far. Only thing is, I have an issue that carried over from the old engine to the new one. I think it may be coming from the Thunderbolt ignition box. On the old engine and the new, when I start up at idle, it sometimes seems to be running too slowly and sort of rough. But after a minute or so the RPM's will jump up instantaneously to about normal and the engine will smooth out. I caught it doing this one day while I had a timing light in hand. While it was running rough, timing was showing zero degrees, however, when it jumped up as described earlier, timing went to the correct value of 8 degrees BTDC. So what am I looking at here? If it is the ignition box then I will get a new one. But I'd like to be sure because those things are like $500. Any help and/or advice would be greatly appreciated...
Long-time reader, first-time poster so bear with me, please. I have an '83 Searay that my wife and I restored some time ago. Original engine was the Merc 228 (GM 305) and it has always run great -until this June when it laid down on me out on the water. With the help of some buddies, I got it out and it had dropped a valve on #3 cylinder. I decided to go back with a crate 350 marine engine (long block). I used my old intake, carb, exhausts and ignition components. I have it in now and it's doing great so far. Only thing is, I have an issue that carried over from the old engine to the new one. I think it may be coming from the Thunderbolt ignition box. On the old engine and the new, when I start up at idle, it sometimes seems to be running too slowly and sort of rough. But after a minute or so the RPM's will jump up instantaneously to about normal and the engine will smooth out. I caught it doing this one day while I had a timing light in hand. While it was running rough, timing was showing zero degrees, however, when it jumped up as described earlier, timing went to the correct value of 8 degrees BTDC. So what am I looking at here? If it is the ignition box then I will get a new one. But I'd like to be sure because those things are like $500. Any help and/or advice would be greatly appreciated...