puddlejumper410
Cadet
- Joined
- Sep 9, 2017
- Messages
- 8
OK, I'll admit up front I've got a number of things to look at - and things I haven't checked yet, but interested in leveraging your collective knowledge to minimize boat down time.
I have a 1990 Shamrock 17 with the original Merc 3.0L. I have a Rochester 2 barrel and an upgraded EST ignition.
My ignition is missing the second plug (the one which has the wire that you cross for setting timing and the shift interrupt). When looking at the EST, the plug on the left (the one that comes from the coil) is there, but the one is broken off - you can see three pins. My timing is at about 4BTDC at idle and does not seem to change with acceleration. In that, I lack top end power. I can plane, and I get about 27mph out of the boat, but it feels like there is a top end I am not accessing. In that, my tach is sticky and I don't know what I am really getting, but I think I am topping at 3500rpm or so. Resistance checks of the coil get readings that are off from the manual, but again, it runs fine...just not great. No knocking or pinging. I bought the boat 6 months ago, changed the fuel filter, cleaned the carb with a toothbrush and cleaner, but haven't checked plugs or compression or fuel pump output. I did have an issue a month ago where I would get a good hole shot, get to 28mph and then fall off after a minute to 24. I found that I had a kinked fuel line and assess that the boll of the carb had slowly been losing level at WOT due to the kink. I fixed the line and am back to a steady 28 or so. Either way, I feel the advance isn't advancing. Unrelated, but does anyone know if there should be a cap on the vacuum test port for the carb? Mine is uncovered (you can stick a finger on it and feel suction, but its not covered. Is that messing with my idle at all? Does it risk foreign material contamination, or is it just a bypass venturi?
Yep, I need to check compression, plugs and fuel pump output, but I don't really see anything that points to those. Just trying to understand the impact of not being able to put my EST in test...does it just affect my accuracy of setting timing? Should I set it to 12BTDC? Is there a way to test the distributor part of the EST? What advances my timing, is it my coil? If so, does an inaccurate rpm reading lead to an inaccurate advance? I don't sense RPM off the tach...assuming it is coming from the coil or somewhere else.
Again, we are operational, heading out for a 20min cruise later today, just trying to figure out where to efficiently go with this project.
Thanks in advance,
PJ
I have a 1990 Shamrock 17 with the original Merc 3.0L. I have a Rochester 2 barrel and an upgraded EST ignition.
My ignition is missing the second plug (the one which has the wire that you cross for setting timing and the shift interrupt). When looking at the EST, the plug on the left (the one that comes from the coil) is there, but the one is broken off - you can see three pins. My timing is at about 4BTDC at idle and does not seem to change with acceleration. In that, I lack top end power. I can plane, and I get about 27mph out of the boat, but it feels like there is a top end I am not accessing. In that, my tach is sticky and I don't know what I am really getting, but I think I am topping at 3500rpm or so. Resistance checks of the coil get readings that are off from the manual, but again, it runs fine...just not great. No knocking or pinging. I bought the boat 6 months ago, changed the fuel filter, cleaned the carb with a toothbrush and cleaner, but haven't checked plugs or compression or fuel pump output. I did have an issue a month ago where I would get a good hole shot, get to 28mph and then fall off after a minute to 24. I found that I had a kinked fuel line and assess that the boll of the carb had slowly been losing level at WOT due to the kink. I fixed the line and am back to a steady 28 or so. Either way, I feel the advance isn't advancing. Unrelated, but does anyone know if there should be a cap on the vacuum test port for the carb? Mine is uncovered (you can stick a finger on it and feel suction, but its not covered. Is that messing with my idle at all? Does it risk foreign material contamination, or is it just a bypass venturi?
Yep, I need to check compression, plugs and fuel pump output, but I don't really see anything that points to those. Just trying to understand the impact of not being able to put my EST in test...does it just affect my accuracy of setting timing? Should I set it to 12BTDC? Is there a way to test the distributor part of the EST? What advances my timing, is it my coil? If so, does an inaccurate rpm reading lead to an inaccurate advance? I don't sense RPM off the tach...assuming it is coming from the coil or somewhere else.
Again, we are operational, heading out for a 20min cruise later today, just trying to figure out where to efficiently go with this project.
Thanks in advance,
PJ