Hi all.
I have an V8 275 '88, at least that is what I am being told, an '88 mod.
It had an servo pump and special steering assembly, but since I had an hydraulic setup on the boat that fitted the engine and were working, I took the original system off.
Engine is installed on an Fletcher 21'. Motor sits on an 6" setback bracket from Bobs Machine.
The engine sits a bit low, had an 20" 150 V6 CF on it before, so the bracket is not in the upper holes at the boat. This engine has an 25" shaft and is therefore too far down. I installed it as high as I could on the bracket, but did not raise the bracket on the boat. The cavitation plate is now probably 1-2" below the bottom of the boat, so it needs to be raised. It pushes a lot of water to the sides.
When I bought the engine it had an Raker 14.5x18 propeller. The engine felt very responsive and strong. I had to adjust the throttle cable so I could not get WOT because it would just rev too easily. Did ~40knots at 5-5500rpm. But I did not push it since it felt alot like driving your car in 1st gear, nearly like free revving it. Awesome acceleration and veery easy to pull up skiers though.
Because of this I went and bought an used prop, an Raker 14.5x26. I know this is a big difference, but it felt so strong with the other prop.
Now course the problems started.
There is a big difference. Now the engine had to really work. You definitively need WOT now to push it over into plane. Goes into plane at 2300-2500rpm. I right away felt that it where missing now and then from standstill into plane on a cylinder or two. Once in plane it feels and sounds great. Trying to pull skiers is nearly impossible though, once up it is great, but it has an real hard time accelerating from stand still. WOT gives 4500-4700rpm depending on trim, but I have not measured the speed, but it feels a lot faster...
Running back from the test I felt like there were a lot more white/gray smoke out the exhaust than I feel that I have seen before.
I discovered that when using the warm up idle on the console to rev it, it just feels real weak compared to before. Takes time to rev it up.
The misfiring did seem to be less under acceleration when constantly pumping the priming hand pump.
Then I started to search for errors.
Did a compression test, first I thought about broken head gaskets.
Expected to see an plug with water droplets on it, or mysteriously clean, but they seem ok apart from being soaking wet with fuel. It starts easily cold or hot though.
Warm engine, no throttle, one plug taken out a time. Couple of cyls at 90, a couple at low 70s, the rest at ~80.
I did see that there is an fuel leak that comes somewhere behind the airbox. It slowly drips when running.
The fuel hoses are btw with an hand prime pump at 8mm (5/16) ID, 10mm (25/64" to 13/32") ID fuel hoses the rest of the way. I have heard this engine needs fuel, but it does not seem like it isn't getting fuel at all under acceleration (like it runs out of fuel), but it is working real hard on accelerating. It just feels too weak for doing the job correctly.
I have not checked the ignition advance yet, but all adjustment screws on the linkages for the carbs and so on is like they where when I bought it, and the all start at the right place and stop at the right point.
Last summer I did not use the boat very much since I did an complete rebuild of that Johnson 150 '85 that I own and had on the boat earlier, that helped alot on the performance on that engine, though nothing realy seemed wrong with it to start with.
Now I just hope that I not necessarily need to rebuild the V8 powerhead as well..
Any first thoughts and ideas would be nice to hear..
Fredrik.
I have an V8 275 '88, at least that is what I am being told, an '88 mod.
It had an servo pump and special steering assembly, but since I had an hydraulic setup on the boat that fitted the engine and were working, I took the original system off.
Engine is installed on an Fletcher 21'. Motor sits on an 6" setback bracket from Bobs Machine.
The engine sits a bit low, had an 20" 150 V6 CF on it before, so the bracket is not in the upper holes at the boat. This engine has an 25" shaft and is therefore too far down. I installed it as high as I could on the bracket, but did not raise the bracket on the boat. The cavitation plate is now probably 1-2" below the bottom of the boat, so it needs to be raised. It pushes a lot of water to the sides.
When I bought the engine it had an Raker 14.5x18 propeller. The engine felt very responsive and strong. I had to adjust the throttle cable so I could not get WOT because it would just rev too easily. Did ~40knots at 5-5500rpm. But I did not push it since it felt alot like driving your car in 1st gear, nearly like free revving it. Awesome acceleration and veery easy to pull up skiers though.
Because of this I went and bought an used prop, an Raker 14.5x26. I know this is a big difference, but it felt so strong with the other prop.
Now course the problems started.
There is a big difference. Now the engine had to really work. You definitively need WOT now to push it over into plane. Goes into plane at 2300-2500rpm. I right away felt that it where missing now and then from standstill into plane on a cylinder or two. Once in plane it feels and sounds great. Trying to pull skiers is nearly impossible though, once up it is great, but it has an real hard time accelerating from stand still. WOT gives 4500-4700rpm depending on trim, but I have not measured the speed, but it feels a lot faster...
Running back from the test I felt like there were a lot more white/gray smoke out the exhaust than I feel that I have seen before.
I discovered that when using the warm up idle on the console to rev it, it just feels real weak compared to before. Takes time to rev it up.
The misfiring did seem to be less under acceleration when constantly pumping the priming hand pump.
Then I started to search for errors.
Did a compression test, first I thought about broken head gaskets.
Expected to see an plug with water droplets on it, or mysteriously clean, but they seem ok apart from being soaking wet with fuel. It starts easily cold or hot though.
Warm engine, no throttle, one plug taken out a time. Couple of cyls at 90, a couple at low 70s, the rest at ~80.
I did see that there is an fuel leak that comes somewhere behind the airbox. It slowly drips when running.
The fuel hoses are btw with an hand prime pump at 8mm (5/16) ID, 10mm (25/64" to 13/32") ID fuel hoses the rest of the way. I have heard this engine needs fuel, but it does not seem like it isn't getting fuel at all under acceleration (like it runs out of fuel), but it is working real hard on accelerating. It just feels too weak for doing the job correctly.
I have not checked the ignition advance yet, but all adjustment screws on the linkages for the carbs and so on is like they where when I bought it, and the all start at the right place and stop at the right point.
Last summer I did not use the boat very much since I did an complete rebuild of that Johnson 150 '85 that I own and had on the boat earlier, that helped alot on the performance on that engine, though nothing realy seemed wrong with it to start with.
Now I just hope that I not necessarily need to rebuild the V8 powerhead as well..
Any first thoughts and ideas would be nice to hear..
Fredrik.
