Sashap
Petty Officer 2nd Class
- Joined
- May 1, 2016
- Messages
- 145
mercruiser 3.0.
I hooked up a vacuum gauge to the intake manifold today. It reads about 12. While it was warming, it did jump up and down about 4-5 either way. When it warmed up, the jumping levellled off to the 12 reading. I attempted to set the idle screw but it was really hard to turn. So I decided to take it out. Apparently, the previous owner put quite a bend in it so it wobbled quite a bit as I was turning it out. The bend was about 1/3 into the thread. This explains why I couldn't turn it in to set it. I have to order another screw so I can't do much about adjustment for a couple of days.
My question is regarding the timing/fuel mixture relationship.
Why is it that the timing at base even though it reads 1degree BTDC and at 2500 RPM with the base jumper taken off, it reads about 12 degrees BTDC. So basically, if I set the idle mixture better (clearly it needs it as it could run much better and stronger), will the timing improve?
Is the timing wonky? Is it just the idle mixture that is wonky? Symptoms are so so accelerations, gets up on plane a bit slow but middle performance. I just don't think it would easily pull up a skier at this rate. Also, top rpm at 75% throttle is about 3300 RPM. It planes out and goes smoothly, just doesn't feel as fast as it should. When I give it the extra bit of throttle to the top, I can hear a slight increase in engine power but there is just no extra speed increase or even RPM increase.
I read that with a properly set idle mixture it would give me the kick it needs to bring it out of the water fast and give me full throttle all the way to the end of the lever. Right now, I don't have either. I don't think it's the prop because it is a stock 19" and the prop wouldn't have any effect on the top 25% of the throttle.
Ideas Gentlemen? And Ladies of course!
I hooked up a vacuum gauge to the intake manifold today. It reads about 12. While it was warming, it did jump up and down about 4-5 either way. When it warmed up, the jumping levellled off to the 12 reading. I attempted to set the idle screw but it was really hard to turn. So I decided to take it out. Apparently, the previous owner put quite a bend in it so it wobbled quite a bit as I was turning it out. The bend was about 1/3 into the thread. This explains why I couldn't turn it in to set it. I have to order another screw so I can't do much about adjustment for a couple of days.
My question is regarding the timing/fuel mixture relationship.
Why is it that the timing at base even though it reads 1degree BTDC and at 2500 RPM with the base jumper taken off, it reads about 12 degrees BTDC. So basically, if I set the idle mixture better (clearly it needs it as it could run much better and stronger), will the timing improve?
Is the timing wonky? Is it just the idle mixture that is wonky? Symptoms are so so accelerations, gets up on plane a bit slow but middle performance. I just don't think it would easily pull up a skier at this rate. Also, top rpm at 75% throttle is about 3300 RPM. It planes out and goes smoothly, just doesn't feel as fast as it should. When I give it the extra bit of throttle to the top, I can hear a slight increase in engine power but there is just no extra speed increase or even RPM increase.
I read that with a properly set idle mixture it would give me the kick it needs to bring it out of the water fast and give me full throttle all the way to the end of the lever. Right now, I don't have either. I don't think it's the prop because it is a stock 19" and the prop wouldn't have any effect on the top 25% of the throttle.
Ideas Gentlemen? And Ladies of course!