Expert: Everett Peacock - 5/10/2008

Question
I have a 1989 OMC Cobra, 351 5.8L, Ran great everytime before, sat for a winter and wouldn't start. found that it was bad points, so changed points. started up and sounded great, but when you run it at full throttle it starts shaking violently.  Its smooth at idle and to about 35% throttle, anything more it starts shaking and a loud sucking noise when at full throttle. I have changed plugs, fuel filter, rebuilt carb and played with fuel air mixture, full tank of gas with stabilizer, points. Checked compression on all and they all have plenty compression.  After replacing plugs, and running and finding no change, pulled plugs and found they were black and fouled. What am I'm overlooking?

Answer
you should replace the condensor when replacing the points... and make sure they are gapped correctly.  the sucking sound sounds like a carb problem..while running try to pin point where the air leak is...you can use a hose to your hear on one end and move the other around the engine to find the air leak if it has one..
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