Home › Forum › Ask A Member › 70hp idling characteristics? › Re: 70hp idling characteristics?
OK, well this engine has the "fastrak" trim system, which trims down in quite a bit to help plane off boats better. But, you are quite right, idle quality is surely affected by trim angle and exhaust reliefs being buried in the water. You could always move the trim pin out a hole or two, if all the negative trim is not needed to plane your rig.
This engine has the dreaded "dwell linkage", along with quikstart, which make sync set up tricky. Let’s begin at the beginning though, did you check TDC with the OMC piston stop tool? If not, trying to split hairs setting up idle timing is a waste of time. Rough running off idle is usually caused by poorly synced carbs. These engine usually idle pretty well, much smoother than the two cylinder 40-50s, but the sync steps must be followed exactly and in the prescribed order. Maybe you should back off my 25:1 fuel mix recommendation slightly while you are trying to dial in the idle. Make sure the engine is getting up to temp, or it will take a long time to drop out of quikstart and idle poorly.
I would definitely move that overboard elbow up to the top as prescribed by the bulletin. There was also a bulletin about increasing high speed jet size on these engines as well.