Re: Fuel economy
I'm not sure if this will work with all V4 Crossflows, but it might be worth looking at...<br /><br />A friend of mine built up an early 1980s V4 140 out of a parts motor, doing it all by the book, save for some mild porting to the block. He's a very meticulous type, has built hundreds of motors over the years from bikes to big blocks. Builds some of the fastes 15A Johnrudes in the country for Stock Outboard.<br /><br />Anyway, after building up his engine he discovered that although it seemed to run fairly well that his plugs were consistently dark, particularly at mid-range. He checked all he could check to make sure he hadn't overlooked anything, but came to the conclusion that it was just the way it was supposed to run. So he starts ordering jets in various sizes from our local dealer and starts testing. He loves reading plugs and is about the best I have ever seen at knowing what's going on inside a motor by looking at a spark plug. He starts leaning out the mid-range, one size at a time until he can do a shut down from 3500 RPM and get a nice chocolate read on the plugs. Had to go a LONG way to do it, too, as the stock jets were way on the fat side. Took a little fuel out of the top end and a little out of the idle end, too. Discovered that his mileage nearly doubled, particularly when you consider that most of the running is in the mid-range. <br /><br />Like I said, what he went through might not work on all V4s. Might have been unique to his motor, but it is certainly worth a look. If the plugs are running carbony black, you might be running on the rich side. A little leaner on the jets might improve your fuel economy a bit and make the engine run better to boot! This is definitely something left to someone who knows what they're doing, as it's not hard to go too lean and cook the motor. They might come a little fat from the factory as a safety margin so that the motors DON'T blow up. Once I get my new boat restored and my 90hp mounted up to it I'm going to do some testing of my own to see if it holds up for others...<br /><br />Something to think about, anyway....<br /><br />- Scott
