Fuel Economy

I rebuilt a 1986 140hp with VRO just at the end of spring this year. My boat had a 1979 115hp and I rebuilt that one a year earlier. With the 115, my boat got great gas mileage and ran great. The 140 with the VRO connected gets worse gas mileage and it doesn't like to idle. My question is: I know loop charged engines don't idle so well, but just how bad are they supposed to idle? and Should I be getting worse or better gas mileage with the 140? I thought that loop charged engines got better gas mileage. I live on Staten Island and when I travel to Sandy Hook, about 25 miles round-trip, I burn about 1/2 of my 19 gallon tank with the 115 and about 3/4 with the 140. Does this seem reasonable? I travel at less than 3/4 throttle.

Re: Fuel Economy

irdir, So you are getting 25 miles/ 15 gallons with your 140. Your motor seems a bit "thirsty", but not too far from reality. Make sure your carb floats are set correctly (no flooding). Make sure your ignition timing is correct. Is your prop the correct pitch and in good condition? Make sure you trim the boat to optimum. Is the bottom clean?<br /><br />Remember this motor could use 14 gal fuel/hour at full throttle. It is important that you get maximum speedout of the setup to lessen it's fuel consumption.

Re: Fuel Economy

When I did the rebuild I got lazy and didn't want to clean each carb so I just put them back on and synchronized them. I also never changed the timing of the motor because the owner who ran it last said it ran fine and I never touched the timing during the rebuild. The prop is perfect and I always trim to optimum (not to high/not to low). The bottom is clean but pitted since the boat is a 1972 Cobia 16'. Any idea on how to fix the pitting to make it smooth again? What shoud i expect to get for speed if i'm running a 13x21 aluminum prop?

Re: Fuel Economy

Sorry, I meant a 14x21 aluminum by Michigan.

Re: Fuel Economy

Horsepower takes gas. More horsepower takes more gas. Believe me if you could find a way to get More power from Less gas, you could be richer than Bill Gates.

Re: Fuel Economy

If the looper is set up right it should get better mileage than the crossflow. It will burn more per hour but youll go further in an hour.<br /><br />Start with what you skipped. Clean the carbs and throttle bodies. Then go to your set up. Make sure you have the sync & link correct -- including timing. A 1986 had different timing specs than the other V4 loopers. Figure out what carbs are on it and make sure the jets are right. Use the right Champion plugs and 87 octane fuel.<br /><br />Set it up to 6000 with an average load. Dont lug it. You say you never touched the timing during the rebuild. But you did. Removing the top bearing cap means you have to recheck the timing. The top cap has the stop in it. Besides, you dont know what it was to start with.<br /><br />Start with the basics. Youll get it figured out.

Re: Fuel Economy

Awesome. Thanks for the info I was looking for. When i clean the carbs, since they are plastic, will they be affected by the carb cleaner if i soak them? Obviously oil and gasoline don't affect them but what about the other chemicals? Thanks.