motor lugging?

[phatmanmike]

hello<br />1976 merc 1150 inline 6 115hp<br />prop is 13.5 x 21p aluminum<br />boat is 1960 glasspar citation<br />15'11" x 79"<br />dry weight 650 lbs<br />total weight as tested 2100<br />fiberglass deep v in front, almost flat in back<br />air temp 95, water temp 82, 5mph wind, light chop(less than 2 feet)<br /><br />motor runs flawlessly at home! many new parts, tuned, decarbed. good to go<br />boat would not get on plane yesterday! at all.motor kept overheating from engine detonating prematurly, i think it was lugging.the water pump...pumps! good!<br /><br />with that much weight and that much hp, shouldnt it have been able to have gone faster than just a slow idle. could it be my prop was too big to spin effectivly?(thats my thought)<br /><br />when its just me in boat and no gear, boat gets up on plane and hauls major A$$. almost scarey!!<br /><br />i think i need a new prop( i may have figured this myself), but i want your opinions

 

[WillyBWright]

Re: motor lugging?

I'll bet on worn reed blocks. On an inline 6 that old it's almost a Given. With just you in the boat it isn't sitting too low in the water. Add gear and a few passengers and I bet it's sitting considerably lower.<br /><br />Worn reed blocks make starting and idling very difficult. It can be unnoticable on the muffs, but put it in the water and give the exhaust some back pressure and it idles poorly and dies on takeoff or when put into gear. I bet it's not getting enough back pressure to cause a problem if the motor is sitting higher in the water with just you in it. Add weight and sink the motor deeper in the water is where you're having trouble...more exhaust back pressure.

 

[Mod2]

Re: motor lugging?

Mikey....I'm going to move your post over to Merc/Mariner forum. I think you'll get some more opinions there.<br /><br />One thing...just about any engine will run like crazy in the driveway. No back pressure on the cylinders.<br /><br />Hope you find the answer.