dont want to damage my drive please help

i have a 1982 larson dc 25 foot. it has the omc stringer drive which i understand is old. i bought this boat over the winter with a 305 chevy engine however after learning the block was cracked i had to replace the motor. i picked up a marine 350 which was supposed to run great. after using it once i learned the motor had a hard knock and had to be replaced yet again. this time the block however was good. when i went to rebuild the motor i learned the motor was a 4 bolt main and the cylindar walls were bored out 30 over. ( my father is the mechanic not me so if i screw up the terms i apoligize). anyway this motor is prob pushing out somewhere in the 300 horsepower range. i have been told many times that the omc stringer can only handle 260 horse max. too late now the motor is in and i have been crusing for the last couple weeks with no issues.... right now my boat will do about 20 mph at 2800 rpms. and i accelerate slowly cause i am trying to pamper the drive. how fast or how many rpm's can i push this boat to without causing the drive to overwork and break. any suggestions would be great.

Re: dont want to damage my drive please help

You can run the engine at the reccomended RPM range. It is not the RPMs that will kill the drive but the max torque that will kill it. Just accelerate smoothly and you will be easier on the drive that way.

Re: dont want to damage my drive please help

great thanks.. what do you reccomend i run the rpm's at for a crusing.....

Re: dont want to damage my drive please help

WOT should be in the 4200-4500 RPM range or so.

What you cruise at is kinda up to you depending on the size of your boat, fuel mileage etc. Where you are really going to strain the stern drive is when you are trying to come up onto plane where you have the most load. Once you are on plane, the load is reduced so you adjust your cruise speed for fuel usage, sea conditions...etc.

Do you have trim tabs on your boat? They will help you get up on plane with less strain on your engine/drive.

Re: dont want to damage my drive please help

yes i do have trim tabs and i use them to help me get on a plain. i have been cruising at about 2800 rpms so far. i have maxed out at about 3300 however if i push it to hard the boat seems to slow down like its not getting enough fuel. as soon as i pull the throttle back a little she pics right back up. i wonder if this is some kinda filter problem.

Re: dont want to damage my drive please help

angie1015 said:

i learned the motor was a 4 bolt main and the cylindar walls were bored out 30 over. this motor is prob pushing out somewhere in the 300 horsepower range.

Click to expand...

.030" over ads no measurable HP increase.
And, NO, it's not putting out 300HP because you aren't revving it to 6,500 RPM.
That's where these engines put out 300 HP.
At 4600 RPM, it's putting out approx. 250HP and your OMC drive will not suffer from that.
Just like every other drive, the OMC drives fail due to abuse and lack of maintenance, not too much HP.
Cruising around with a gearcase full of water instead of oil is the most common failure of OMC stringer drives.

Re: dont want to damage my drive please help

thanks for all the great advice. is there a way to check the oil in the gearcase while the boat is in the water??

Re: dont want to damage my drive please help

It's also not the HP that you are worried about...it is the peak torque that you are worried about.

There all all sorts of things that can prevent you from getting to full RPM.

1)Wrong prop
2)Fuel Filter
3)Fuel Pump
4)Carb
5)Distributor not getting full advance
6)...

Re: dont want to damage my drive please help

You need the drive out of the water to check it.

Sorry!