Re: help with outdrive
MH11 says his engine cannot get past 3100rpm with whatever ratio is in the drive, say it really is the 1.98 ratio. If he puts in a 1.5 ratio the problem will get worse.
That size boat with a good running 350 cube engine should be able to stay at or above 19 on the pitch and still get to 4400rpms in my opinion.
Also, the cracked exhaust hoses indicate it has been run hot at some point, maybe it was with the previous engine but maybe with this one. In any event those hoses should have been changed if the cracking is causing exhaust/water leaks on the inside.
If the engine was ran hot then there could be cylinder sealing problems. A compression check is the first thing to do. A new intake and the rest is not justified at this point. Do the compression test with the throttle open so as not to restict the intake stroke.
Backfiring thru the carb? That thing needs a full tuneup including fuel system and carb. The carb needs to back to specs as far as fuel metering, and needs to be operating correctly. Backfiring thru the carb can also come from an intake valve sealing problem.
FIRST ORDER OF BIZ: Do the compression test correctly and report back before doing ANYTHING else to the engine.
Your gear ratio is off!! The 1.98 ratio is killing the motor. Running the data you supplied thru prop calulator (10% slip) the speed is pretty close. The data plugged in at 4600rpm @1.5 ratio pops you back at 45mph.
http://www.byuboyz.com/boats/prop.htm
MH11 says his engine cannot get past 3100rpm with whatever ratio is in the drive, say it really is the 1.98 ratio. If he puts in a 1.5 ratio the problem will get worse.
That size boat with a good running 350 cube engine should be able to stay at or above 19 on the pitch and still get to 4400rpms in my opinion.
Also, the cracked exhaust hoses indicate it has been run hot at some point, maybe it was with the previous engine but maybe with this one. In any event those hoses should have been changed if the cracking is causing exhaust/water leaks on the inside.
If the engine was ran hot then there could be cylinder sealing problems. A compression check is the first thing to do. A new intake and the rest is not justified at this point. Do the compression test with the throttle open so as not to restict the intake stroke.
Backfiring thru the carb? That thing needs a full tuneup including fuel system and carb. The carb needs to back to specs as far as fuel metering, and needs to be operating correctly. Backfiring thru the carb can also come from an intake valve sealing problem.
FIRST ORDER OF BIZ: Do the compression test correctly and report back before doing ANYTHING else to the engine.