bad prop limit engine rpm?

[jamesdad]

i have a 5.0 vp that will not make any power under load. it wont plane or go more then 5mph. the engine is fine in neutrel but in gear its no good. you can hear the engine trying to come up in rpm but it just wont. could my prop thats pretty shot do this? thanks james

 

[QC]

Re: bad prop limit engine rpm?

It would have to be so bad it wouldn't even look like a propeller if it is limiting it 5MPH . . . With the exception of a spun hub which it doesn't sound like from your description, a prop really couldn't limit a 5.0 to 5 MPH unless you found a way to get the prop from the Queen Mary on there Is the engine revving up while in gear? What's the max RPM you get at that whopping 5 MPH? .

 

[180shabah]

Re: bad prop limit engine rpm?

Don't rev it in neutral - it's irrelevent and destructive.

We need to know, IN GEAR, is the engine reving high with very little forward thrust, or will it just not spin any faster than idle?

 

[steelespike]

Re: bad prop limit engine rpm?

Check at the carb to see if it is opening all the way.Is this a sudden developement?
Very carefully spray a little fuel in the carb at speed.Check that it is running on all cylinders.

 

[jamesdad]

Re: bad prop limit engine rpm?

it will not pass around 2200 rpm in gear and you can hear it trying to make the rpms. and the carb is definetly opening up all the way.

 

[QC]

Re: bad prop limit engine rpm?

OK, we still need more info. You get 2200 rpm and the boat will not exceed 5MPH, right? I could believe 12 MPH and 2200 RPM, but I am struggling with 5 MPH, and it is why I am not thinking engine problem yet. Has it ever exceeded 5 MPH and 2200 RPM since you owned it? What make, model, size and weight is this boat? How bad is the prop? Picture? Trailered? Slipped? What is the condition of the bottom?

 

[45Auto]

Re: bad prop limit engine rpm?

When's the last time it had a full tune-up (plugs, cap, rotor, timing set) and compression check?

 

[jamesdad]

Re: bad prop limit engine rpm?

ok maybe 5 is a little slow but it will raise the bow some then just hold it so i need to gps it. the boat is new to me with a replaced 5.0 motor i just checked the prop and it is a 15x19 michigan missing a 1inch by 6 inch peice of one edge on the outer blade (NOT GOOD) although nothing looks bent it has the elephant ears. i have no idea on the tune up although cap and roter seem new. i looked online and it says a 25 ft boat like mine should be running a 15x17 or 16x16 can this also be a factor? james

 

[jamesdad]

Re: bad prop limit engine rpm?

it is a 24.5 bayliner slipped and the bottom is clean. its a 1986

 

[180shabah]

Re: bad prop limit engine rpm?

big boat, small engine, damaged prop of (possibly) incorrect pitch, could definately make impossible to get on plane. One more variable - what is the gear ratio in the drive?

 

[QC]

Re: bad prop limit engine rpm?

All makes sense now . . . I agree with 180. I am thinking a 15 or 17 inch pitch, trim tabs, remove as much weight as possible, and I think you kinda got what you got. What are you doing with the trim?

 

[jamesdad]

Re: bad prop limit engine rpm?

i have trim tabs leave them center. the trim/tilt i have threee holes out. also a freind says he has a 15x17 prop for me but it is rh where mine is lh. he said i can just reverse the cable on the volvo out drive and it would work. is he nuts? thanks james

 

[QC]

Re: bad prop limit engine rpm?

Bring the trim in, use your tabs, and see what happens . . .

I don't know on the Volvo shift question, so post that in the I/O section.