OMC/Volvo Penta Planing issues?

[bajaunderground]

Fellow iboaters...

Splashed the boat for the first time this year today and had a few issues (really only one).

After getting out of the no wake area, hit the throttle and the boat wouldn't plane. I had my step-dad in the passenger seat...so, I had him relocate to the bow area, it then planed; however, the performance was less than stellar (couldn't get the RPM's above ~3,700)! Trimmed up/down, a little change, but nothing major. My WOT is between 4,200-4,600 and I have the 1:1.66 out-drive with a 19P prop. Boat starts and idles very well!

I did have the hydrofoil on the re-splash (which I removed and maybe made some sense?)

I'm not expecting the rocket ship I had with the Baja, but I did expect some decent performance. My initial thinking is the 19P is too aggressive for this set-up at this elevation(4,300'); however, it's what the manufacture recommends and I cannot believe that the PO's ran the boat for 8 years with this kinda performance?

So, here's my thoughts on what I need to do...

1) Rebuild carburetor-I did notice an excessive amount of carbon on the back of the boat after running today? The fuel is old; however, I added 6 gallons of new today?

2) Replace fuel filter

3) re-install the Hydrofoil

4) Purchase a 17P prop...assuming the above doesn't yield better performance?

Thoughts?

Thanks in Advance!

~Brett

 

[alldodge]

Re: OMC/Volvo Penta Planing issues?

Fellow iboaters...

Splashed the boat for the first time this year today and had a few issues (really only one).

After getting out of the no wake area, hit the throttle and the boat wouldn't plane. I had my step-dad in the passenger seat...so, I had him relocate to the bow area, it then planed; however, the performance was less than stellar (couldn't get the RPM's above ~3,700)! Trimmed up/down, a little change, but nothing major. My WOT is between 4,200-4,600 and I have the 1:1.66 out-drive with a 19P prop. Boat starts and idles very well!

I did have the hydrofoil on the re-splash (which I removed and maybe made some sense?)

I'm not expecting the rocket ship I had with the Baja, but I did expect some decent performance. My initial thinking is the 19P is too aggressive for this set-up at this elevation(4,300'); however, it's what the manufacture recommends and I cannot believe that the PO's ran the boat for 8 years with this kinda performance?

So, here's my thoughts on what I need to do...

1) Rebuild carburetor-I did notice an excessive amount of carbon on the back of the boat after running today? The fuel is old; however, I added 6 gallons of new today?

2) Replace fuel filter

3) re-install the Hydrofoil

4) Purchase a 17P prop...assuming the above doesn't yield better performance?

Thoughts?

Thanks in Advance!

~Brett

Hi ya Brett, question: Is the issue your having the first time the boat has done this and has always done better, or is this the first time you have ever driven the boat? Just a bit more info would help

 

[MikDee]

Re: OMC/Volvo Penta Planing issues?

The hydrofoil will help you plane off faster then a prop change IMO. If you can attain the proper rpm with the 19" pitch prop, why change? If you will be running heavier most of the time, then I'd recommend the 17" pitch.

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

Hi ya Brett, question: Is the issue your having the first time the boat has done this and has always done better, or is this the first time you have ever driven the boat? Just a bit more info would help

AllDodge: This is the 2nd time I had in the water. The first was back in October before the interior and I was by myself...did not notice any planing issues; however, much less weight as the interior was out (all) and I never tried max RPM. I cannot say whether the boat has always done this as I rebuilt/replaced the motor?

The hydrofoil will help you plane off faster then a prop change IMO. If you can attain the proper rpm with the 19" pitch prop, why change? If you will be running heavier most of the time, then I'd recommend the 17" pitch.

I figure maybe 4-6 people? I'm gonna put the hydrofoil back on, but I'm still not achieving my max WOT (4,200-4,600rpms)

~brett

 

[alldodge]

Re: OMC/Volvo Penta Planing issues?

AllDodge: This is the 2nd time I had in the water. The first was back in October before the interior and I was by myself...did not notice any planing issues; however, much less weight as the interior was out (all) and I never tried max RPM. I cannot say whether the boat has always done this as I rebuilt/replaced the motor?

I figure maybe 4-6 people? I'm gonna put the hydrofoil back on, but I'm still not achieving my max WOT (4,200-4,600rpms)

~brett

So long as everything else is working fine:
Compression, fuel, timing, hull bottom, and a few others

and your not reaching WOT (42-4600) then by changing to a 17 pitch should increase your WOT by about 4-600 rpm. This increase should bring you out of the hole quicker and get your rpm up where it should be.

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

So long as everything else is working fine:
Compression, fuel, timing, hull bottom, and a few others

and your not reaching WOT (42-4600) then by changing to a 17 pitch should increase your WOT by about 4-600 rpm. This increase should bring you out of the hole quicker and get your rpm up where it should be.

Yeah, that's my thoughts too...but, I still am having a hard time believing the PO lived with this performance? Do you think old gas could cause low performance?

I'll check compression if all else fails, new lower end and new head gaskets...could be a valve issue, but doubtful?

 

[alldodge]

Re: OMC/Volvo Penta Planing issues?

Yeah, that's my thoughts too...but, I still am having a hard time believing the PO lived with this performance? Do you think old gas could cause low performance?

I'll check compression if all else fails, new lower end and new head gaskets...could be a valve issue, but doubtful?

Sometimes you never know what some folks are thinking. I've found guys which switched to a higher pitch prop just on the thought that turning less RPMs would save gas. As we know they where probably using more but you could not tell the guy anything. Same issue comes up with folks thinking that higher octane full gets more HP and gas mileage then low octane fuel in a regular compression engine.

Old gas would cause problems but most real old gas causes real bad issues. Take a smell of the gas, if it smells bad pump it out. If the gas smells like gas it's probably fine

 

[captmello]

Re: OMC/Volvo Penta Planing issues?

Something doesn't sound right to me. You've got an 18' boat with a V8. You should have no problem planing out with a 19" prop. I would check the items mentioned by all dodge, comp, ignition timing etc. Did you say you rebuilt the motor and this was the first time out running it?

 

[MikDee]

Re: OMC/Volvo Penta Planing issues?

Fellow iboaters... My WOT is between 4,200-4,600 and I have the 1:1.66 out-drive with a 19P prop. Boat starts and idles very well!

I did have the hydrofoil on the re-splash (which I removed and maybe made some sense?)

I'm not expecting the rocket ship I had with the Baja, but I did expect some decent performance. My initial thinking is the 19P is too aggressive for this set-up at this elevation(4,300'); however, it's what the manufacture recommends and I cannot believe that the PO's ran the boat for 8 years with this kinda performance?

So, here's my thoughts on what I need to do...

1) Rebuild carburetor-I did notice an excessive amount of carbon on the back of the boat after running today? The fuel is old; however, I added 6 gallons of new today?

2) Replace fuel filter

3) re-install the Hydrofoil

4) Purchase a 17P prop...assuming the above doesn't yield better performance?

Thoughts?

Thanks in Advance!

~Brett

His WOT RPM is right with the 19" prop. What he's looking for is to get over the hump to plane. IMO, an 18' boat with a powerful V8 I/O usually is back heavy. He could try a 17" prop, it wouldn't hurt for when the boat is loaded down, but all I think he needs is to put the hydrofoil back on, or try a Doel fin?

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

Just spoke with PO...he says previously he had no issue with 8 people in the boat getting on plane and water skiing behind. He said the boat should run 50mph+ with a 19P prop...so, I've got some adjusting and trouble shooting to do!

Thanks, I'll keep you posted!

~Brett

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

Something doesn't sound right to me. You've got an 18' boat with a V8. You should have no problem planing out with a 19" prop. I would check the items mentioned by all dodge, comp, ignition timing etc. Did you say you rebuilt the motor and this was the first time out running it?

Yes, first time out. I was running the old gas (I know) and the carburetor was not touched. The timing and carburetor rebuild are my first things to tackle!

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

Sometimes you never know what some folks are thinking. I've found guys which switched to a higher pitch prop just on the thought that turning less RPMs would save gas. As we know they where probably using more but you could not tell the guy anything. Same issue comes up with folks thinking that higher octane full gets more HP and gas mileage then low octane fuel in a regular compression engine.

Old gas would cause problems but most real old gas causes real bad issues. Take a smell of the gas, if it smells bad pump it out. If the gas smells like gas it's probably fine

The gas actually smelled fine...like gas, not turpentine!

 

[MikDee]

Re: OMC/Volvo Penta Planing issues?

Yrs ago, I had an 18' Wellcraft airslot bowrider, with an 888 Mercruiser (302 ford 2bbl) 188hp. Someone put long pipes on it for thru hull exhaust at both corners, at the waters edge. It sounded sweet, & went nice, But it must have been a bit back heavy, even with twin side gas tanks, just in front of the driver. I believe I had a 19" pitch prop on it. With me, and, or my girlfiend, that boat would rise, bow up, and stay there until I hit 3k RPM! Then plane off and go about 40mph fully trimmed out. I don't know if the Ford V8's are heavier then Chevys? But after awhile I got tired of this! This was before the Doel fin came out, so I went to the marine store, & bought a cheap pair of semi-round rigid plastic trim tabs, and put them on. What a difference, the boat jumped up on plane by 2500RPM, and gained 2mph! Yes, it would do 42mph now! I guess they discontinued those plastic trim tabs, because I can't seem to find them anywhere now but, I believe a Doel fin would work better even better nowadays, as there's no drag like trim tabs.

 

[jerryjerry05]

Re: OMC/Volvo Penta Planing issues?

Need more info.
5.0FL??? More letters?
They made 10 different FL models.
Most come with a 2bbl Holly
Volvo Penta SX is the drive.
First do a compression test.Post your results.
Then change the fuel filters.
3600 is way low.
Maybe a bad spark plug or a wire loose?
Check the coil. After the motor gets up to temp.It shouldn't be too hot to touch.
The Dolefin and Hydrofoils, they actually slow a boat down.
If they really helped performance the factory would install them.
They do help in planning at a lower speed,that's about all.

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

Need more info.
5.0FL??? More letters? That's the motor designation the model # is 502APNCA ( It's 1996, only FL model offered that year according all my literature)
They made 10 different FL models.
Most come with a 2bbl Holly It is the 2bbl
Volvo Penta SX is the drive.
First do a compression test.Post your results.The motor was recently rebuilt by me and I set timing by ear/feel, I will check compression as a last resort as I'm confident it's something else, plus because it's a FORD I have to remove exhaust manifolds to get clear access to the plugs P.I.T.A.
Then change the fuel filters.This will get done as it needs it anyway!
3600 is way low.
Maybe a bad spark plug or a wire loose?I will double check and replace as needed, plugs are brand new
Check the coil. After the motor gets up to temp.It shouldn't be too hot to touch.I can hold my hands on both risers while it's running, no overheat issues as far as I can tell...the temp gauge stays between 140˚-175˚F
The Dolefin and Hydrofoils, they actually slow a boat down.
If they really helped performance the factory would install them.
They do help in planning at a lower speed,that's about all.Planing is/was my first concern; however, my gut tells me once I figure out the rpm issues, my planing issue will fall in line.

I much appreciate everyone's input as most of you will forget more than I'll ever know! I'm fairly certain it's an adjustment issue as since I replaced motor it has less than 1 hours one her. First time out it was just me, without interior (~300lbs). This was technically my re-splash as I haven't really spent too much time fine tuning the timing nor carb rebuild...I'll tackle the easy items first, then trouble shoot compression if it's not something out of whack...I will say, she starts and idles very well and other than the carbon build-up on the stern, seems healthy (except for the rpm thingy)

Also, any chance it's a throttle connection issue? Meaning, I cannot open the butterflies all the way? The reason I ask is when I intially re-installed the motor she wouldn't stay idling because the throttle cable was pushing too hard against the linkage, so I adjusted it to a neutral position and it idled fine!?

Thanks,

~Brett

 

[bruceb58]

Re: OMC/Volvo Penta Planing issues?

You never set timing by feel. Use a timing light.

I would definitely check compression. How many hours since the rebuild? The engine could easily idle smooth and have 2 dead cylinders.

You should be able to get the spark plugs out without removing the manifolds. You have to shave down a socket to do it though. DonS had some pictures of this if you search.

 

[captmello]

Re: OMC/Volvo Penta Planing issues?

You never set timing by feel. Use a timing light.

I would definitely check compression. How many hours since the rebuild? The engine could easily idle smooth and have 2 dead cylinders.

You should be able to get the spark plugs out without removing the manifolds. You have to shave down a socket to do it though. DonS had some pictures of this if you search.

+1, I've also simply used an open ended wrench where i couldn't fit my socket. kinda depends on how much room you have. But use a timing light for pete's sake!

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

+1, I've also simply used an open ended wrench where i couldn't fit my socket. kinda depends on how much room you have. But use a timing light for pete's sake!

I will use a timing light...I could have dead cylinders from an electrical standpoint...the rings and gaskets are new...less than 1 hour. The electrical components were reused (distributor, cap, rotor and wires). I will figure it out, just not until tomorrow/next week!!!

Again, thanks for all your input! Sometime it's just nice to just hear other people's input (as opposed to just the voices in my head).

 

[MikDee]

Re: OMC/Volvo Penta Planing issues?

Timing by ear? I only do that to get an engine running, then out comes the timing light.

 

[bajaunderground]

Re: OMC/Volvo Penta Planing issues?

I've got a friend who rebuilds cars for a hobby (retired fire chief), he said he always sets his timing by ear...that being said, he might have meant initially? :facepalm:

I bet money he has a timing light? Whatever the case, That's the plan for tomorrow!