Prop pitch for heavy load

jph190 · **Posted:** Fri Aug 07, 2015 7:37 am

More power, eh? Guess I'll just swap out the engine real quick!

4 blade sounds good, should diameter and pitch be similar to 3 blade?

rpengr · **Posted:** Fri Aug 07, 2015 8:17 am

I still think you have a carburetor problem that needs to be addressed before worrying about the prop. The engine should not "bog down" above a certain throttle setting even if it is overloaded/overpropped. That is a symptom of fuel starvation.

LouC · **Posted:** Fri Aug 07, 2015 10:18 am

Given the speed you quoted it sounds like the boats not even getting on plane. You replaced the carb so it sounds like you had a fuel problem prior to this. I'd go back and check the rest of the fuel system, fuel filter, fuel vent, anti siphon valve, clean out the flame arrestor if its dirty, etc.
However with 7 people in the boat, if 3 are not in the bow, the boat will struggle to get it on plane with the V6 I'd think. My boat's rated for 10 people I can't even imagine trying to plane it with that load.

rchamberlin · **Posted:** Fri Aug 07, 2015 10:36 am

I have a 2000 190 Horizon with the 4.3GL, and when I got it, it had a 3-blade aluminum 14.3x21 prop. The fast facts from the FW website said the factory prop was 14.3x23. While it was ok, it was not great with four adults and four kids in there. Over the winter I bought a 14.3x21 4-blade aluminum one, and it's like a different boat now. It jumps out of the water with the same group on the boat. The RPMs are right on with it as well. This is the one I bought. Pretty inexpensive for the amount of performance improvement I gained.

I also had a bogging issue, although mine would happen right after I took off. It'd start to go fast, then bog down, then go fast again. I bought a rebuild kit for my carb, but I'm scared to take it apart for fear of not getting it back together again. I just used some carb cleaner and the bogging issue went away, at least for now.

jph190 · **Posted:** Mon Aug 10, 2015 4:24 pm

Could a kinked fuel pump to carb hose explain this?

LouC · **Posted:** Mon Aug 10, 2015 5:18 pm

Any restriction in the fuel system could.

meinmelb · **Posted:** Thu Aug 13, 2015 3:54 am

Mate I have a H190 with a Merc 4.3mpi. I run a 19P high 5 stainless that has been vented, polished and balanced, just to get the fat barge out the water and on the plane with 8 people. It is a great prop and made a world of difference to the boat. I also have since installed Smart-Tabs to keep its arse on the plane at kids skiing speeds, but they also help get the boat on the plane.

Bottom line I think anything above a 21P on your set up will not pull the skin off a custard. A 21P might be fine for 2 or 3 people and a full tank of fuel. Load up with 8 or so and a 21P will eventually get you there but a 19P will solve your hole shot.

As a rule of thumb the more blades on the prop the more surface area for a prop to grip so more power is transferred to the water for better pull out / hole shot. But the more blades the more drag at higher speed so lower top end.

As for a carb.. sorry cant help I deliberately opted for fuel injection as all the carbs I have had in boats gave me problems.

jph190 · **Posted:** Wed Aug 19, 2015 3:12 pm

So I tried the 14.5 x 19 and the boat got out of the water like a champ. However... Couldn't get above a little under 30 MPH at about 3200 RPM. That is a very approximate recollection but it was nowhere near redline or expected top speed. Seems like fuel starvation is a good possibility. Increasing throttle at that speed caused the engine to stall. The fuel pump to carb line appears rather kinked so I'm trying to figure out how to unlink it before this weekend and test again. Also the spark plugs are fouled.

rpengr · **Posted:** Thu Aug 20, 2015 7:24 am

jph190 wrote:

So I tried the 14.5 x 19 and the boat got out of the water like a champ. However... Couldn't get above a little under 30 MPH at about 3200 RPM. That is a very approximate recollection but it was nowhere near redline or expected top speed. Seems like fuel starvation is a good possibility. Increasing throttle at that speed caused the engine to stall. The fuel pump to carb line appears rather linked so I'm trying to figure out how to unlink it before this weekend and test again. Also the spark plugs are fouled.

While the kinked line should be corrected, it does not sound like your problem. This is because your problem seems to happen above a specific throttle setting. If it was the kinked line, the carburetor bowl would run low after several seconds at the higher throttle, but not right away.

It still sounds like improper jetting or clogged fuel or air passageway in the carburetor. When you say your spark plugs are fouled, do you mean black buildup? That would be too much fuel.

If possible, post pictures of the plugs. Also send this information to the company where you got this carburetor. They should be helping you out with this issue, or exchange the carb.

jph190 · **Posted:** Sun Aug 23, 2015 2:12 pm

Here are some plug pics:

https://drive.google.com/file/d/0B9y1jX ... cslist_api

https://drive.google.com/file/d/0B9y1jX ... cslist_api

https://drive.google.com/file/d/0B9y1jX ... cslist_api

https://drive.google.com/file/d/0B9y1jX ... cslist_api

The engine is rather wobbly at idle. I'm wondering if the distributor or cables could be having problems.

GottWhat · **Posted:** Sun Aug 23, 2015 7:45 pm

The fact that one of them does not look like the others means one of the cylinders is not firing like the others.

NOLV4V8 · **Posted:** Mon Aug 24, 2015 7:45 am

another question, did you replace the Plugs / Cap / Rotor / Coil / Spark Plug Wires? Also did you fresh gas?

jph190 · **Posted:** Mon Aug 24, 2015 4:22 pm

I have replaced the fouled plugs (this didn't help) but not the distributor or wires.

I called the carb place and they basically said I could send it in and they could look at it. This would be rather inconvenient so I'd like to be sure it's the carb if going down that path.

GottWhat · **Posted:** Mon Aug 24, 2015 4:49 pm

Check the cap & rotor.

LouC · **Posted:** Mon Aug 24, 2015 5:08 pm

3/4 of them are showing either an extremely rich mixture, or weak spark.
Make sure the plug wires do not have too much resistance.
Go over the whole ignition system including cap, rotor and coil.
Check the flame arrestor, is it all clogged with wear particles from the belts (common) due to rusty pulleys?
Carb could be set too rich. Choke opening all the way?
Your plugs should be a light tan/grey color. Those are way too dark.

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Prop pitch for heavy load

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