2004 2000 Sr3 5.0 carbed help with prop

[Sandrager]

Hey All ,
Dinged up my prop last time out last summer. Little advice want to increase the hole shot. Has the 14.5 x 19 3 blade prop on there now. My tac isn't working and never ran it WOT for that reason last year. It's stuck about 1200 rpm. I unplugged it last night and didn't change nothing, tried the magnet trick and that didn't work. It worked for the other gauges though.

Had the boat loaded last year on the 4tha nd had trouble getting on plane, had 5 people in the boat, towing 2 more plus 2 coolers. Thinking of going to 4 blade 14.5 x 19. I think dropping to 17 would be too low for 5.0 dont want to over rev. I have no reason to go more than 30.

Need to check for 12v at the tac that might be the problem.

thanks
Sand

[jrsick]

Sand, has your tach ever worked? Does it sit at 1200 even when powered off?
I recommend you pull the wiring harness off of the tach and clean all the connectors with a wire brush. If there is a dial on the back of the tach, make sure it is set to "8".
A 17 pitch prop may be just right for you. A four-bladed 17P would work also, but I recommend try 3 bladed prop first.

[mmwjr]

Staying at the same diameter and pitch but adding a blade will go the opposite direction you want. That extra blade is additional load on the engine. Is this a 2 or 4 bbl carb? I agree jrsick go 3 blade 17 pitch.

[shrew]

I would suggest getting the tach fixed, then sizing the propellor with the tach. It's going to be hard to size a new prop if you can't determine if your outside of the max rpm and on which side of the range.

Just my humble opinion.

[Sandrager]

Hey All,

Thank you for replies.

Shrew would totally agree with you but my current prop is damaged so can't. With a 4 blade any chance of lessening life on my drive ?

JR good advice and need to check 12v also

MM, Ya you'r right if I go 4 blade should switch to 17

Thanks much

[mmwjr]

A prop can cause damage if it loads the engine too much. This is why a properly operating tachometer is required.

[shrew]

Originally Posted by Sandrager

Hey All,

Thank you for replies.

Shrew would totally agree with you but my current prop is damaged so can't. With a 4 blade any chance of lessening life on my drive ?

Many props shops will work with you with either loaner props or exchanges until you can get it 'tuned' right. A good place to start is with an undamaged version of the same size and pitch as what you have to get a baseline. Then, once you see where your max rpm is as compared to the target range, you can decide if you want to add a blade, ad/drop pitch, etc.

Just a thought.

[Sandrager]

Hey Guys ,
Had sometime to tinker this weekend. Tried a few things with Tach/Rpm gauge. Tried using light sand paper on contact pins with electrical grease. Verified the tach is getting 12.85-12.98 volts. Also the back light is on just hadn't noticed it before since was in daylight. I tried pushing in setting for engine in back and move all the way left and all the way right and didn't change. Moved it back to 3 since it is a 5.0 8cyc engine. From my understanding when it gets power it should drop to 0 correct. Based on that even if the sensor wire had a bad connection it should still drop to 0 right ? so don't think it is a bad sensor wire. Please let me know your thoughts on sensor wire. Also any other ideas or it is just time to send it in ? At the moment it stayed at 1,500 rpms whether engine key was turned to accessory or not. I did turn engine on ( tach stayed at 1,500rpms) this weekend and got engine up to temp so yeii no cracked blocked (wasn't sure with cold temps we got although was winterized was still nervous, she was purring and holding temp below 175F , no leaks and engine oil looked good no water in it. Start of a great season

Thanks
Sand

[mmwjr]

The tach should read zero when the engine is off. It needs to be repaired or replaced.

[Sandrager]

Hey All ,
thanks Mike. Another questions as long as it is 15 spline. Are props different if they are thru exhaust or not ? I picked the Solas rubex 4 14.5 x 17 and it said in description fits through hole exhaust for merc 5.0. I went back and checked on prop finder and made through I picked for hp range not including thru whole exhaust and same mfg p/n was there on list. Based on that think I can get prop, i had already ordered it at this point and noticed after the fact. think I am ok though.

FYI just going to take it easy with this prop until the rpm gauge comes back from repair. No towing and slow speeds which is fine, wife gets nervous about when I hit 20 hahah

Not sure I can post links here
So got rubex 4 14.5 x 17p - 9513-145-17
hub kit - RBX-102

Thanks
Sand

[mmwjr]

Sand this prop allows you to select different hub kits to fit on different manufacture shafts from I/O to O/B. A lot of props come with a fixed hub that is pressed in so it only fits one size shaft. You have the right kit.