can any one help me to understand

[bruceb58]

Re: can any one help me to understand

You need to multiply the number you get by 10. Says so right on the meter at the bottom. You can do a quick test and rev the motor up to 3000RPM on the muff if you have enough water flow.

 

[bruceb58]

Re: can any one help me to understand

The prop you have on there looks quite worn and appears to be a "big ear" pusher prop for applications like pontoon boats. With a stern heavy boat like yours I'd go with a high rake 4 blade prop in the 21" pitch range. Other I'm sure will have other recommendations.

That prop looks like a normal prop for that boat. Personally, I would stick with that style prop. What we don't know is if that prop was ever repaired and if is, the pitch was set correctly. I bought a set of dup props once and sent them to my repair guy and the pitch on the blades were different from each other.

The prop actually looks like it is in very good condition. I was expecting dings on the prop edges.

I am amazed he has the 1.81:1 ratio.

here is that prop on iboats
http://boatpropellers.iboats.com/Me...A1912X_Propeller/769/19574/?*******=810958676

I think I would be going out and figure out what the correct RPM is before buying a prop. I would just buy a 3 blade prop.

 

[trendsetter240]

Re: can any one help me to understand

That's the old style pusher prop. If you look closely at the edges all the cupping is either worn off or wasn't there in the first place. I'd think you want something with high rake and good cupping to lift that heavy boat up and grip the water well.

I've run lots of 3-blades and 4-blades and truly the difference is minimal on most boats. But they cost the same and if you are looking for mid range cruising and fuel economy the 4 blades perform better.

 

[trendsetter240]

Re: can any one help me to understand

You need to multiply the number you get by 10. Says so right on the meter at the bottom. You can do a quick test and rev the motor up to 3000RPM on the muff if you have enough water flow.

Good catch! So what..now the tach is reading low? Definitely take it out for a test with the shop tach to find out what's going on.

 

[mannydvk11]

Re: can any one help me to understand

You need to multiply the number you get by 10. Says so right on the meter at the bottom. You can do a quick test and rev the motor up to 3000RPM on the muff if you have enough water flow.

bruce58 on the instruction manual say multiply by the number of cylinders and i did tested with the muffs on on hi RPMs the reading was correct every time btw i also found the gnd wire the nut in the back was a bit loose before i found that the tach was a bit jumpy after i corect that problem the tach acted normal

 

[mannydvk11]

Re: can any one help me to understand

That prop looks like a normal prop for that boat. Personally, I would stick with that style prop. What we don't know is if that prop was ever repaired and if is, the pitch was set correctly. I bought a set of dup props once and sent them to my repair guy and the pitch on the blades were different from each other.

The prop actually looks like it is in very good condition. I was expecting dings on the prop edges.

I am amazed he has the 1.81:1 ratio.

here is that prop on iboats
Quicksilver Black Diamond + Flo-Torq Hub Aluminum Boat Propeller #QA1912X for Mercruiser Sterndrive Alpha One 5.7L 210 - 320 HP - iboats

I think I would be going out and figure out what the correct RPM is before buying a prop. I would just buy a 3 blade prop.

I am amazed he has the 1.81:1 ratio? is that good or bad

 

[mannydvk11]

Re: can any one help me to understand

That's the old style pusher prop. If you look closely at the edges all the cupping is either worn off or wasn't there in the first place. I'd think you want something with high rake and good cupping to lift that heavy boat up and grip the water well.

I've run lots of 3-blades and 4-blades and truly the difference is minimal on most boats. But they cost the same and if you are looking for mid range cruising and fuel economy the 4 blades perform better.

i just called my friend who sold me the boat and he told me he change the prop ones and he just put a replacement one witch it was the first one he try on not the one for the boat he don't remember what was the original on it but he remembers that one is not the same

 

[bruceb58]

Re: can any one help me to understand

bruce58 on the instruction manual say multiply by the number of cylinders

It doesn't say that at all. That is why you put the selector at 8.

read the bottom of the tach

Here is the manual:
http://manuals.harborfreight.com/manuals/95000-95999/95670.pdf

Even says resolution is 1x10 RPM in the manual.

What does it say at the arrow?

 

[mannydvk11]

Re: can any one help me to understand

this is not on that is another extra page on the manual

 

[bruceb58]

Re: can any one help me to understand

I am amazed he has the 1.81:1 ratio? is that good or bad

Its only different than what usually come with a 5.7.

 

[bruceb58]

Re: can any one help me to understand

Are you clamping it on a spark plug wire from the distributor or from the wire from the coil to the distributor?

 

[mannydvk11]

Re: can any one help me to understand

from the coil to the distributor

 

[bruceb58]

Re: can any one help me to understand

from the coil

Then you only need to multiply by 10.

Read your instructions again. It says to multiply by the number of cylinders if you put it on a spark plug. If you put it on the coil wire, you don't multiply. Those instructions are for the pickup sensor, not the meter.

 

[mannydvk11]

Re: can any one help me to understand

ok lets see 67X10 =670 idle and with the boat tach at 1000 the shop tach show 137 X 10 = 1370 at 3000 rpm show 370 X 10= 3700 am guessing the boat tach is wrong

 

[bruceb58]

Re: can any one help me to understand

Interesting that the shop tach shows higher but who knows what will happen at the high end when you were measuring 6000.

 

[mannydvk11]

Re: can any one help me to understand

I will try to get out ASAP but in the mean time the prop I have am guessing is not the Rigth one so I will order a new one let's say with the Rigth rpms what will be a good size and I will go with the 4 prop

 

[bruceb58]

Re: can any one help me to understand

Don't order the prop until you go out and figure out what RPM you are really running at. Don't go over 4500 RPM.

 

[mannydvk11]

Re: can any one help me to understand

I found this I will check all the connections and try to see if my tach needs calibration

Troubleshooting Teleflex Tachometer Gauges

 

[mannydvk11]

Re: can any one help me to understand

ok guys i tested the tach and at 380 on the shop tach the boat tach was at 5000 rpm i try many times with the same results so before i get the prop what type of tach will be good for my boat

 

[mannydvk11]

Re: can any one help me to understand

Don't order the prop until you go out and figure out what RPM you are really running at. Don't go over 4500 RPM.

according to the shop tach i can only go 5000 rpms no more then that