140 johnson prop question????

[mbecke2]

I have a 17 foot chris craft ski boat just recently repowered with 140 johnson 1988. Runs like a top. Anyway the motor I took off is a 110 johnson. I noticed with the 140 it was actually slower (about 36mph) so I checked the prop. It had a 15 pitch, so I took the prop off my 110 and tried it on the 140, which was a 19 pitch, and bam!! She went about 43mph. So I bought a 23 pitch thinkin I would go about 48mph, and I tried it out today and only got 45mph. So i was a bit dissapointed... Problem is this-- MY TACH IS BROKE!! So I have no idea on rpms. Well with the original 110 she went about 40-41mph and now I go maybe 43-44mph. Is there anything else I can do?? Will raising the motor a couple holes on transom help?? Should I try a 21 pitch?? Or should I be happy with 44mph?? Thanks for reply!

 

[Gary H NC]

Re: 140 johnson prop question????

I think a 23 pitch is over doing it on that setup..
A 19 to 21 should get you closer to the correct wide open throttle RPM..
Just guessing without a tach though..

 

[canman]

Re: 140 johnson prop question????

I think a 23 pitch is over doing it on that setup..
A 19 to 21 should get you closer to the correct wide open throttle RPM..
Just guessing without a tach though..

i would try a 17 pitch. thats what i run on my 140 .wide open it turns up 6000rpm .

 

[mbecke2]

Re: 140 johnson prop question????

How fast do you go?? I was goin about 42mph with a 19 pitch. Think I was around 5500 but thats a guess.

 

[canman]

Re: 140 johnson prop question????

How fast do you go?? I was goin about 42mph with a 19 pitch. Think I was around 5500 but thats a guess.

the boat runs 58 mph . and thats going by the police radar gun . the boat is a 16 foot larson senza bowrider .

 

[Tacklewasher]

Re: 140 johnson prop question????

1. Fix the tach. Otherwise you are just guessing at set up and pitch.

2. I would try to raise the motor. I've got mine (evin 115) as high as it goes and rarely vent. Picked up a couple mph doing it.

3. I run a 15p on mine. I have an 18' Starcraft so probably lighter than your setup. I would think you need 17 or 19.

4. Fix the tach. Otherwise you are just guessing at set up and pitch.


Canam. Something is funny with your numbers.

Prop pitch - 17p
RPM - 6,000
Gear ratio - 2:1 (that's what my 115 Evin is and I'm sure the 140 is the same)
Theo speed - 48mph

Can't see how you hit 58 with the setup.

 

[canman]

Re: 140 johnson prop question????

1. Fix the tach. Otherwise you are just guessing at set up and pitch.

2. I would try to raise the motor. I've got mine (evin 115) as high as it goes and rarely vent. Picked up a couple mph doing it.

3. I run a 15p on mine. I have an 18' Starcraft so probably lighter than your setup. I would think you need 17 or 19.

4. Fix the tach. Otherwise you are just guessing at set up and pitch.


Canam. Something is funny with your numbers.

Prop pitch - 17p
RPM - 6,000
Gear ratio - 2:1 (that's what my 115 Evin is and I'm sure the 140 is the same)
Theo speed - 48mph

Can't see how you hit 58 with the setup.

i dont have a speedo just a tack and a water temp gauge in my boat i am just going by what the marine patrol told me .