What's the difference between.....

[MarkHPCA]

an '86 120 looper and the same year 140 HP? The 120 I believe is a 1.8 Ltr. Do they have the same lower unit ?

 

[jimmbo]

Re: What's the difference between.....

20 hp. Both use a 1800 ml block and both have the V6 gearcase.

 

[Dhadley]

Re: What's the difference between.....

They have the V6 STYLE gearcase but a different ratio than the standard V4 or V6. The basic difference in the motors is in the induction area.

 

[MarkHPCA]

Re: What's the difference between.....

So..... if I wanted to convert my 120 to a 140 what would I need, different carbs, reed blocks ? How about timing? Anything else ? What would be the effect on the reliability?

 

[jimmbo]

Re: What's the difference between.....

Different block, carbs, exhaust tuner, might need a couple of parts on the throttle linkage. Total timing advance should be the same but pickup timing might be different.

 

[phatmanmike]

Re: What's the difference between.....

easiest way to CONVERT your motor to more hp, is to replace the decals with larger ones... sorry, but im serious...you cant just swapp out a carb or sumthing and gain a magic 20hp!

 

[DJ]

Re: What's the difference between.....

I have to agree with the others. OMC did not make it that easy.<br /><br />The 120 was a solid performer on its own.<br /><br />Tune 'r' up and she'll go great. Prop her for her powerband (5500+ rpm-WOT).<br /><br /> Nice engine.

 

[MarkHPCA]

Re: What's the difference between.....

I kind of thought a carb swap was too easy. I can live with what I have for now. Pushes my Hydrostream to 60 MPH with lost of torque.<br /><br />Thanks for the input guys.

 

[Dhadley]

Re: What's the difference between.....

Hydrostream? Now we're getting somewhere. Which model?

 

[MarkHPCA]

Re: What's the difference between.....

Actually it's a Canadian Edition Vista. This was the CE version of the Valero bowrider, V bottom. Same hull as the V-King but a different deck.<br />

 

[Dhadley]

Re: What's the difference between.....

The motor looks kind low. What prop are you running?

 

[MarkHPCA]

Re: What's the difference between.....

I have raised the motor since the picture was taken. I am running 2" below the pad, 5 1/2" setback CMC jackplate, with a 24P Raker at 5500 RPM WOT and getting 60 MPH. I don't think I can get much more with this set-up and limited power, remember this is a bowrider so it is a little heavier than the V-King.

 

[Dhadley]

Re: What's the difference between.....

Are you running the V6 size gearcase?<br /><br />We need to get the R's up.<br /><br />Is the pad flat or concave?

 

[MarkHPCA]

Re: What's the difference between.....

Yes, I believe it is the V6 case. The pad is flat, I re-cored the boat last winter so the pad was well checked then. I can try going higher with the motor but any higher and the water pressure starts to jump around quite a bit as I hits waves etc. At the moment it is faily steady at 29 PSI. How about blocking the top water intake hole on each side? Would this still allow sufficient volume of water to cool the motor?

 

[Dhadley]

Re: What's the difference between.....

OK, thats good and bad as far as the case goes. Bad because the larger case = more drag. Good because V6 style props are way easier to come by.<br /><br />Yes you can fill the top two holes on each side. I like to do it by tapping the hole and screwing in a pipe plug. If you do it with epoxy you stand the chance of getting epoxy in the water passage.<br /><br />There is actually enough room at the bottom to add another hole. On one side of the gearcase there is a very small hole that is a drain at the bottom of that chamber.<br /><br />Good catch on the water pressure. It may be time to think about a low water pick up. Lets try the other but start thinking about it.

 

[MarkHPCA]

Re: What's the difference between.....

Thanks Dhadley for the suggestions/help so far. How can I tell if it is a V6 or V4 gear case? The one I have is 4" diameter.<br /><br /> I will try plugging the top holes and raising the motor some more to see how it goes.

 

[Dhadley]

Re: What's the difference between.....

Are the threads for the prop nut fine or course?

 

[MarkHPCA]

Re: What's the difference between.....

The outside diameter of the threaded part is 5/8" and there are about 11 TPI, so I guess this is course ? If so is it a V6 or V4 case ?

 

[Dhadley]

Re: What's the difference between.....

Fine threads are a V6 style and course is a V4 style. <br /><br />Also if it were a V6 style the Raker would be a 14 1/2" diameter. The V4 Raker is 13 1/2" diameter.

 

[MarkHPCA]

Re: What's the difference between.....

The prop is 13 1/2" so I guess it's a V4 case, as you say at least this is less drag. I'll try the hole plugging and see what happens this weekend.