89' 120 and a 140 hp johnson power difference?

[Bob Gilvary]

I've looked and compared part numbers on carb parts and all are identical on these two engines. except the intermediate jet. #50 on the 120's and #54 on the 140's.

I then went to the power packs. Both use the same packs.

Question is; Is the power difference only in that intermediate jet, or is there something else that boosts the 120, to a 140?

 

[tashasdaddy]

Re: 89' 120 and a 140 hp johnson power difference?

the negliable difference at 120 vs 140, is not worth screwing up a motor to find out.

 

[kbait]

Re: 89' 120 and a 140 hp johnson power difference?

Check part numbers of powerhead parts here: http://epc.brp.com/SiteMods/BRP_Public/BRP_Public_Login.aspx?ReturnUrl=/Index.aspx
There's got to be a difference in cyl head, pistons(rods), exhaust, intake, reeds.. Something will be different.

 

[nymack66]

Re: 89' 120 and a 140 hp johnson power difference?

I've looked and compared part numbers on carb parts and all are identical on these two engines. except the intermediate jet. #50 on the 120's and #54 on the 140's.

I then went to the power packs. Both use the same packs.

Question is; Is the power difference only in that intermediate jet, or is there something else that boosts the 120, to a 140?

The answer is yes, the carbs on the 140 has a larger venturi, If you look at the butterflies on your 120 it has 2 screws, on the 140 its 3 screws. Quick visual of the difference...Lots of folks swap the carbs and throttle body's out, re-jetted and presto 140 hp...

 

[daselbee]

Re: 89' 120 and a 140 hp johnson power difference?

The answer is yes, the carbs on the 140 has a larger venturi, If you look at the butterflies on your 120 it has 2 screws, on the 140 its 3 screws. Quick visual of the difference...Lots of folks swap the carbs and throttle body's out, re-jetted and presto 140 hp...

But Andrew, I just looked the parts up...and the 120 and the 140 use the same upper carb body, as well as the same throttle plate, just like the original poster says.

Look 'em up.

 

[dazk14]

Re: 89' 120 and a 140 hp johnson power difference?

Bob,

It's a fair question, but Tasha is giving you good advice.

The extra power is made by at least the difference in intake manifolds and reed assemblies and it's the hidden "Gotcha's" that will keep you up nights (exhaust tuning,etc.)

Unless you have access to cheap used 140HP parts and someone that has done many of this type of conversions it's rarely worth the headache - although I have converted some motors over the years.

It's also not uncommon for the higher HP (same block) to idle worse and have less low end torque.

If you haven't already, the "right" stainless prop will often give you equal or better overall performance.

Hope this helps!

 

[Bob Gilvary]

Re: 89' 120 and a 140 hp johnson power difference?

I would've thought there would be a big difference or at least a difference in the carbs, other than just a jet size in only the carbs. The 4 jets would cost about 20.00 shipped in.

I'm not about to change anything, I sold the engine.

It was an 89' 120, previously owned by the city of Nashville. When I got it from the previous owner it was missing a starter, solenoid, and a couple of hoses, and needed a good clean up. Ugly engine, 250.00

I took a chance and invested in a used starter and solenoid, 95.00. Cranked it to check spark and compression. Compression was 135 on all cylinders, and spark on #2 only. Yup, it now needed a power pack, 115.00 from Iboats.

Carb kits, add fuel, and it busted off and roared like a lion. It pumps water very well, but a new pump will be installed by me before it goes into service.

I'm still curious about the hp difference, and will check on internal parts.

Thanks all for the input.

 

[Bob Gilvary]

Re: 89' 120 and a 140 hp johnson power difference?

Just got back from checking internal parts.
intake manifold, same
reed box assy, same
pistons, same
connecting rods, same
heads, same
crankshaft, same
throtle plate, same
carbs, same

So far the only difference in the two engines is an intermidiate orifice (jet).

 

[nymack66]

Re: 89' 120 and a 140 hp johnson power difference?

Bob, How many screws on the butterfly? Also how many reed petals?, on the 87 small bore looper the 120 and 140 is not the same. Yours is big bore looper..If you are absolutely sure its just the jets then its easy ...I know the part numbers are the same, however its listed under different HP respectively. I do not treat it as the same part so does my Dealer ...

 

[Bob Gilvary]

Re: 89' 120 and a 140 hp johnson power difference?

When I order a part number, I'm not asked what hp the engine is. Never have been asked.

If a part number goes along with several other engines, it's always been interchangeable between hp'rs.

I always look up parts according to hp though. It'd be stupid to do otherwise.

Last thing I checked was exhaust tuner, and lower exhaust housing, both have the same part numbers also.

Now if it was that easy to add 20 hp to this particular engine, I wonder what the cost difference was in 89' between the two, over changing out a jet on 4 carbs.

I know, it still may not be as simple as it looks, I'm still checking.

 

[boobie]

Re: 89' 120 and a 140 hp johnson power difference?

The only difference is the carbs between 120 & 140. 120 used carb # 432902 and 140 used # 432903.

 

[dazk14]

Re: 89' 120 and a 140 hp johnson power difference?

Bob,

It's a fair question, but Tasha is giving you good advice.

The extra power is made by at least the difference in intake manifolds and reed assemblies and it's the hidden "Gotcha's" that will keep you up nights (exhaust tuning,etc.)

Unless you have access to cheap used 140HP parts and someone that has done many of this type of conversions it's rarely worth the headache - although I have converted some motors over the years.

It's also not uncommon for the higher HP (same block) to idle worse and have less low end torque.

If you haven't already, the "right" stainless prop will often give you equal or better overall performance.

Hope this helps!

If you are still talking about the powerhead differences of the 1989 120 and 140 as I told you in the above, the manifold and the reeds ARE different.
You made me double-check at shop.evinude, hence the crabby attitude

BTW - 135 psi is GREAT!

 

[dazk14]

Re: 89' 120 and a 140 hp johnson power difference?

The only difference is the carbs between 120 & 140. 120 used carb # 432902 and 140 used # 432903.

On the early loopers, OMC couldn't make up its mind on port starboard carbs on 120's which were different from 140's and even changing during production years. It was crazy, but yours are the same(the stars aligned) jetting being the only difference.

 

[Bob Gilvary]

Re: 89' 120 and a 140 hp johnson power difference?

The only difference is the carbs between 120 & 140. 120 used carb # 432902 and 140 used # 432903.

But, if you would've looked further into the breakdown of each carb, the only difference in the two carbs is 1 intermidiate jet.

Check out part #21 on both the 120 and 140, you'll see they have the same part number. I know at the very beginning it shows 2 different carb part #'rs

Part #19 Is the only difference.

Shop.Evinrude is the only place I could find different numbers. All others sites that sell OEM parts for this engine show identical numbers. Strange but true.

OK, I'm done looking.

 

[dazk14]

Re: 89' 120 and a 140 hp johnson power difference?

Shop.Evinrude is the only place I could find different numbers. All others sites that sell OEM parts for this engine show identical numbers. Strange but true.

Personally, I'm glad you pushed - very worthy discussion. Sounds like you're really getting to know that motor and that always helps the Freebie forums!

 

[Bob Gilvary]

Re: 89' 120 and a 140 hp johnson power difference?

Personally, I'm glad you pushed - very worthy discussion. Sounds like you're really getting to know that motor and that always helps the Freebie forums!

Thank you!
I've only been doing this for 15 years and always learning. Iboats does get a lot of my business in parts.

 

[Asterope8]

I know that the bore size is a 0.30 on my 140hp. I'm pretty sure that would make a huge difference. I have a 90hp that I swapped the carbs, valves, exhaust, bubble back, prop and it only got me to 110hp. It made the boat plain out quicker if anything.

 

[steelespike]

I know your just trying to help but this is a 5 year old thread dragging a thread out of the past is frowned upon.
I have posted to long defunct threads that have been resurrected. I just did lol.

 

[emdsapmgr]

How did this really old thread get resurrected?

 

[racerone]

Folks find these topics using say " google "---then post on them.---Nothing wrong with that I say !!----Forum should block it automatically and direct folks to make a new topic and discussion if it is a big ---NO, NO..