lohnson 140 bubble back on a Johnson 115

[1983 ercoa 21']

Has anyone here taken the bubble back exhaust plate from a late 70s Johnson 140 and installed it on a late 70s 115 Johnson? If so what was involved in re jetting the carbs and was you happy with the end performance?

 

[emdsapmgr]

Re: lohnson 140 bubble back on a Johnson 115

Once you acquire the two bubble back exhaust manifolds, you'd need to get the exhaust filler block kit and have it installed in the exhaust chest. Used to be sold by OMC under part number: 392000. (It's obsolete now, but one US dealer still has a new kit in stock.) You are getting into a lot of machining work in order to complete this. (complete teardown required) You will want to make sure that your block has the rubber intake filler blocks, as well as the larger carbs from a 140. Also, the 140 had unique high compression heads. Once you get it setup, run the 140 carbs as jetted from the factory. You can decide if they need slight rejetting when you run it. I'd check to see if the modification was done to the rib at the bottom of the exhaust chest. Was on all the 140 blocks only. Picture attached of a 135 bubble back block with the 140 rib cutout.
Both blocks are 99.6 cubic inchers.

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

Oh I dunno. The only real machine work required is adding the rib cut out. That can be done with a grinder & cleaned up with a Dremel tool?

The big question is whether the 115 has the additional 'bosses' in the block to accept the exhaust filler bolts. If not then yes you do get into welding & machine work. And in that case it's probly not worth it. Filler block individual part #s are 323461 & 323462 btw.

You can do the exhaust mod(s) and not monkey with the intake with no ill effect. But then you're only getting a portion of the available performance benefit(s). Best to add the reed stuffers & 1 5/16" carbs too. Then you'd have a bona fide 140.

I'm currently building a '93 88 special block to 140 specs, and then some. But I'm always on the lookout for post '78 Johnson or Evinrude 140s. The hi-comp heads are gettin hard to come by, least down here.

 

[emdsapmgr]

Re: lohnson 140 bubble back on a Johnson 115

The rib cutout is only part of the deal. Once you get the exhaust filler blocks installed, you have to put the block on a mill and mill the exhaust deck flat so that the exhaust manifolds lie perfectly flat on the filler block faces. The two surfaces (block vs manifolds) must exactly be parallel to provide the proper clamp load on the manifold gaskets. If you re-use filler blocks, (which have already been cut once) you need to watch how much of the block deck comes off to make it all flat. Part of the kit are the bolts and special lock retainers.

 

[boobie]

Re: lohnson 140 bubble back on a Johnson 115

If I was the OP I'd just keep on running what he has and for a 15 HP gain it isn't worth it. JMHO

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

If I was the OP I'd just keep on running what he has and for a 15 HP gain it isn't worth it. JMHO

Not to nitpick but going from a 115 to a 140 would be a 25 hp gain? Regardless I recommend the OP save his money & trade up to a bigger motor.

 

[1983 ercoa 21']

Re: lohnson 140 bubble back on a Johnson 115

Alot of good information. Several years ago I had a 79 100 hp evinrude that I installed the bubble back and carbs from a 115 and it had a noticeable difference in power all I did was remove the bubble back from a blown 140 and with new gaskets.i also changed reeds with some from a local dealer don't remember the specifics on the reeds . This motor ran really well for many years.

 

[emdsapmgr]

Re: lohnson 140 bubble back on a Johnson 115

Another expert here on this forum (I believe it was Iwombat) had a thread about the type of bubble back install that you mention. Forget exactly his comments, only that he knew that the bubble back exhaust manifolds could be used without the filler blocks. I've always subscribed to the type of factory install-with the blocks, so can't attest to any performance gains. Check out this obsolete thread for more information http://forums.iboats.com/johnson-evinrude-outboards/115-omc-filler-blocks-249963.html

 

[boobie]

Re: lohnson 140 bubble back on a Johnson 115

You were right V153, I had a brain fart and couldn't add.

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

Another expert here on this forum (I believe it was Iwombat) had a thread about the type of bubble back install that you mention. Forget exactly his comments, only that he knew that the bubble back exhaust manifolds could be used without the filler blocks. I've always subscribed to the type of factory install-with the blocks, so can't attest to any performance gains. Check out this obsolete thread for more information http://forums.iboats.com/johnson-evinrude-outboards/115-omc-filler-blocks-249963.html

Very interesting. Is JHadley still with us?

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

You were right V153, I had a brain fart and couldn't add.

Eh well it happens to the best of us B. Walked out of home repot after buyin some stuff this am & almost tried climbing into somebody elses truck, parked the next row over. Was wonderin why the key wouldn't work when I noticed the tonneau cover over the bed. Then it dawned on me I don't have a tonneau ... Duh!

 

[1983 ercoa 21']

Re: lohnson 140 bubble back on a Johnson 115

I picked up a 1982 Johnson 140 over the weekend the model number j140tllcim the compression is 120/120/120/112 I picked this up for parts and was thinking about running the bubble back on my 115 Johnson. But I might take a look at the one cylinder to see how bad it's scorned might just fix it .

 

[bob johnson]

Re: lohnson 140 bubble back on a Johnson 115

Not to nitpick but going from a 115 to a 140 would be a 25 hp gain? Regardless I recommend the OP save his money & trade up to a bigger motor.

why do you think just changing the exhaust configureation, will net the full 25 hp??? I bet the carbs , the heads the pistons, and the porting....all have a hand in the final HP.........among other things

I wonder if that mod will even net 10hp, gain, by itself


bob

 

[1983 ercoa 21']

Re: lohnson 140 bubble back on a Johnson 115

I don't recall in any of my posts about adding the bubble back that it would add the full 25 hp. But it will add something when tuned right.
also in my last post I indicated that I might just fix the 140 .
if you read all my post on this it states I added a bubble back to a 100 hp years ago and it really brought that motor to life it was a noticeable difference. I'm not saying I know everything about a v4 so please don't misunderstand me I started this thread to gain information which is greatly appreciated.

 

[bob johnson]

Re: lohnson 140 bubble back on a Johnson 115

I don't recall in any of my posts about adding the bubble back that it would add the full 25 hp. But it will add something when tuned right.
also in my last post I indicated that I might just fix the 140 .
if you read all my post on this it states I added a bubble back to a 100 hp years ago and it really brought that motor to life it was a noticeable difference. I'm not saying I know everything about a v4 so please don't misunderstand me I started this thread to gain information which is greatly appreciated.

settle down, now.....my reply was to the quotes IN MY POST.....not to your post! if you go and look you will see that. I realize exhaust is big!! and how it is ported and controlled is important in tuning for HP. good luck.... I think you are better off on the path you are now on

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

settle down, now.....my reply was to the quotes IN MY POST.....not to your post! if you go and look you will see that. I realize exhaust is big!! and how it is ported and controlled is important in tuning for HP. good luck.... I think you are better off on the path you are now on

Yes. And my quote in your post was busting Boobies bad addition, in jest. It had nothing to to with the origional post.

In regards to intake/carbs please refer to paragraph 3 in post #3.

 

[bob johnson]

Re: lohnson 140 bubble back on a Johnson 115

Those old wives tales about what you can turn a similar model into a more hp model, are just that usually?.

Maybe?.way back in the 60s and 70s they did just increase HP by adding a different carb?but I can tell you for a fact there is a TON of misinformation reguarding a series of motors that I personally own? that?s the 60 degree loopers of the 90s. now that?s not the motor in question but it is my way of showing how things get spoken about wrongly and all of the sudden people start to believe it.

You can go almost anywhere that rebuilds outboards and they will tell you??rebuilt power head, fits 90 105 and 115 hp?s 60 degree loopers 95 to 99?..its lies!!!

They didn?t even make a BLOCK that would fit all those hp?s?. I know for a fact the 90hp and the 115 hp versions have TOTALLY different PORTING IN THE BLOCK!( yes its actually in the sleeves) PLUS the heads are about .09? difference in depth!!! And the carbs are way different in bore size.. but ?THEY SAY? they are the same block. And they will tell you that the power head in front of them can be used for the 90 hp or the 115 hp!!!!!!!!!!!!! Ha ha ha?.hogwash!!
Well I translate this in to much of the misinformation about how to make X motor into Y motor with ?JUST? a carb change, or a head change!! I would guess from the late 70?s there were probably carb head and exhaust changes from one HP model to the next, even when they LOOKED the same

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

Those old wives tales about what you can turn a similar model into a more hp model, are just that usually?.

Maybe?.way back in the 60s and 70s they did just increase HP by adding a different carb?but I can tell you for a fact there is a TON of misinformation reguarding a series of motors that I personally own? that?s the 60 degree loopers of the 90s. now that?s not the motor in question but it is my way of showing how things get spoken about wrongly and all of the sudden people start to believe it.

You can go almost anywhere that rebuilds outboards and they will tell you??rebuilt power head, fits 90 105 and 115 hp?s 60 degree loopers 95 to 99?..its lies!!!

They didn?t even make a BLOCK that would fit all those hp?s?. I know for a fact the 90hp and the 115 hp versions have TOTALLY different PORTING IN THE BLOCK!( yes its actually in the sleeves) PLUS the heads are about .09? difference in depth!!! And the carbs are way different in bore size.. but ?THEY SAY? they are the same block. And they will tell you that the power head in front of them can be used for the 90 hp or the 115 hp!!!!!!!!!!!!! Ha ha ha?.hogwash!!
Well I translate this in to much of the misinformation about how to make X motor into Y motor with ?JUST? a carb change, or a head change!! I would guess from the late 70?s there were probably carb head and exhaust changes from one HP model to the next, even when they LOOKED the same

My experience is with '78 & newer crossflows. I believe the port size & timing is the same from '78 up regardless of hp rating. All mine are ...?

 

[1983 ercoa 21']

Re: lohnson 140 bubble back on a Johnson 115

So what are the tricks to getting extra hp from a cross flow v4 motors?

 

[V153]

Re: lohnson 140 bubble back on a Johnson 115

Eh well, y'know. A lil of this & a lil of that.

Note: Piston(s) have yet to be scalloped.