84 115hp evinrude vs 79 115hp johnson are they the exact same block?

[comet424]

hi i bought a 79 115hp johnson for the crankshaft as the marina said the 79 and 84 are the same crankshafts just have different numbers

but i wanna know is the block exactly the same?? as i was going to have the 79 repaired have 1 cylinder bored instead of 2 like on the 84.. and i was going to put the 84 parts on the 79

if not then ill just have the the 84 rebored.. but just wanted to know what parts are exactly the same and if the blocks are the same

 

[emdsapmgr]

You can compare all of the parts on each motor by going to the official factory parts website and examine the exploded parts diagrams-comparing each. check this site out: epc.brp.com The only problem will be that many of the part numbers may supercede, yet are actually the same functional part. For instance, many of the pistons from the 79 vintage were high ring pistons. The factory discontinued them in favor of lower ring (more reliable) pistons. Both are considered interchangeable, yet will have different part numbers.

 

[comet424]

ok ill check it out i know boats net shows different numbers they look the same.. marina told me the crank shaft are interchangeable. the difference i noticed the 84 has a more counter weight i uploading a video as it also has like punchholes i not sure if thats just from the form when it was made ill upload

 

[comet424]

No Title

ok i still waiting for video to upload its not the best video as i was tring to get the light in on the crank

but here is 4 pics for now 1 you see the 79 crank has divitos is that just from when they made it??
and you also see the 84 crank its got some extra meat in the center where the 79 crank doesnt so does that matter? even though tis interchangeable?

also the pistons the shinny one is the 79 the dirty one is the 84 i guess they used the same top pistons no lower ones??

i looked on the site you sent i cant really tell a difference the drawings are the exact same numbers changed a bit it looks but majority the number is all the same 70 is on both as example.

and would the electrical be the same on the 79 and 84? or aare they significally different?

 

[comet424]

here is the link its not the best but hope it helps you see i have divots on the 79 and the 84 has some extra weight?

 

[racerone]

I second the opinion and knowledge of the mechanic at your marina.---Often a novice will question someone with years and years of experience.---Again , use the crankshaft as they are the same.----------Based on 40 + years of experience.---Different part #'s are to be disregarded here !!

 

[Bosunsmate]

Question everyone always

 

[racerone]

The superceding part #'s can easily be looked up !!-That would confirm that these 2 cranks in question are in fact the same !!!!

 

[V153]

Assuming the '79 has the large journal center bearing all parts should interchange. Blocks are the same otherwise.

Weight of cranks does vary. I have some that are 3 lbs heavier than the lightest.

I believe the electronics are bout the same on those 2 years. Regardless I'd upgrade to the single powerpack CD4 box. You can get a new one for under $100 bucks.

My guess would be those 'divots' are just from a sloppier casting. Shouldn't be any cause for concern.

 

[comet424]

ah ok thanks guys.... i was just questioning it.... about the extra weight as you see on the crank,,, i always ask for 2nd 3rd opinions as i dont wanna damage the crap right...
and ya the 2 cranks exactly the same just the lower bottom had that extra weight on the 84.... the reason i replacing crank is the machine shop didnt like this little rust divit on the where the bearings run said it cant be buffed out told me to find a new crank thats why i just asking extra questions

and as for the cd4 box is that the newest stuff for the engine? do you still need the 4 coil packs or is that ok to use? ill take a video tommorow or so showing what i got as i not sure i dont wanna make any mistakes right...

so then then 2 blocks are exactly the same? just different numbers as then i can use the 79 instead of the 84 then i gonna clean them up and hone the 84 as it has rust in and double check....

and ok thanks abotu the slopper casting wasnt sure the 79 suppsoedly had a bad piston but i not sure i think 2 were bad id video tape and show... i know the 84 the engine siezed and the 2 Over sized to 30 scracthed the cilinder walls so they have to be bored out...

 

[comet424]

oh and when i tried to look up the crank shaft numbers... i couldnt tell if the 79 and 84 used the same crank shaft... as when the 84 it was only in 84 85 outboards... from boats net website... so i had to ask a marina to find out.... but how else would i find out if they used the same crank shafts???

 

[comet424]

oh ill have to video tape but i was just looking in the 79 cylinders 1 is grooved up from being siezed.. and another cylinder has 2 long parrelle grooves the lenght of the cylinder what is that for? the 84 doesnt have that... and hwat causes 1 cylinder to to scratch up?

 

[racerone]

Both motors have the original part # for the crankshaft superceded to an identical part # at one time !!!!!!!!--The parallel grooves are damage !---Each carburetor bore feeds one cylinder.--If a carburetor is plugged that one cylinder runs lean on fuel AND lean on oil too !

 

[comet424]

ok kinda confused.... here is the video the first part is the 84 with the rust in it.... the 2nd one you can see the scratchs in the 79 but you also see the 2 groves perfectly straight and smooth cuts in the cylinder what is that???
and you lost me how do you know they the same numbers?? boats net shows the number for the 84 Crank as 0393751 and the 79 crankshaft number is 0389599 so those are 2 different numbers... what i mean is what website you looking at that use the same number??? if its not boats.net then what website
and i not sure what you mean the orginal part number of the crankshaft superceeds the identical part number at one time... Im only going by what boats.net part number is for each crank shaft.... thats why i asking where do i find out that these are the same.. and one top of that whereever you find that info i wanna make sure that the block and all the parts were the same too.... is there a website that says what parts are interchangeable but even have different part numbers

 

[racerone]

That groove is from a loose wrist pin clip or from a wrist pin !------Do you not believe that these motors had original part #'s superceded to the same part # ---If not then why not ?

 

[comet424]

ah ok
and i have no idea what your talking about... that they had a orginal part number to the same part number... i gave you what the website gave for the orginal part number for 84 and the orginal part number for 79..... if there is another number your talking about then where do i find this website?? so i can figure out if all the parts on the79 is exactly all the same parts on the 84... send me link so i can figure it out.... as the marina doesnt know if the blocks are the same or the wiring just they only knew the crankshaft wasnt the same just interchangeable... so what would they be using to find this information so i can try to figure it out..

 

[comet424]

so does the 79 orginal part number superceed the 84 part number so that they are exactly the same so i can put all the 84 components on the 79 block?

 

[comet424]

also what is the cd4 box??? and looking at the electrical systems. the coil packs different.. but the power pack assembly look the same but are different part numbers.. are they also exactly the same with just a different part number? so is it swapable like the crankshaft?

 

[emdsapmgr]

The 79 power pack 581805 supercedes to the 582125-same as on the later 115. The 79 power packs are unlimited packs-later packs are rev limited to 5800 rpm's-a detrimient to the hotrodders. The 79 coil 581998 eventually supecedes to 584561, which is what the 84 115 supercedes to. The coils do not look alike. The later coils have removable spark plug wires-the 79 coil wires are potted in the coil itself. Functionally they are the same and can be mixed on an engine.

 

[comet424]

ah ok and is this information easy to find when your not a mechanic what parts supercedes? so when you say 79 supercedes the 115 in 84 does that mean the 79 power pack is better then the 84 powerpack? i guess you just have to be the mechanic to know all these parts then what parts can be switchable... so does that mean on my 84 it can only hit 5800 rpms and the 79 can higher.... not like i wanna do that... I have also the VRO 2 pump can that be added to the 79 block

so far the only thing i seen the same is the timer base and stator is only part is the same.... thats why i just asking questions on what parts i can swap in an out as my 84 on the coils are the same on the 79 removable but the diagrams show 79 doesnt have removable coil pack wires... so i guess those are upgraded..

i guess maybe superceeds is other words an upgrade... and i guess only a marina or mechanics would know and i cant go by what boats net or this forum or the brp for the part number goes by just go by what the marina gets you the parts for right? as they probably have a database for the upgraded parts that work for that year