76 Johnson 25hp/ 77 Evinrude 25hp powerhead interchange

[Lectrick]

Hi all. I've got a 76 Johnson 25hp electric start outboard with a powerhead that's going south. I found a complete powerhead for a 77 Evinrude 25hp on Ebay, and I'm wondering if it's a bolt on replacement? Is there special casting I need to look for to accommodate the electric start (starter motor)?

Any help would be greatly appreciated. I've tried looking all over and I can't seem to find a definitive answer on this.

 

[flyingscott]

I will say no because the 77 is a 31 CID block where the 76 is a 22 CID you need to either rebuild yours or find a 76 or older block. You will need to do some research and find out which blocks interchange.

 

[oldboat1]

sounds like a pretty big change in a year. You could find a couple of parts blowups to compare bolt patterns, maybe check gaskets for the two engines for a clue. Haven't looked at the starter mounting similarities or differences, but could be a matter of getting a mounting bracket that fits(?)

 

[TN-25]

Don't look to a 1977+ as a possible donor for a 1976 motor. They are entirely different generations. Look at 1976 motors and back. I would guess that heads back to 1969 would work.

Electric start was optional through a kit, but for 1974 the electric start once again became a factory option (for those with a long memory the 1958 18 was offered with factory electric start). The 1976 25 was based on the 1957 22 c.i.d. 18 horse that was turned into a 25 for 1969 by virtue of a better intake & reed valve setup, exhaust bypass cover, carburetor, plus a heavier crank designed to spin 1000 rpm higher.

 

[oldboat1]

yeah. took a look and starter brackets seem to be different too (and different sides of the engine, I think).

 

[racerone]

Blocks are totally different.---Starters and brackets are different.--Starters are on the port side on both models.----As stated you need to look for a doner block from 69 up to 76 for the 25 models.

 

[kodibass]

TN-25 not trying to steel thread just was wondering so then would a 1972 25 hp swap with a 65 18 hp? I have a nice 64 or 65 18 but it has rod slop/knock I was given a nice running 1972 25 hp that has no lower or transom brackets but the power head is fine, if I'm reading your post correctly sounds like a match? Also I have a beautiful 1958 electric start 18 I got from a fellows old collapsed shed for hauling the rubble off for him One of my favorite kickers.

 

[racerone]

That is the beauty of these motors.----So easy to work on and so easy to find parts.---The 72 powerhead will fit on the 65 model.----These motors will be around long after some of the new stuff on the market today.

 

[Chinewalker]

That is the beauty of these motors.----So easy to work on and so easy to find parts.---The 72 powerhead will fit on the 65 model.----These motors will be around long after some of the new stuff on the market today.

Sort of. The '72 will use the large carburetor, and as such the knobs will be slightly off and may not align with the holes in the cowling. Some fudging may be required. It is possible to put the '65 intake and smaller carb on the '72, though...

 

[kodibass]

Great'" I don't mind making new holes etc. in the front or other fudging, to get things to function I'm looking to make it just a good runner. Then I will rebuild the 18 block later, I have 3 mid 60 lowers + pans & cowls and most other parts, but it will be fun to set a 25 in a 18 package vrrrrrrrrrrrrrooommmmm