V4 powerheads interchangeable?

[fsds123]

I have a 1979 Evinrude 115 V4 that has at least one bad piston, and am debating on which route to take (complete or partial rebuild)

Another option would be to buy a good used powerhead. Which years fit? Do higher hp ones fit, and if so, anything else need to be changed?

 

[Dhadley]

Re: V4 powerheads interchangeable?

Any V4 crossflow from 79 & newer will work. The ones from 78 and some from 77 will too but there are some internal differences. To keep things as simple as possible try to stick with ones from 79 & newer. There's even a simple way to tell what year the block is if the core plug with the numbers is missing -- if the front lower pan mounts are cast as part of the front half of the block, it's a 79 & newer. If they bolt on, it's older.

 

[fsds123]

Re: V4 powerheads interchangeable?

I found a guy selling a late 70's v4 115hp evinrude for parts...he is not sure what year. Any way to tell from these pics if it is a 1979 by chance? If not, should the block and pistons at least fit?

 

[HighTrim]

Re: V4 powerheads interchangeable?

Here is a rebuild kit from ebay. One option.

"http://cgi.ebay.com/ebaymotors/POWERHEAD-REBUILD-KIT-JOHNSON-EVINRUDE-V4-CROSSFLOW_W0QQcmdZViewItemQQcategoryZ50439QQihZ016QQitemZ260172927050QQrdZ1QQsspagenameZWDVW"

 

[ezeke]

Re: V4 powerheads interchangeable?

The parts in your photographs are from an engine that is no newer than 1978. The welch plug is visible so ask the seller what the numbers on it are.

 

[fsds123]

Re: V4 powerheads interchangeable?

The part number is 115793s, which according to google is a 1977. So now the question is what parts are interchangeable.

 

[Dhadley]

Re: V4 powerheads interchangeable?

Remember what we talked about earlier? Look for the cast on mounts, not the bolt on ones like this one. The crank will not work in your block and that block will not bolt up to your midsection. Even if it did it would basically make your 1979 motor older.

 

[fsds123]

Re: V4 powerheads interchangeable?

I guess I'm not sure which mounts you are referring to. In which picture can you see them, and should I be able to see them on my motor with it still being bolted in place? All i've done so far is take one of the heads off.

 

[ezeke]

Re: V4 powerheads interchangeable?

If the number that you gave is off the welch plug, than the engine block is 1977, and not the right choice for you.

 

[Dhadley]

Re: V4 powerheads interchangeable?

Look at the front half of the block itself (not the intake manifold). At the bottom there is a mount on each side with a rubber gromment in it. On your 79 block that mount will be cast as part of the front half. On older models those mounts will be bolted to the front half.

 

[fsds123]

Re: V4 powerheads interchangeable?

Ah, I see thanks. One more question if you don't mind. I also asked this in the other thread I have open:
After a little better inspection, it looks like only the one piston is bad. (I still need to pull the powerhead and take a better look). From what I've read, my 1979 pistons are the high ring piston types with higher compression that were discontinued after 1979 or so. So would replacing the one piston be a bad idea, since the replacement would not be a high ring type?

 

[Dhadley]

Re: V4 powerheads interchangeable?

Don't worry about what the pistons or cylinders look like. Once you measure the bore you'll know how many are going to be bored. Don't forget -- you measure the bore before it's honed to see where you're at and then after it's honed.

You have .004" wear tolerance. If it's at .002 or .0025 now and you hone .001, the you're starting a "fresh" rebuild at .003 to .0035 over. That only gives you another .0005 to .001" additional wear. Starting at .003" wear means you have 1/4 the wear left in that cylinder. (3/4 of the goodie is gone)