evinrude 85hp 1979 V4

[oldglastron]

hey guys got a few questions,
I finally got my manual the other day (OEM) it rocks! now I know why everyone says to spend the money it is worth it. My question is what do I use in the lower unit for oil. can I use gear oil like GL-4 or does it have to be marine lube? I know I don't need to use the type C like my older engine but I would like to be sure. The manual just says Evinrude brand.

My second question is a little more interesting. When I was looking at the specs in my book I noticed Bore and stroke are the same from 85-140hp engines,so what makes the difference in HP I noticed the carbs exhaust housing and reed cages are differnt part numbers but that is about it I would love a little extra power from my 85hp as I live at 5000ft here in CO. Also has anyone used the Bosyen reeds? and are they worth the money?
thanks,

James

 

[F_R]

Re: evinrude 85hp 1979 V4

I'll let you decide for yourself what to use for gear oil. Fortunatly, the gears and stuff are built to withstand 140hp, so at 85 they aren't stressed as much.

Anyhoo, the horsepower question comes up almost every day. If you want to go through the parts books and pick out EVERYTHING that is different, you can make a 140 out of your 85. But that word "everything" might/could include cylinder block, pistons, cylinder heads, exhaust covers, carburetors, reeds, midsection, etc, etc. Generally, the things that increase horsepower are compression ratio, carburetion, porting, and exhaust tuning. It is all related. For instance, changing the carburetors won't help if you don't address the exhaust tuning issue. In fact it could actually get worse. How deep are your pockets? Have you priced a set of carburetors yet?

Being a Flat-lander at sea level here in FL, I am totally unfamiliar with what it takes to make these things run at 5000+ feet. You are better off checking with local Evinrude dealers to answer that question. You have to set them up to run leaner..is that right? Or is it the other way around?

 

[jay_merrill]

Re: evinrude 85hp 1979 V4

Less atmosphere = less fuel. I didn't look this motor up, but chances are that it has fixed high speed jets, which will deliver too much fuel in the thin air of a 5,000 MSL location. I don't know if OMC offered "high altitude jets" for this motor, though. As suggested, probably best to talk to the local mechs - they'll know what to do.

On the slow speed side of things, it should be eay enough to lean the mixture a bit.

 

[emdsapmgr]

Re: evinrude 85hp 1979 V4

From a pure bolt-on perspective: A set of 135 1 5/16" carbs will help, but you'll need to spend time rejetting them to get them to run. I like the composite reeds, tho they will improve idle and midrange acceleration more than they will top end. When you have the intake off to install them, I'd add 4 of the NLA 322684 intake filler blocks from the 140. They will typically buy you more than a few hp. A set of early 140 heads would be good from 1977-79 vintage. Before you get into engine mods, be sure your max out our setup by raising the engine on the transom. When you are all done, you'll need a high rake stainless prop for it.

 

[oldglastron]

Re: evinrude 85hp 1979 V4

Thankyou for your help guys.

It seems like alot of the V4 stuff could be swapped from motor to motor. I got the parts manual as well as the service manual. Alot of the parts are the same. The carbs are different, the exhaust, reeds. I had not looked at the heads. Higher compression for sure but its the heads that must raise the compression, as pistons rods and blocks are all the same.

I have rebuilt the carbs and done a full tune up it runs better for sure, but the altitude kills it. I had a 3 cyl 70hp evinrude that ran 40mph in FL. Here in CO I have a 4cyl on a smaller boat (both were tri-hulls) and I get about 38mph. and yes there is alot of other things that can affect speed prop etc. but you know what I mean. I wish I had more cash for a bigger boat and engine, but my 85hp will do for now... even if I have to throw everyone in the bow to pull a skier out of the hole. I have one last question do you think I would benifit from a four blade prop? I use the boat for towing skiers and tubes I think its a 13pitch 3 blade now I can verify.

 

[oldglastron]

Re: evinrude 85hp 1979 V4

From a pure bolt-on perspective: A set of 135 1 5/16" carbs will help, but you'll need to spend time rejetting them to get them to run. I like the composite reeds, tho they will improve idle and midrange acceleration more than they will top end. When you have the intake off to install them, I'd add 4 of the NLA 322684 intake filler blocks from the 140. They will typically buy you more than a few hp. A set of early 140 heads would be good from 1977-79 vintage. Before you get into engine mods, be sure your max out our setup by raising the engine on the transom. When you are all done, you'll need a high rake stainless prop for it.

I ordered the reeds this morning and I am going to hunt down the blocks. I will do little improvments at a time and see what I gain. Thankyou.

 

[jay_merrill]

Re: evinrude 85hp 1979 V4

I would get the motor set up to run properly at your altitude before I would worry about the prop. Generally speaking, 4 blade props do help hole shot, but putting one on the motor isn't going to help, if you can't develop the torque to turn it.

 

[oldglastron]

Re: evinrude 85hp 1979 V4

Thankyou Jay,
I will contact the local marine guy I know Monday and find out about the jets for sure, and yes we lean things out at this altitude. The engine runs fine well after I rebuilt the carbs anyway it purrs at idle and takes off ok but could use more power.

 

[jay_merrill]

Re: evinrude 85hp 1979 V4

I'm not surprised. I once rode a Honda 750 motorcycle across the US, and passed through Denver. I noticed the degredation in power there, but really noticed it when I drove over the Rockies, eventually making my way to Utah and then the West Coast. At 12,000 feet, the bike had the power of a 250, not a 750!