OMC 115 HP question.

[rev.ronnie]

I building a 115hp Evinrude powerhead for a customer right now. It is going on a classic restored boat (Glaspar G-3), and all out top speed isn't a huge factor. The boat actually ripped pretty good with an old, tired 90 on it. I'm just boring it .020" over and squaring up the heads and block. It will be a stock type build. I will be using all Sierra parts.
Is there anything that comes to mind with these since it's apart and on the bench? Any updates or upgrades that I need to be aware of?

What are the best reeds to run on this powerhead? I know there are several available but I'm leaning towards CCMS reeds. They seem to bee well respected on here and they are an advertiser too. (that goes a long way for me)

What are people's experience?

Thanks, Ron

[EMDSAPMGR]

You are probably working on an older crossflow engine. Would help to know the year. These engines went through many upgrade/changes over the years.

[rev.ronnie]

It's a 1978. It is a cross flow it seems. I don't really know the difference. Intake ports in one side, exhaust on the other. I bored it .030" over. One cylinder had a scrape up the side and I had too move the bore over .008". I think Wiseco makes a piston too. I'm thinking I may run them instead of the cast Sierra pistons.

[Riverman]

Check the locating pin for the centre bearing, sometimes they get pushed in too far and allow the race to move around.

[ChrisCarsonMarine]

Ronnie,I would rather see you use Vertex or pro pistons,the rings that come with the Sierra pistons are fragile.you don't need the wisecos for strength,so I wouldn't risk the sticko's possibility...although they do pretty well in crossflows.we make a great sport reed for your motor,you'll like it and the price,80$.Ive built literally hundreds of v4's,if you need advice or parts give me a call,Chris

[rev.ronnie]

Thanks for the info guys,

Chris, I'll have the guy call you and order them this week, thanks!

[rhickox]

Building a 77 model now. I'm going with the pro marine pro-v pistons .030 over. From what I have been told, if u put the bubble back inner and outer exhaust cover on it along with the 135 h.p. carbs and clean the exhaust chest/ports up a little it will make a big difference...The bore and stroke on the 115 and the 135 are the same according to the OEM manual I got from a local dealer...If ur gonna run the motor at idle speeds a lot, the service manual says use the champion plug specked for the 115 gapped at .040...

[EMDSAPMGR]

The 78's were the last year for the small crank bearings. As is, it should still give many years of good service. That engine came with the 140 high performance rubber intake filler blocks-a nice addition for added hp. Composite reeds would make a nice addition for your customer. They really help idling and midrange.

[rev.ronnie]

Good info, I'll have the guy start looking for the bubble back back cover and some carbs. This boat actually gets used for smoking and tubing and well as shows, so he'll like it with some extra power.

[flabum1017]

Your 140 should already jave the bubbleback cover on it.....I have a new set of exhaust stuffers for sale if you need them

[rev.ronnie]

It's a 115 I'm building. I'm guessing the 140 stuffers are what I'm looking for?

[racer]

I have the exhaust parts and should also have a set of 140 heads/carbs

[EMDSAPMGR]

The parts racer has would really make a nice addition to the powerhead.

[tony1204au]

Am I missing something here???
If you put the bubble back exhaust plates on a non bubble back block, wont you need to machine lots of metal off the bottom, and also use the exhaust filler blocks???
I did this once, and it wasnt as easy as I first thought.... but still doable....

[rev.ronnie]

Honestly, I'm not up to speed on OMC stuff beyond doing the machine work, which is usually boring, welding, surfacing and sleeving. The guy was actually pretty happy with the way his worn out 90 ran. It went high 40s and he was cool with it. I should be a vast improvement with a fresh 115 and some reeds. If he wants to go with the 140 parts, that would be even better. I'll talk with him tonight.

[racer]

Yes you have to cut the block and machine the gasket surface after the fillers are installed. Its easy with the right tools.

[rev.ronnie]

Probably would be a walk in the park on the Bridgeport I would think.

[EMDSAPMGR]

246266 Bolt the exhaust fillers blocks in place and deck the
back of the block. Depending on which block you have, you may need mill out the area at the
bottom center of the block.

[rev.ronnie]

Thanks for the pic! Nice to see what it looks like. No problem machining that, should be easy.

[rev.ronnie]

Well, the 115 is buttoned up. It all went together like a dream. I ordered a set of reeds from Chris Carson today and got my money's worth in reed valve education alone. He took the time to explain some of the nuances of different reeds, cages and designs for this OMC, my 260 and then some.

Thanks for the info Chris, great talking to you. I will be buying all my reeds from you, from here out!

The boat/motor should be at the Mpls. boat show, as he was invited to show it. It is a fully restored, Glaspar G3.