'79 140 Evinrude crossflow rebuild "project"

[Fuzzbutt]

Well in the interest of finding a better HP candidate I found a 140 for sale at a decent price but it was "unknown". This is my first outboard but not my first motor and I learn quick. I didn't want to tear into my slightly hurt 100HP Johnson (same year) as I think my 100 only needs a piston on #3. Anyway back to the 140.

I got her apart a month ago and have had the block at what sounds like either a very busy or a very poorly run machine shop somewhere in the Detroit metro area. I finally got some news from them about the condition of my block. Seems it was already bored out to 3.540 and it needs to go out further to repair the wear and damage from the rings that were broken on 2 of the pistons. So it looks like I am going to be headed to .060 over. And due to that it also looks like I am headed for Wiseco pistons. Specifically the 3173P6 variant. I'm hoping the "shop" heard what I will be running and sets it up for success and not just bores it to 3.560. I'm not sure how much extra diameter it is going to need to live and make good power at 5700-6200 rpm on my CVX16.

I know it's not the fastest thing on the lake but I like it and my lowly 100HP V4 spun 5800 at 56MPH so I figure the extra 40 odd ponies will see a few more RPM.

Anyway the block isn't back yet. I haven't ordered the pistons yet. What tips or exact measurements should I look for? I'll buy a micrometer and do what ever it takes to make sure this is right cause there is going to be nearly $2000 in this thing by the time I am done with it.

On the bright side she'll be running a set of CCMS's reeds. And so will my 100 when I tackle that project.

I'm sure I'll be running into other little questions so this might be an on-going thread. sorry about that in advance.

[FMP]

Do all the cyl. Wiseco are good to what it says on the box. Maybe add a 0.001 . Check all end gaps , make sure bores are straight. Chamfer all ports by hand. Use good oil, proper break in. Nothing to it stock rebuild .

[Fuzzbutt]

Yes all the cylinders are getting new running gear. I'll break out my feeler gauges and verify everything.

[flabum1017]

Wiseco is calling for a 3.564 bore.......... http://www.wiseco.com/ProductDetail.aspx?ItemID=3173P6

[FMP]

That's cool, .064 over. I'm sure the pistons are just small enough to give the proper clearance. Must be enough sleeve to cut , so they went extra ???
Never cut a bore without checking the piston first , cart before the horse!

[EMDSAPMGR]

The factory pistons go up to .030 over. During a rebuild they do not specify any need to rejet the carbs. Since you are going significantly above .030 over, you should plan on jetting the carbs up slightly to keep the combustion chambers cool.

[Fuzzbutt]

Great thanks for that tip EMDSAPMGR. I'll take a look at my current jetting situation and see what I can do about fattening up the mains but I don't know which way to go on the idle circuit.

Yes I know I'm putting the cart before the horse. I suppose I should have had the pistons in hand when I told them it was good to punch it out to .060 over but I specifically said I'd be forced to use the forged pistons and I am pretty sure it needs .064 over.

When I get it back I was going to make sure the ports are smooth and might also knock off rough areas in the intake and exhaust areas to help with flow a bit. Figure a bit of smoothing might be good.

Since it was already .040 over I bet the wrecked pistons I have are forged also. I wonder why the rings self destructed on them? Might be too lean so fattening up might help that.

[FMP]

.060 over and you're not going have the clearance, bore to what is on the box and double check the piston size. The piston is made for the correct clearance , so its prob. .058 over or a bit smaller.