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Building the Johnson 140

wired

wired

Well-known member
I started working on building a Johnson 140 a few days ago. My original intention was to build my 90 into a 140 but that thing runs extraordinarily well and it seems a bit silly to carve it up . I did a bit of looking around and picked up a 115 block with the intention of opening it up for the 140 exhaust components. Then I find a complete 140 motor on craigslist for $175 and picked it up too. You cant have too many parts I suppose. So I tore into the 140 and found a problem with the block. One of the cylinders is deformed and the aluminum on the inside of the water jacket next to that area has broken off. That may or may not be a problem and it might bore out just fine with no other consequences but in any case I still have the the 115 block to work with. So I machined out the lower ribbed section and spent a little time squaring up the ports. I want to keep the revs under 6200 ish so I didnt raise the ports. I did fly cut the exhaust blocks to match the block . I'll have both blocks machined to match my pro marine pistons and I can always build another if I blow the first one up. I did have a few threads that got destroyed in the disassembly process so I welded up the block in 5 spots and welded and smoothed out the ports in the bottom going to the exhaust. I'll be using some 175 XP 1 3/8" carbs and fiber reeds and a smoothed and textured intake. Anyway here it is so far...

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Well I got her all blasted, washed and off to the machine shop today. I had another actual 140 block I was going to send along for a bore job too but that block has some damage to the #1 cylinder water jacket and I havent had an opportunity to weld it up yet. Should just be a simple patch job but i didnt want to send it as is and then have to weld up the aluminum later and distort the bore. Anyway hope it doesnt take too long at the machinist.

I had pulled the 140 heads off the core 140 I bought and put them on my Johnson 90. Running so good I don't want to take them off now. I was looking for another set of 140 higher compression heads but those arent growing on trees these days. Back to my original plan of opening up some 85 HP heads to give me 135-140 cranking PSI. 85 Heads are dirt cheap and widening the sides of the chamber is a 10 minute job on the mill. I like the fact they are true quench heads as well instead of the open chamber design that look like a late Ford Cleveland. Should work well.
 
If you ask me, the absolute best 4V crossflow heads are the 1978 85 HP heads. Getting into the 70's and 80's they were dropping compression with the bathtub configuration which if anything made detonation more problematic. The quench configuration of the 85 HP heads is ideal. The '78 heads have the late coil mount brackets and dual overheat sensors. The pics here are of 85 horse 1978 heads that I picked up off ebay for $40 shipped. Perfect threads. These are 85 horse evinrude heads and I'll have to open up the chambers a bit on either side for piston clearance with a ball end mill for the 3.53" pistons but its just a 10 minute deal on the mill. I'll put up some pics of the finished heads once complete.


As a side note I pulled the intake off my 90 HP today to pull the reed cages out so I could install some CC fiber reeds and rubber stuffers and I found rubber stuffers in there already. Theyve been in there since the engine was purchased new in 1981 . The intake has never been off and I have always thought that in that era they only came in 140's.



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Heres the 85 heads opened up for the 3.53" pistons . They'll need some CC adjustments once the engine starts going back together. 2 cycles are damned impossible to figure out cranking compression from static compression ratio. I'm shooting for 135-140 with premium straight gas.






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Just got off the phone with the machinist. Its all done and they are sending it back today. Those guys kill me. They'll send me an invoice for payment withthe block. $25 a hole bored and diamond honed and yes, they do them quite often.
 
Block came in today. Looks great. Round trip and the work came out to around $170. Seven day door to door. Not too bad. Only thing I'm waiting on at this point is the O rings for the end bearing retainers and the end lip seals. I didnt realize they didnt come with the gasket set until a few days ago. Gives me a few days to paint the block red and get the pistons set in the bores while I get the crank ready.
 
Wired I don't know how to rebuild OB motors, so I can't offer anything other than thanks for sharing!!!!:thumb:
 
Got a bunch together today. 2 cycle outboards are the worlds simplest engines. No cams, no oiling systems etc. Theyr'e almost fun to work on. I'm going to take tomorrow off since my parents are coming down for the day and dad wants to take the boat out. Ive got to show off the Boyesens. Anyway I'll get back to it Monday. I need to lap the reed cages on the kitchen granite counter tops and you know what that means... The wife has to be working. I'm building these with Chris Carson reeds and I'll take a few of the process.

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Here are the Chris Carson reeds installed in the reed cages. The cages have been lapped with 1200 grit sandpaper and the screws loctited in place. The intake stuffers are installed next to the reed cages and everything has been torqued down.

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My dad came over the other day and we went for a ride. I showed him the new engine and he asked why I was painting it red. Red is faster. Hello . Everyone knows that.
 
The good thing about having a whole core engine is I have all the wiring and electrical, plumbing etc. I was able to get it all together on the bench and manhandled it onto the motor yesterday. Gave it fire today. Sounds like a chainsaw. I'll have to pull the heads apart and use sealant on the head cover plate gaskets . The are leaking a bit. Rings havent quite seated yet and there is a bit of pop back into the manifold at idle but it sounds good. I'll have to get the leakers sealed up and fire it up again on the weekend when I have time to run it for more than ten minutes at 2000+ RPM . Too late today to be pissing off the neighbors.
 
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