1981 35 horse Johnson worth rebuilding?

[58rude]

Re: 1981 35 horse Johnson worth rebuilding?

Thats a new one on me. Every piston manu. I have ever seen will tell you what side clearance they want and ring gap depending on application being used in.

PS
That is a cool looking little boat, if its rated for a 50, I would put that on it. I bet that little boat is alot of fun.

 

[jbjennings]

Re: 1981 35 horse Johnson worth rebuilding?

I love the boat, too. My opinion is that even if the motor is in perfect shape, a 35hp is not going to get a boat much past 35mph. A 50hp would be awesome!!! Faztbullet is a real outboard expert; I'd love to have one of his tuned motors if I were lucky enough to have a boat like yours to put it on. What kind of boat is that, BTW? I'd like to have one exactly like it! Handmade??
Later,
JBJ

 

[TN-25]

Re: 1981 35 horse Johnson worth rebuilding?

A bored-out 35 with some porting work doesn't seem like a bad idea to me, for what it's worth. Yes though, a looper 50 with a Nitro gearcase would give you what you are looking for on that hull, a fast hull with low drag. Either way is good IMHO.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Check your Pm!!!!! ,,,,and you got to watch Mike, as the kit he sells is from WSM( I sell also) and he dont make anything in kit.

Faztbullet, since you sell the same kit, what would you tell me if I called to ask you about piston clearance? Is WSM someone that I can contact with this question?

 

[Faztbullet]

Re: 1981 35 horse Johnson worth rebuilding?

Well a piston not round and is actually tapered, as the skirt is larger than the OD at top ring land.Take a Merc inline for instance as the spec are: skirt=2.872 & land= 2.863 with a finish bore of 2.875. This give .003 clearance AT skirt and .012 at ring lands(that why a piston rocks in its bore). The side clearance is only as good as the person and machine boring it(block). You want a finish bore of 3.030 for .030 pistons. When I bore a block I will bore say in your case to 3.028 and finish hone out to 3.030. This puts finish bore at around +/-.0005. You can call Anthony @ WSM at 1-866-417-4072

Anyhow, if this thing doesnt pick up 15 or 20 mph with a good powerhead,

Sorry as you will be lucky to pick up 2 mph, it takes about 5 hp to pick up 1 mph.. To pick up that much you need to find a 78-81 3 cylinder short shaft 75hp or a older Stinger 70-75hp.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Well a piston not round and is actually tapered, as the skirt is larger than the OD at top ring land.Take a Merc inline for instance as the spec are: skirt=2.872 & land= 2.863 with a finish bore of 2.875. This give .003 clearance AT skirt and .012 at ring lands(that why a piston rocks in its bore). The side clearance is only as good as the person and machine boring it(block). You want a finish bore of 3.030 for .030 pistons. When I bore a block I will bore say in your case to 3.028 and finish hone out to 3.030. This puts finish bore at around +/-.0005. You can call Anthony @ WSM at 1-866-417-4072

Sorry as you will be lucky to pick up 2 mph, it takes about 5 hp to pick up 1 mph.. To pick up that much you need to find a 78-81 3 cylinder short shaft 75hp or a older Stinger 70-75hp.

Thanks Faztbullet, Great info. I may end up looking for a much bigger motor for the boat later. I've got my 14 year old son helping with the rebuild, so no matter what the outcome is, we have a cool project.

I always thought this johnson 35 only had about 1/2 the power it should, so a 10-15 hp increase seemed feasable. I have a 10 ft hardbottom zodiac that will scream with this motor on it if all else fails.

 

[58rude]

Re: 1981 35 horse Johnson worth rebuilding?

For sure a cool project too do with your son. He will never forget it. Just get your parts first and machine second. Have fun and Happy Holidays.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Making progress here. The pistons showed up, and I made a couple calls to the piston manufacturer, and the dealer that sold them to me. What I took away from the conversations is that in the outboard industry they manufacture pistons to fit a specific bore size instead of boring cylinders to fit a 3.030 piston for example. The two pistons skirts mic'd at 3.027, and 3.0265. The recommended finish bore is 3.030, which would give me .003 and .0035 clearance. We ended up honing one cylinder an extra .0005 to end up with .0035 clearance on both cylinders.

Assembly was going well, pistons in, and then I found that I have the wrong center main bearing. Bummer. So now I wait for the correct bearing to be shipped.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Here's something I'm hoping some of you guys have had some experience with. There are 3 gaskets that came in this kit for the exhaust cover. Two of them get used, and there are two different styles.

There is an open chamber in the block next to the exhaust port. There is also a bubble in the exhaust plate (pictured farther down) that appears to allow exhaust to pass in and out of this chamber. The gasket that you see in this picture is the one that I found installed when I disassembled the powerhead.

Not sure what the purpose of that chamber is, or which gasket to use. It looks like one of the gaskets fits the block better, but it will close off that extra exhaust chamber. Anyone have any input on this?

On the left is the exaust plate which gets sandwiched between the block and the exhaust cover- which is visible in the background.

 

[jasper60103]

Re: 1981 35 horse Johnson worth rebuilding?

Badburn,
I have no experience rebuilding motors, but I have the OEM service manual for your motor. FWIW, the manual only shows a gasket like the one you took off the motor. Hope this helps.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Badburn,
I have no experience rebuilding motors, but I have the OEM service manual for your motor. FWIW, the manual only shows a gasket like the one you took off the motor. Hope this helps.

Thanks jasper. There isn't much on the exhaust cover in the manual I have here, I think it's an OEM one. Lots of other good info though. Any other thoughts on the function of that extra chamber??

 

[jasper60103]

Re: 1981 35 horse Johnson worth rebuilding?

Thanks jasper. There isn't much on the exhaust cover in the manual I have here, I think it's an OEM one. Lots of other good info though. Any other thoughts on the function of that extra chamber??

Sorry, but I have no idea. I will defer your question to the pros.

 

[tx1961whaler]

Re: 1981 35 horse Johnson worth rebuilding?

The two gaskets on the left in your picture are the exhaust cover gaskets

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

The two gaskets on the left in your picture are the exhaust cover gaskets

Good call. I'm going with those two gaskets since the other style is not pictured anywhere.

About a month has gone by while I have been waiting for TSM Performance to ship the correct center main bearing. While I did get all the correct parts eventually, and I think the price was fair, it has been a long process of frustration and phone calls not returned. :facepalm: Moving on.

Crank is in, rods connected, and crankcase is sealed and bolted together. Exhaust and intake covers installed, everything is going together nicely.

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Finally picked up all the last minute stuff, had to surface the head to clean it up. Bolted the head on with no gasket to check piston to head clearance. Found a couple spots that were pretty tight, and had to do a little clearancing with the die grinder. This thing went together in a snap after that.

My son setting the powerhead in.

All bolted in and ready for the head, wiring, carb, hoses, etc.

A little testing before we try to fire it. Everything appears to be working properly.

It turned over maybe once or twice and fired and ran perfect. It has never sounded this good and my son is so stoked that he can hardly stand still. He's ready to head to the lake tonight in the dark. Maybe this weekend.............

So the answer to the question -1981 35 horse Johnson worth rebuilding?
I'd say yes. I think I have about $400-$500 into the rebuild. We learned a ton while doing it, and hopefully have a motor that will run for many years to come.

 

[samo_ott]

Re: 1981 35 horse Johnson worth rebuilding?

Excellent. Also well worth the price in bonding. My boy's only 6 but I could see a project like this being great later on.

 

[jasper60103]

Re: 1981 35 horse Johnson worth rebuilding?

^^^ I agree. Great bonding experience and great ending. Be sure to post back on how the lake test goes.

 

[jbjennings]

Re: 1981 35 horse Johnson worth rebuilding?

Very nice! I'm sure you will get your money's worth out of that motor.
I like the hard indicator stream, too. Glad you posted results.
I'll bet your son never sells that motor!
Happy boating,
JBJ

 

[Mas]

Re: 1981 35 horse Johnson worth rebuilding?

Nice job!!! That's gotta feel good!!!

I like your "spark gap" tester...what's the brand?

Mas

 

[Badburn]

Re: 1981 35 horse Johnson worth rebuilding?

Nice job!!! That's gotta feel good!!!

I like your "spark gap" tester...what's the brand?

Mas

I can't remember the brand, but search ebay for a spark tester. I got it on ebay, it was only about $8 if I remember right.