The story of two motors - 75 Johnsons

[flyingscott]

The original thought was to use this motor while he did a tear down of the new one. He doesn't want to use it long term, unless I missed something. So the amount of time, effort, money may not be something he is willing to invest.


Its something that might need to be done. Won't know until he cracks the case.

SHSU

I have never seen anyone blance a 2 strk crankshaft. That is only a racing thing. If there is that much damage it must be replaced.

 

[flyingscott]

@SHSU That is correct. Id like to stay on the water for a few months until the end of the season. The ugly duckling is not worth rebuilding - yet. She has so many issues, and the UD would need balancing of some sort the way she shakes too…. Was told that by a guy at the docks who knew a lot more than me. The stinger IS worth rebuilding since I have the head off and she looks great internally, also looks great externally.

Ok, thanks for the information guys. Looks like the powerhead (assuming now thats at minimum the head and pistons) needs a rebuild, and the cost is around $1000. Im guessing more people dont do that because its a lot of money to put into an older motor - a labor of love, not wise spending. Thats a decent down payment on a brand new motor but I get it.

Two motors, two options.
1- Rebuild ugly duckling, cant say I want to polish a turd.
2 - Cannibalize the UD as needed and rebuild the stinger from scratch - more inclined to go with this route.

So… heres the plan. Going to clean the carbs and change the seal/oil of the UD. That should (barely) keep me on the water and it preserves future parts for the stinger. I get it - not great for the UD, but shes called that for a reason. The Stinger is the motor worth building from the ground up and doesnt need a full powerhead rebuild (from the looks of it) - she just needs a revival. Once the stinger is revived, I will look at rebuilding the UD’s powerhead.

My question now is, where do I start with the stinger? I have almost complete gasket kits, minus what ive used, for these motors and the stinger had been sitting in the desert for years. Id be surprised if any of her gaskets are still good. Ill get started on her as soon as the carbs and seal are done on UD. Just dont know where to start. My previous experience with these motors has been bolts break easy and are hard to get out - so tips and tricks to make life easier and not cause bigger issues would be appreciated.

I did borrow the head cover off of the Stinger for the UD so I will find, a hard to find, replacement for the Stinger. Need another anyway to have 2 motors.

Side thought - a guy was selling a boat and trailer with 2 running 75’s and a parts 75 for $1500 obo…. For that powerhead rebuild cost I could have a fleet of motors lol.

Or is it a fleet of junk?

 

[Moserkr]

Or is it a fleet of junk?

Quite possible lol. Sticking with what I got - dont need more issues, especially with my wife.

 

[racerone]

You have to put the idea of balancing the crankshaft away somewhere.----It just is not needed on a 45 year old motor !!!

 

[RBoyd1971]

Give that stinger a tune-up and run her. That ain't a 70s and 80s Mercury we're talking about. I've pulled them Johnyrudes out of the woods after sitting 10 years and had them running and on the lake in a couple of hours.

 

[Moserkr]

@RBoyd1971 Think all her gaskets are still good after at least a 3 year stint in the desert? Or do you find out by just running it.

 

[RBoyd1971]

I would imagine they are fine. Check impella, change gear case oil, clean carbs, change and gap plugs. Make sure the fuel line and plug wires are ok and run it. Personal I would want the original head back on it. Get you a used one off of eBay for the UD motor.

 

[RBoyd1971]

That stinger has low hours on it. Either that or the owner took very good care of it. No way would I take it apart for a rebuild and you haven't even heard it run.

 

[Moserkr]

I would imagine they are fine. Check impella, change gear case oil, clean carbs, change and gap plugs. Make sure the fuel line and plug wires are ok and run it. Personal I would want the original head back on it. Get you a used one off of eBay for the UD motor.

Thanks Rboyd, the original head thought I definitely agree with. All wires look good inside. I will do the other recommendations and start her up. Yes, it looks extremely clean for such an old motor.

One question, since it doesnt have a control box, how do I stop it once I get it started? I know I can run power directly to the starter to start.

 

[RBoyd1971]

I would unhook the fuel line, let it run until it just starts to miss, then manually close the choke. It should die. The black and yellow wire coming from the power pack kills it as well when grounded. Should be terminal 6 which is the bottom left wire.

 

[Moserkr]

Back in the saddle after a vacation and catching up on life.

Where we left off…. I was polishing a turd and thats done now. Ugly Duckling got new lower prop shaft seals, and her carbs rebuilt. I broke a plastic gas fitting on the primer solenoid cover so will replace that when it gets here. Thats as far as Im going with this motor until I find a replacement cylinder head cover. Going to take the stingers off of it and put it back where it belongs. With the new cover for the UD, I will take pics of her insides to see how bad the cylinders are scored. Then can decide what to do with the UD. I am listening to the advice that this motor will need to come apart for a rebuild IF its deemed to be rebuildable. Before that happens though, the stinger will be tested.

The stinger will get her head cover back and I found an ignition with choke/keys at the local napa that should work to make firing her up easier. The plan is to see if she runs or has issues. The lower needs new fluid and possibly seals, definitely will replace the water pump.

Got some ordering to do and another short trip coming up so none of this is going to happen fast. Hoping for a test of the UD in its current condition once that piece I broke comes in. After that its on to the stinger plan.

 

[Moserkr]

Ugly Duckling is alive!! Cleaning the carbs really woke her up. Sure she has issues, but she ran today like it was her last chance to prove herself. And she took gold!! Fixed some gas leaks too in the fuel lines that run to the carbs. Other than that, no issues whatsoever with UD. She fired up on demand with no starter fluid (helps when I follow starting instructions). Idled great. Accelerated good - would stall if i just slammed it down, but once she had a few RPM’s going I could let her eat. Very happy with her performance, she started and ran better than Ive ever seen. At WOT she ran faster than Ive ever seen on this boat before. I had an issue with weight distribution in my boat build but thats another story. It prevented me from staying on plane at WOT but ill fix that.

Plan is still the same though in the end - fix up the stinger and put it on the boat. But Im happily on the water again so no complaints. Going to order service manuals and a new cylinder head cover then get to work. May be a few months though since its just about hunting season, so consider the stinger a winter project now. Happy boating!!

 

[Moserkr]

Man, reading that last post reminded me of the trip after it. UD started up great, was warming up as we got to the next arm of the lake, then boom, faceplant!! She started surging, died, and wouldnt get back up. Finally I was able to get her going and we crawled back to the dock at maybe 5mph. Would not let me go any faster.

So winterized her and have no had time to work on anything until now. Yesterday I bought a factory service manual for UD. Today, I started off by checking two things. First, fuel system check from the fuel tank to the motor connection. Strong flow through the filter and out the end. Plugged her back in and then check compression.

Last year compression was:
#3 - 99 Bottom
#2 - 100 Middle
#1 - 107 Top

This year compression was:
#3 - 126 Bottom
#2 - 129 Middle
#1 - 135 Top

The only thing I did different was set the idle lever to starting position. Have not run the boat since I winterized it either. Not sure what cause the jump in numbers. Im happier none the less despite her less than stellar performance last tine out. Any ideas on how that happened, Im all ears.

I rebuilt the carbs last year too and Im sure they still have issues due to the old rusty fuel tank she used to drink from. Since I have the service manual now, Im going to do em right this time and see how she reacts. Then continue with trouble shooting and maintenance.

Finally, around xmas last year, I bought a spare head cover for the motors. I was short 1 and now I can happily say Im able to build both motors!! Going to see if I can iron out the issues with the UD first before I try to do the stinger. Either way, its nice to know I have the proper pieces to complete the set. Parts arent getting easier to find!!

 

[racerone]

They built a lot of those motors so parts are not that hard to find.----First think I would check is the flywheel key.