1963 Johnson QD 24 10hp revival questions

[bob1123]

Friend of mine gave me a 1963 Johnson QD 24 today. He got the motor from another guy a couple years ago and didn't know anything about it. Guy I got the motor from hadn't touched it. I was messing around with it today. No air box, but otherwise looks all there. It's been painted blue. Here's what I've done/noticed so far:

Checked for spark- motor has very strong spark.
Checked plugs- someone installed the wrong plugs. The ones in it are too long and pistons hit the plugs. Needs correct plugs.
Checked compression- have ~60 on one cylinder and ~70 on the other.

Motor was free to me. I could use a good 10 horse for some of the lakes around here with hp limits. I'm a little concerned about throwing money at a motor with compression numbers like that though. Any advice on the compression? Replace plugs, fire it up, check for water, and see what happens?

 

[racerone]

Don't think those had an airbox.------Remove bypass covers and inspect pistons and rings.-----If they look good install a new impeller.-----Check the thermostat as they are often missing or stuck open.----Change gear oil.----Go fishing.----These are an excellent / reliable / easy to maintain motor.----Refurbished one for the grandson a few years ago.

 

[kbait]

Champion J6C or NGK B6S @ .030”.

 

[Crosbyman]

Duckworks Magazine

here is a similar motor being revived

 

[bob1123]

Pulled the top bypass cover. Everything looked ok. Looks like I can't get to the bottom cover without pulling the power head. Pulled the lower unit. Has a good impeller. Noticed there wasn't any oil in the lower unit so I decided to dig into it. lower unit was full of small metal chunks. The shifter cradle has broken apart and eaten up the pinion gear. Other gears and clutch dog look ok. Lower unit is bad. Starting to think with the lower and 10psi cylinder difference this may be a parts motor.

 

[racerone]

These are in fact an excellent motor.----63 was the last year for that 10 hp model.----Lower units from the 9.5 model ( 64 to 73 ) will fit if you change out the driveshaft and shift rod.----I have taken that lower bypass cover off no problems.----One of the features of these motors is that when you take the cover off all parts are there for easy maintenance.---Light weight motors as well.----So simple that the 8 year old grandson installed a new impeller in his 1963 model 10 HP.----With a good coach of course.

 

[bob1123]

Couldn't get a great view of the cylinders/pistons. Convinced myself to try and remove the head to check it out. First two bolts I tried on the head broke off.

 

[racerone]

Parts motor.----I get those in exchange for a box of beer.

 

[bob1123]

Yeah, that's what I was thinking when I got to the lower unit. Confirmed when the bolts on the head broke off. At least I have bypass covers now if I want to convert another motor to a single line tank. I always thought the late 50's Johnsons/Evinrudes looked particularly sharp.

 

[silver_bay]

The last years of the 10hp (like yours) have heftier wrist pins (a weak point on earlier OMC 10s), and sturdier gears (tho yours didn't survive), which were a weak point after they moved from the 5-bolt lower unit (shared with the 18hp) to the 4-bolt (shared with the 5.5/7.5). If the pistons and rods survived, those are parts that could be saved and transplanted to an earlier 10hp.

 

[ct1762@gmail.com]

The last years of the 10hp (like yours) have heftier wrist pins (a weak point on earlier OMC 10s), and sturdier gears (tho yours didn't survive), which were a weak point after they moved from the 5-bolt lower unit (shared with the 18hp) to the 4-bolt (shared with the 5.5/7.5). If the pistons and rods survived, those are parts that could be saved and transplanted to an earlier 10hp.

i have a 1970 9.5hp with a good powerhead and lower ill let go for cheap haha