Topic: 1958 Johnson 7.5 oil mix – Antique Outboard Motor Club,Inc

This topic has 10 replies, 7 voices, and was last updated 8 years, 9 months ago by amuller.

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October 20, 2016 at 4:41 pm #5535
hdted
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From everything I read on the internet 1958 Johnson 7 and a half HP motors are meant to run on a 16 to 1 oil mix. I have several other Johnsons and Evinrude motors and all are 24 to 1 mix. My question is can the 7.5 be safely run on 24 to1 so that I can run all of them on the same tanks. Thanks, Ted
October 20, 2016 at 4:54 pm #46195
20mercman
Participant
The Fleetwin and Johnson 7.5’s were not as modern as the other motors and they still didn’t have needle bearings on the rod bearing connections. You will get a huge swing of opinions on this topic, (kind of like politics), but they do need more lubrication than the 24:1 motors. You could probably get away with it, but why risk it? All of the input on today’s oils being significantly better than ANYTHING from back in the day are all true, so that is why you could probably lean it out some, but be careful. It is only the rod bearings that are the reason for the rich mixture on this motor. The pistons could run forever on 24:1 or leaner and not have a care in the world.

Steve
October 20, 2016 at 6:03 pm #46202
fleetwin
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US Member
No argument here….16:1 for the 7.5hps with plain rod bushing….
October 20, 2016 at 6:07 pm #46203
Mumbles
Participant
And the 5.5’s.

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October 20, 2016 at 6:46 pm #46205
PugetSoundBoater
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quote Mumbles:

And the 5.5’s.

I didn’t know Einstein was into outboards, learn something every day

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson
October 20, 2016 at 6:52 pm #46206
outbdnut2
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US Member
quote pugetsoundboater:

quote Mumbles:

I didn’t know Einstein was into outboards, learn something every day

Einstein actually is somewhat into boating (LOL):

https://www.yelp.com/biz/einsteins-ship … ntgomery-2
October 20, 2016 at 9:30 pm #46211
hdted
Participant
!6 to 1 it is. I’ll just mark one tank for 16 to 1 so I won’t get them mixed up.
October 20, 2016 at 9:58 pm #46213
PugetSoundBoater
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quote hdted:

!6 to 1 it is. I’ll just mark one tank for 16 to 1 so I won’t get them mixed up.

I mark all my gas cans , boat and otherwise with date filled and ratio . I have several tanks and gas cans ,so if they weren’t marked…" what’s in here"

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson
October 20, 2016 at 10:50 pm #46215
amuller
Participant
Am I correct that up through 1977 the little 4 hp twins were plain bearing motors and ran at 50-1?
October 21, 2016 at 11:51 am #46244
fleetwin
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US Member
quote amuller:

Am I correct that up through 1977 the little 4 hp twins were plain bearing motors and ran at 50-1?

Yes, you are correct, unfortunately….I would recommend running those engines at 24:1 though….
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