1956 Johnson 6hp versus evinrude 6hp pros and cons

[Evinrudej]

Hey guys so I’m a big Johnson/evinrude 6hp fan but I have the opportunity to buy a really nice 1956 7.5hp or a 6hp and I don’t want to buy both unfortunately. I’ve never owned a 50’s model Johnson/evinrude so this will be a first and I don’t know much about them other than their weight. Is the 7.5 worth the buy over getting another 6hp. Is it more powerful than a 6hp? Better top speed? Quiet? Hard to work on? I’ve always loved the design of the 56-57 models. Any more info would be great thanks.

 

[Crosbyman]

two hose tanks to consider on the 7.5. if ok fine if not you can modify to pump ..... great motors
6hp fisherman is fine also nice motor
do compression tests on both and go for the better of the two

otherwise check for mecanical and amount of TLC it got for 50 + years.

"another 6hp" ...so do you have one alrerady ?? so go 7.5hp

bible for 7.5hp
https://watercraftmanuals.com/outboard/johnson/manuals/johnson-302231.htm

 

[Evinrudej]

two hose tanks to consider on the 7.5. if ok fine if not you can modify to pump ..... great motors
6hp fisherman is fine also nice motor
do compression tests on both and go for the better of the two

otherwise check for mecanical and amount of TLC it got for 50 + years.

"another 6hp" ...so do you have one alrerady ?? so go 7.5hp

bible for 7.5hp
https://watercraftmanuals.com/outboard/johnson/manuals/johnson-302231.htm

Thanks for the info. Is there a noticeable difference in speed?

 

[jimmbo]

Thanks for the info. Is there a noticeable difference in speed?

Depends on the Boat, but not much

 

[F_R]

Think of it this way. At one time the 7.5 and 5.5 were sold side by side. A 6hp is basically the same motor as the old 5.5. IF the 7.5 will plane the boat but the 6 cannot there will be a considerable increase in speed.

 

[Crosbyman]

a weak 7.5 is no better than a strong 6 You can't realy tell beforehand ...don't be to hung up on a few mph just enjoy the ride.

 

[racerone]

The 6 has needle bearings on the crank journals for the rods.----Run on 50:1 mix.----The 7.5 was marketed for 56 / 57 / 58 and they are a great running engine as well and run on 24 :1 mix.----The 7.5 has the slip clutch in the gearcase and better bushing above the pinion.

 

[oldboat1]

If the 7 1/2 has an access port on the side of the leg, removal of the powerhead isn't necessary to service the water pump (two models in '57. Check '56.) Powerhead removal isn't as daunting as it might sound, but disconnecting the shift rod in the leg is easier.

The 7 1/2 definitely has a bit more power than the 5 1/2 (6), and idles down just as smoothly. Needs a richer oil mix as mentioned earlier.

 

[racerone]

Are you 100% sure that the 7.5 has a plate to separate shift rod ??

 

[oldboat1]

Sure about the '57 model, and suggesting the poster check on the '56. (may apply to Evinrude only)

 

[racerone]

Need to review your parts books.----That exhaust housing was used from about 1954 to 1979 on the 5.5 / 6 / 7.5 HP -----Just looked at a 54 and a 79 in my parts shed.-----No plate on them !!

 

[oldboat1]

Thanks for the note -- will need to get out to the workshop, clear a path, and check.

 

[Evinrudej]

Think of it this way. At one time the 7.5 and 5.5 were sold side by side. A 6hp is basically the same motor as the old 5.5. IF the 7.5 will plane the boat but the 6 cannot there will be a considerable increase in speed.

Well right now my 6hp won’t plane the boat without some weight in the front so I’d hope the 7.5 has a little more power to plane the boat out better and thus increase my mph atleast by 1-2. I’m currently getting 11mph with weight added to the front with the 6hp.

 

[oldboat1]

Need to review your parts books.----That exhaust housing was used from about 1954 to 1979 on the 5.5 / 6 / 7.5 HP -----Just looked at a 54 and a 79 in my parts shed.-----No plate on them !!

Checked the workshop storage, and have one 7 1/2 left -- no access plate on it ('57 model). Could be a phantom memory of a 76 yr. old brain.

 

[oldboat1]

Well right now my 6hp won’t plane the boat without some weight in the front so I’d hope the 7.5 has a little more power to plane the boat out better and thus increase my mph atleast by 1-2. I’m currently getting 11mph with weight added to the front with the 6hp.

Open boat -- no flooring?

 

[Evinrudej]

The 6 has needle bearings on the crank journals for the rods.----Run on 50:1 mix.----The 7.5 was marketed for 56 / 57 / 58 and they are a great running engine as well and run on 24 :1 mix.----The 7.5 has the slip clutch in the gearcase and better bushing above the pinion.

Off topic question here but on my 1974 6hp I’ve been having this issue with a slight hiccup. Ever since I bought it I’ve had this issue. It starts up fine and idle down smooth but every so often while running either at mid throttle or at idle it will have an occasional hiccup. I’ve cleaned and rebuilt carb with oem kit. Set low speed need needle correctly which I’ve never had a problem with any of my other motors so that’s fine. I’ve cleaned and adjusted points. Ignition is still as I bought it but coils seem to look fine no cracks on the top. There is some evidence that the fly wheel was rubbing against the coils at some point but I don’t believe it is anymore. One issue I’m having now is primer bulb not staying firm but it seemed to pump okay still. Took the fuel pump apart and noticed some kind of brownish reddish sediment so I’m going to rebuild pump. Has new spark plugs as well. Any ideas for this hiccup?

 

[Evinrudej]

Open boat -- no flooring?

V hull about 11.6ft with 3 seats.

 

[oldboat1]

If flooring, may be carrying considerable water weight in foam underneath.

Your shift dog may be in need of replacement (the hiccup). Often described as feeling like you ran over some submerged object.

 

[Evinrudej]

If flooring, may be carrying considerable water weight in foam underneath.

Your shift dog may be in need of replacement (the hiccup). Often described as feeling like you ran over some submerged object.

It’s not a gear case issue. It’s more like a slight mis fire that happens very occasionally. It happens both in gear and and in neutral.

 

[racerone]

Run with timing light and see if you can pinpoint top or bottom cylinder.-----Inspect bottom of the coils.----Test the coils .----Replace condensers.---Replace plug wires with 7 mm metal core ones.----Primer bulbs do not need to be hard once motor is running !