Replace a 5hp motor with a 7.5hp motor

[gmarshall43]

Can I replace a 1958 5hp johnson motor with a 1954 7.5hp evinrude motor? And would it work?

Thanks,
Gary

 

[dazk14]

Re: Replace a 5hp motor with a 7.5hp motor

Can I replace a 1958 5hp johnson motor with a 1954 7.5hp evinrude motor? And would it work?

Thanks,
Gary

Sure, why not. If the boats rated for it...

Or, could you be asking, can I mount a 7.5 powerhead on a 5hp mid?

 

[oldboat1]

Re: Replace a 5hp motor with a 7.5hp motor

as above, not sure what you are asking -- but think you probably want to switch powerheads. First thing to check would be the bolt pattern for each (got to believe you could not interchange). What's the condition of each of the motors? Maybe could get one or both up and running on their own. Maybe lower unit work on, say, the 7 1/2. Does the five have a blown powerhead, maybe? guessing here.

 

[boobie]

Re: Replace a 5hp motor with a 7.5hp motor

Need more info ??????

 

[nwcove]

Re: Replace a 5hp motor with a 7.5hp motor

even if it will bolt up, the 7.5 powerhead will not fit under the 5.5 cowl.

 

[HighTrim]

Re: Replace a 5hp motor with a 7.5hp motor

Wont work at all, under any circumstances. Send to me for proper disposal.

 

[gmarshall43]

Re: Replace a 5hp motor with a 7.5hp motor

Yes, the idea was to mount the 7.5hp on the 5hp unit. I haven't checked out the bolt pattern but I wasn't sure if the 5hp lower unit would support the 7.5hp motor. I also didn't take into consideration that the cowl would not fit with the 7.5hp motor under it. I know these older motors had interchangeable parts but wasn't sure if I could switch power heads seeing that its only adding 2.5 more hp. The 5hp motor is no good but the lower unit still works and the 7.5hp motor is being sold by its self and was told it is a good working motor. Thanks for the repsonses.

Gary

 

[Chinewalker]

Re: Replace a 5hp motor with a 7.5hp motor

The 7.5 powerhead will bolt up, but won't work. '55 & prior used a slightly different water pathway compared to '56 & later. This holds for the 5.5 powerheads, too. You would need a 5.5 powerhead from '56 to '58 to get your motor going again.

Plus there's the cowling issue as mentioned previously.

 

[oldboat1]

Re: Replace a 5hp motor with a 7.5hp motor

already have these motors, or thinking of buying them? If buying, can buy the 5 1/2 as a parts motor -- might come up with a powerhead for it at a later date. Could buy the 7 1/2 as a potential runner. Changes issues if you are shopping. You will want to get them cheap, and check them out as best you can before buying -- compression on the 7 1/2, maybe on the 5 1/2 if there is any life. Spark check maybe, but can fix ignition. See if you can get some history. Did I mention buy cheap? Both are parts motors at the moment.