1973 25hp Johnson - can it be run on regular muffs?

[kgronseth]

I am looking at buying a 1973 Johnson 25hp, short shaft, electric start. I can't tell from the pics provided where the water intake is. I want to ask if I can use my regular muffs (that I use on my '81 9.9 Evinrude) to test it out in idle, but don't know if I am able to or if it needs to be run in a tank.

If anyone is familiar with this model and can let me know it would be greatly appreciated.

Thanks!

 

[hidef]

Re: 1973 25hp Johnson - can it be run on regular muffs?

You gotta put in a barrel. The water intake is in front of the exhaust port behind the prop.

 

[kgronseth]

Re: 1973 25hp Johnson - can it be run on regular muffs?

Thanks! Was there a certain year when all Johnson/Evinrude had intakes that can use the muffs or does it vary by year/model, etc.? Just curious since I'd like to by one that I can use muffs on vs put in the barrel and if I can go by a certain year as the cutoff or if I have to look at each one individually.

 

[kfa4303]

Re: 1973 25hp Johnson - can it be run on regular muffs?

I don't think they went to "muffable" motors until the late 70's-early 80's. All motors prior to that, from the 50s, 60s, 70s all need to be run in a test tank with water filled to about an inch or two below the main exhaust port on the leg because they do not have self priming water pumps. They also lack the modern "tell tale"/"pee stream" that modern motors have. Instead the cooling water is simply mixed with the exhaust and expelled out of the motor.

 

[hidef]

Re: 1973 25hp Johnson - can it be run on regular muffs?

The 1968 or 67 55 hp triple was the first OMCs to run on muffs in 1969 the 55 and up could all be ran on muffs. The smaller out boards 9.9 and up where converted over to thru the hub exhaust through the 70s and 80s. The 25 was the last of the mid size outboards to switch over to through the hub.

 

[kgronseth]

Re: 1973 25hp Johnson - can it be run on regular muffs?

Thanks all for the great input!