power head or exhaust plates

[keithm1961]

I have a 1976 85hp johnson and a 73 evinrude 115, I was planning on swapping the power heads which I understand should take about an hr, but I was told that I could swap the exhaust plates and this would get rid of the restriction and boost the 85 hp output, is that true? if so would I be better off doing that or the powerhead swap? opinions

Thanks
Keith

 

[emdsapmgr]

Re: power head or exhaust plates

The powerheads will swap. Both engines are flatback models and neither uses the bubble back high performance exhaust system. It was the 135 hp model which had the exhaust bubble standard from the factory. You won't find any gain in hp due to the elimination of any "restriction." The real reason to swap the powerheads is due to the displacement and carbs. The 85 hp engine is only a 92 cubic inch block. The 115 is a 99.6 cubic inch block. Along with the larger cubes, the 115 may have larger throated carbs and should make noticeably more hp.

 

[Gary H NC]

Re: power head or exhaust plates

Agree,The power head swap is the only way to go.
Be sure to use a new power head to adapter plate gasket...

On my V-6 i can have the power head off in about 30 minutes..