Converting 80's 6hp to 8hp?

[Wee Hooker]

Sorry if this has been asked before but I've searched a few times and can't find the answer. I have a 85' ( if memory serves, Johnson 6 hp which isn't a beauty queen but has very low hours. I'm thinking she'll be due for a carb rebuild soon and was wondering what it would take to bring it up to 8 hp ( which I know is based on the same head/motor.)
Thanks in advance.

 

[CATransplant]

Re: Converting 80's 6hp to 8hp?

I don't think it's as simple as swapping carbs...assuming you could find an 8 hp carb in the first place for a reasonable price.

However, you can go to http://shop2.evinrude.com and look up both the 6 and 8 hp models and compare parts. Look beyond the block and carb. It may have a different manifold, different reeds, and a different exhaust tube.

They made way, way more 6 hps than 8 hps in those days. Trust me...if all you had to do to go from 6 hp to 8 hp was swapping carbs, there wouldn't be an 8 hp carb to be found anywhere.

 

[CATransplant]

Re: Converting 80's 6hp to 8hp?

OK, I did the comparison for you. The crankcase and cylinder assemblies are different for the 6 and 8 in 1985 (and probably for other years as well). Intake manifolds and carbs are different, too. None of the parts are available new for the 8 hp.

Your best bet will be to look for an 8 hp that's running and sell your 6.

 

[Wee Hooker]

Re: Converting 80's 6hp to 8hp?

Thank You sir,
I assumed that since the tech specs and weight were nearly identical, that it was something simple like new jets and a few adjustments. So much for dreaming!
The 6 is fine for my current needs but I'll keep my eyes open for a nice 8. IF I could upgrade for $100-$150 or so after it's all said and done, with no weight gain, it would be worth it.