Evinrude H.P. upgrade?

[kucobra]

I have a '78 Rude 25 h.p. short shaft electric start. I was told that the 25 could be converted to a 35 h.p. and that they were the same except for bigger carb (jets). Anyone have knowledge of this? If so how is it done?thanks

 

[beau123]

Re: Evinrude H.P. upgrade?

Do a search in these threads, I believe this has came up before.

 

[F_R]

Re: Evinrude H.P. upgrade?

The carb probably is larger (bore/venturi). Just changing jets will only give you a very lousy running motor. There are other differences too. It would take a search of the parts catalogs to discover what they are. There is a good chance that one of them is a balanced crankshaft on the 35, but I don't know because I'm not going to spend the time looking. Check the price of a complete 35 carburetor and you won't bother going any further either.

One thing for sure, the 25 and 35 that year use different lower units. Even if you were to swap the complete powerhead you still would not get the same performance as a 35 because you don't have the better perforning lower unit design.

 

[WillyBWright]

Re: Evinrude H.P. upgrade?

Different carburetors (not just the jets), different gearcases, different midsections, different intake manifolds. Probably more.

 

[kucobra]

Re: Evinrude H.P. upgrade?

Ok thanks for the replies, I saw some posts on a 25 to 30 upgrade but I was wondering about the 35, I didn;t know there was that much difference. think I'll just buy a good 35 or 40 on hang on her.
thanks again

 

[bigtwin]

Re: Evinrude H.P. upgrade?

I've noticed there are alot of differant parts between a 25hp and a 30hp, (carb., intake, throttle cam, ect...) however after looking through the parts catalog several times, I can't find any differance between a 30hp and a 35hp.
One day, while I was visiting the good folks down at T/C Outboards, I ask them if they knew what the differance was, they told me, that after machining the "block" they would inspect and measure each block (cyl. bore dia. and roundness, port locations and size, ect...) and the blocks with the tightest tolerances were sorted out to become 35hp motors.
This makes sense to me, how often do we hear about two identical motors off the same asembely line, one motor goes like a bat outa hell, while the other just goes.