33 hp block

[Woodstock60]

I have a 1968 33 evinrude. while stripping parts off a 1955, 25 hp johnson I noticed the block was the same. I cant find info on the 1955. Does anyone know what the differances in the blocks are. The 33 has a fair amount of damage where she bolts to the exhaust housing. Was thinking I could either swap out as is or rebuild with good block. Any advice would be appreciated, Thanks, Ronnie

 

[F_R]

Re: 33 hp block

Oh they look similar, but actually there are a lot of differences. In the first place, the 25 is 2-7/8" bore and the 33 is 3-1/16" bore. They have different bearings, cylinder heads, crankshafts, and flywheels. And more..

Just an interesting tid-bit of info on the 25: They made a mid-year change in 1955, "improving" it to the point that they created a lemon. An awful lot of powerheads got replaced under warranty that year. In the 1956 30hp, they "un-improved" it back to the way it was in the early '55s.

 

[Woodstock60]

Re: 33 hp block

Thanks, That makes my desition easy, I'll stick with what I have on my 33 and keep the 25 for parts for my other 25. I am curious what was the mid year change? I have a running 1955, 25 seahorse, which has had its share of issues and I'd like to find out what makes it junk, and if mine has these changes. Thanks Ronnie

 

[F_R]

Re: 33 hp block

Thanks, That makes my desition easy, I'll stick with what I have on my 33 and keep the 25 for parts for my other 25. I am curious what was the mid year change? I have a running 1955, 25 seahorse, which has had its share of issues and I'd like to find out what makes it junk, and if mine has these changes. Thanks Ronnie

Early models had a carbon seal on the bottom main bearing. Then somebody decided that was too expensive so they changed it to a common lip-type seal, part number 303804. The 303804 was a crappy seal and was lucky if it lasted a year. When it failed, water was ingested into the lower main bearing and circulated throughout the powerhead, totally destroying it. Wonder if that genius that made the change got a bonus for saving the company money? Anyhoo, they went back to the carbon seal after replacing a bunch of powerheads. To retrofit an existing 303804 requires a different crankshaft and main bearing.

Same goof-up was made on the 15hp (picture)

 

[Woodstock60]

Re: 33 hp block

Thanks for that info F_R. It looks like mine has the carbon seal, I certainly hope it does. I'm going to start a new thread on this motor and post some progress pics. again thanks

 

[Minnow00]

Re: 33 hp block

Early models had a carbon seal on the bottom main bearing. Then somebody decided that was too expensive so they changed it to a common lip-type seal, part number 303804. The 303804 was a crappy seal and was lucky if it lasted a year. When it failed, water was ingested into the lower main bearing and circulated throughout the powerhead, totally destroying it. Wonder if that genius that made the change got a bonus for saving the company money? Anyhoo, they went back to the carbon seal after replacing a bunch of powerheads. To retrofit an existing 303804 requires a different crankshaft and main bearing.

Same goof-up was made on the 15hp (picture)

F_R do you know if the part number on the carbon seal is the same as the part number for the lip-type seal? My parts catalog shows part number 303804 for my FD-10L sn1407586