TOPIC: Hot Rodding a Fat Fifty, a lesson

Thanks for taking the time to explain all of this! I was looking around on marineengine.com and saw the reed and cage assemblies were $44 each, 4 required and the heads were $100 each, plus the covers and gaskets, if bought at full retail, it appeared as though it would end up being $500-$600 all together. Granted, ebay is our friend, and I sure won't be paying full price for all of this, but if I can save $ somewhere in the engine, that's more for other parts somewhere else. so, I ask questions. I really do appreciate your patience. Thanks again!

Yeah check Ebay. That's where got my heads from 39.99 for both. Don't feel bad at all, questions are good that's how we learn and that's why we make these posts.

Bob

Hi I see you are looking for heads for your motor. I have a 59 fat fifty. I am parting out. I could sell you the heads fairly cheap. Let me no if your interested.

i've managed to score a complete (supposedly running and recently tuned up) 1965 evinrude 60hp motor! so now i should have all the parts i need. the question i have is: are the reed assemblies and heads the only things i should swap out? i didn't know if the ignition components, carbs, etc would be better on the '65 too.

No real difference in the carb that I know of. Not sure about the ignition system, don't think there's any real advantage but some of the experts can chime in here.

Bob

why not swap powerheads??????????

That's also a consideration at this point. I'm not attached to the '58 for any reason. Didn't know if i'd get better performance/economy by swapping parts around though.

would have to recheck cylinder size etc. but the 65 should get better power and economy than the 58....the 58 is a way cooler looking motor and is manual shift which i like better in a classic....sorta like a 4 speed is more fun in a 56 chev....i would put the 65 powerhead in the 58 rather than swaping heads and valves....john

Take the front & rear pans off of the Fatty and bolt them onto the later engine. Then the hood will drop right on. You will have to use the wiring harness and junction box from the fatty as well. Don't mess around with the fifty if you have a newer engine. There are major differences in the lower unit and the motor bracket. The newer engine is a better design. However, if you can find a nice, 75, 80, 85, 90, or 100 - do the same thing and just use the hood.

The lower unit on the '65 evinrude is dissassembled. the PO took it apart while looking into possible bad bearings. Plus, it's a short shaft, and I need a LS (not sure if the parts would be interchangeable - haven't looked yet). If I'm better off using the powerhead from the 65 though, I'll run that route. How are the 60hp models on fuel consumption? Any recommended mods to make it better?

Now if you don't want the short shaft just the shaft I could use it. Let me know.Post some pix and I might have a long shaft for you.
Mike aka the pirate

Bruce -

you're saying that the powerhead from the '65 isn't compatible with the lower end on the '58?

No should fit but it would be easier to just change the cowl over. Bruce you can correct me if that's not what you meant.

Bob

i understand the cowl cover swap idea and, under different circumstances, would proceed that direction. the LU on the '65 is in shambles and is a SS and i need a LS anyway. swapping the powerheads, if possible, is going to be a better option for me at this point. if they're not compatible i can still use the parts off of the 60hp motor to hot rod the fat fifty.

As a side note: sorry to have hijacked the thread!

No biggie. We'll have to double check with Bruce or some others, the powerhead should just bolt up and the little bit of extra power shouldn't affect that lower since it's pretty hefty and darn near bullet proof.

Bob

Well everybody I finally made it out to the lake with the new reed valves, the fatty runs awesome only thing is was smoking a lil' out the exhuast I'm thinking it was due to the fact my gas was over a year old lol and when i mixed it with new gas put too much oil in it. I just have one question hopefully i can get some feedback. Since I replaced these old style reeds with new style do I have to lean out my carbs or maybe even make them run richer? Also is there anything that can be done to get rid of the sheen of oil/gas, that gets dumped out the exhaust and goes in the water? seems like it is such a waste and doesn't look like it would help water quality. Any info would be greatly appreciated. Thanks for all the helpful tips from everyone out there, especially Bob and Bruce thanks again.

Glad she's back on the water and running good. As far as adjustments, I just re-tweaked the low idle and high speed adjustments again once back on the water, according to the factory procedures from the old manual I had. The gas/oil slick is pretty much the nature of the beast with these things but I vaguely remember reading something somewhere about some kind of hose back to the tank. Others smarter than me can jump in here.

Bob

Was wondering if the 1964 60hp is the same as the fat fifty? What i mean as for as the same, Is the fuel consumption the same? Is the 10 hp difference something u can tell while in the water? Also is it more economical? Does it throw the unused fuel/oil out the exhaust also?

The later Johnson/Evinrude/Gale/SeaKing V4 60HP engines are a slightly modified and improved version of the Fat 50.

The differences in the 60 are:

A slightly lower piston dome with a smoother profile - to fit the new "power dome" heads

"power dome" Heads with full water jacket cooling. The combustion chambers on these were contoured to fit the piston crown more tightly. The Fat 50 had open chanber heads like the Big Twins had.

New V block & "finger" reed system replaced the horrible "daisy" reed system of the Fat 50.

Minor revisions to the carburator - mostly, a new design throttle plate cam, and some air/fuel circuit tweaks.

The Fat 50 "football" lower unit was promoted as the "heavy duty" gearcase and came on the "commercial" edition engines. It was also available on certain other models. The "jetstream" bullet nose lower unit became an option, and was standard on some models.

In 1968, the "60" got upgraded to 65 HP. This engine had CDI solid state ignition that was no longer belt driven. I suspect that the exhaust ports may have been enlarged slightly - helping to give the 5 extra ponies.

All incarnations were 70.7 cubic inch displacement, and used the same crankshaft and engine block. The Starflite/Seahorse 75hp of 1960 used larger cylinders & pistons to produce the additional 15 ponies from 89.9 cubes. The 75 block was the same as the fat 50, excepting that the cylinders were larger. Not simply a Fat 50 bored out. The cylinders were actually cast larger to create more cubic inches. The heads and pistons will not interchange with the 50,60, or 65hp engines.

The 75hp carburator had fixed main jets, and the venturis were slightly enlarged.

The 75 gradually was boosted to 80hp then topped out at 85hp in 1968. These power increases were due to minor tweaks in porting and CDI ignition in 1967 and 1968.

All incarnations of the 1st generation 2 barrel carb engines had serious problems with fuel waste. This is because the crankcase volume was way, WAY too high. The 90 and 100 hp engines used a redesigned crankcase and block to substantially reduce the internal volume. These engines produced far more horsepower from the same displacement. The also ran better, used MUCH less fuel, and did not dump the raw fuel the way the gen 1 engines did. They are a far better engine design.

The Gen 1 engines had problems with raw fuel making puddles in the massive crankcases. This would make the engine load-up and foul plugs. A pair of small reed valves were employed to constally "vacuum" the unburnt fuel from the bottom of the crankcase. This fuel was then simply piped into the exhaust tower, just below the powerhead. Where did the fuel go? You guessed it - straight into the lake.

Just so you know - Mercury engines used a similar "weep line" system to keep their inlines from loading up with fuel. It too, drained right into the lake!

So the 1964 60hp also seeps unburnt oil and fuel out the exhaust? If it does well probably just leave the fifty on being that a put reeds from a 64 60 hp