55hp powerhead 65 leg ???

[aussiemik]

hi ive got a chrysler 55hp o/b with a worn l/u wondering if the leg & l/u off a 65hp will fit on my motor. the wrecker said it would fit but im not so sure,any one tried this ???

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

hi folks i got a 65hp 659h8b from the wreckers to try and fix my 55hp 559h8k with a bad box. ive pulled them apart to try and put the leg & box off the 65 on the 55 so far so good. i have no manual but it looks like the exhaust pipe is supposed to seal in the top part of the leg to hold water around the outside mabye for cooling then drain down two plastic tubes rising up with little holes in them??? can normal silicon be used for this ??? also the rubber tube that runs between the manifold on the top carby and the bottom bearing housing is this to recirculate the fuel back ive read on other posts about puddle drains is this something like that??? mine was blocked so i blew it out with air hoping it wont leak so much fuel down the leg now, im going to replace the two seals and o ring while im at it. last but not least the wrecker said that if i put the carbys off the 65 on my 55 it will make my 55 equiv/ to 65 that they are the same bore & stroke is he pulling my leg or what?? this is my first outboard but really enjoy working on this and would really appreciate some info off someone that knows what their talking about thanks!!! mick

 

[eurolarva]

Re: 55hp powerhead 65 leg ???

I have been avoiding this post because I really dont know. First off the 55HP you have is from 1979. I was unable to find the 65 model number you mentioned. The closest one I could find was 659H8 and by looking at the gear housings I would say no. It will not fit. It looks as though everything including the where it locks up to the motor leg is all wrong.

 

[steelespike]

Re: 55hp powerhead 65 leg ???

Not a Chrysler expert but have played with motors since I was 6.
I'm surprised you are working without a manual.Over here you can sometimes find manuals at the library.
Found a 659H8B 1978,found a 559HK also 78.
WB29A Tillotson Carbs are used on the 65,WB27A or B are used on the 55.Sea level jets for WB29A .068 on the WB27A or B .066 jets are used.
Other sized jets are used also. Be sure yours are for the elevation you are at.
Best way to tell if the change is only the carbs is to compare parts/part numbers.It is about a 20% increase in power and only 250rpm difference.Not
an extreme change.Could be only the carbs.In my after market ser. manual
it appears the reeds are the same.
I wouldn't use just any silicon sealant but use what your wrecker or an outboard shop reccomends.There are silicon based gasket making compounds.
Sold at auto parts stores.I don't think the temps are extreme for your application.

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks heaps for the reply eurolarva & steelespike yes i have picked up some permatex ultrablue for the gaskets where the leg and spacerplate join onto the powerhead and also got industrial grade sealant for around the exhaust. eurolarva the two pics you posted of the lower units are exactly what i have and yes they are totaly different but the next section up which i refer to as the leg joins to an adapter plate that joins to the powerhead this is where it comes together, my power head looks exactly the same on the bottom ,the ports and the water outlet stud spacings drive shaft housing and seals exact so im wondering if the gear ratio on the 65 leg will be the same because the prop on the 65 seems smaller

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks for the jet info steelespike my 55 motor was running fine it was the bottom end that started all this stupidity to overcome the jumping out of foward gear i reversed the selector dog and it was going fine under full power so i thought i would get a second hand gearbox the wrecker said the 65 would fit so i bought it (sucker) then when it didnt he gave me the rest of the motor free so now i have both motors pulled down but it looks like it will all go together, so im going to reassemble the 65 leg with my powerhead and see how it goes first before i even try the different carbs on my motorso i can tell if the gear ratio makes any difference to the top end speed at wot which was 47kph on my gps thats kilometers ph not knots ph of course. but i was hoping to try changing the carbys later if it will give me more hp so my next question is eurolarva is to you (ol buddy ol chum)if you have a manual could you tell me iff the bore and stroke is the same on these two motors and is there more two it than just that

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

also folks the elevation is basically sea level so i guess the carbys on the 55must be tuned to that im not sure about the other ones. ive found out that it is to be sealed around the the exhaust(megaphone) and the top section of the leg. I am waiting on one seal for the bottom crank/drive shaft housing so i can put her back together if it doesnt work i can aways put my old leg back on

 

[steelespike]

Re: 55hp powerhead 65 leg ???

Bore and stroke are the same. If you open the carbs the jet size is visable with the jets installed.
You could check the gear ratio by rotating the driveshaft by hand and count the prop rotation.
Not sure how difficult but it seems you could put the best parts from the 2 gear cases into the 55 gearcase.
On some motors jumping out of gear fix can be a simple adjustment of the remote shift cable.

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks mate for the info on the bore / stroke ill check the carbs today oh and ill also count the ratio, good tip sometimes you overlook the most basic solutions!! the only real way to fix my 55 box is too replace the gear and selector because i tried full adjustment foward to get max pressure on the selector to the point it didnt even select reverse and it still jumped under load,even half throttle seemed fine at idle and just above but put the power on and bang what a nasty noise!! thats why i turned the selector and put the worn side to face reverse since i only use reverse at idle or just above and it worked fine both in reverse and foward under full load. but like eurolava said it will eventually wear unless i do something about those worn faces and when it does i dont want to be coming across the bar and end up on the rocks(like the pasha bulker) stuck on our beach here in Newcastle.I could get them machined or get some second hand parts that is how this project started out buying a second hand box and now look what Ive got myself into!!but its all good fun and the weather over here is to lousy to be on the water anyway, also the leg and box /prop off this 65 look a bit newer and flasher than the 55 so ill forge on and see how she goes Also the leg off this 65 is shorter buy about 1 inch so it will be good because the 55 had been raised up on the transom with a block of wood to get the cavatation plate level with the bottom of the boat so now it will sit snug on the transom and the cav?? plate rides just above the bottom Sorry about the long post i will try to get some pics today and post them tonight thanks for the interest guys mick

 

[Frank Acampora]

Re: 55hp powerhead 65 leg ???

If that is the engine I think it is, they made a 55, 60, and 65 with the same bore and stroke. Carbs and props were different for each horsepower. However, changing carbs alone may not give you the extra horsepower. sometimes they changed the bybass and exhaust timing. I am not sure on this engine. To check this, measure down from the top of the cylinder to the top of the ports. If the measurement is the same you may be able to get the extra horsepower with just a carb and prop change. If they are different, the difference will be about 1/16 inch or about 1.25 mm. --enough that you will easily be able to see it. I think all the engines had the same gear ratio. Be carefull! Do not use a prop that is too small. These were probably the best designed power heads Chrysler ever made. These engines develop gobs of horsepower at the low end rpm and with a too small prop, you will strip out gear teeth. Believe me--I have replaced them 3 times. They have weak gears in the lower unit.

By the way-- They made this engine --known as the big bore engine because the bore was 3.375 and the stroke was 2.80 inches. Just like the big 4 cylinder engines. However, The block was packed much better for way better volumetric efficiency. It was made for several years up to 1984 and was made with two different lower units. It also was made with Magna Power II which went bad regularly. You would be lucky to find a good replacement unit. Later models were made with Prestolite ignition.

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks Frank yes the 65 has magnapower 11 and the 55 has the prestolite flywheel also has magnapower wrote near the wiring key. does this motor charge a battery it only has starter cables running from the battery the rest of the wiring runs to the ignition switch then stops?? also not sure how to check the ports without removeing the heads, i checked the stroke with a screwdriver down the pots to top of piston at bottom of stroke and just a tiny difference i will try to get a better measure later (bit of a bush mechanic hey )

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

hi I just checked the ratio on the two boxes both seemed to be as best i could see to be the same 13 revolutions of driveshaft to 8 revs of prop on my calculater i think that works out to be 1.625 to 1 I also measured the props from centre of hub to outside of blade 120 mm on the 65 leg and 140 on 55 leg or prop? the measure from front to back of blade is 75 mm on 65hp and 55mm on 55hp but the hub siz is different so i guess i will just try it and see if it sound like it revs to hard then try a bigger prop or pitch??? just a query about stripping gears but wouldnt a bigger prop put more load on the motor and if the prop was to small it would just rev more?? anyway ill be using this boat for fishing more than sking so i probably wont need to put so much pressure on the gears anyway

 

[Frank Acampora]

Re: 55hp powerhead 65 leg ???

Contrary to what you might think, the smaller prop lets the engine rev up into its horsepower range quicker while the boat is going slow and the load on the gears increases. The higher pitch prop does not let the engine develop its horsepower quite so quickly so the boat is moving faster when maximum horsepower is developed and load on the gear teeth is not quite as much.
I'm talking about a full throttle hole shot. Takes about 5 seconds to strip the gears. I had an 11, 12, and 13 pitch prop. Fine with the 12 and 13. ran 4 weekends no problems. As soon as I installed the 11 pitch--there went the gears--first full throttle acceleration. Only a couple of hundred feet from the dock. I had this engine installed on a light fiberglass runabout 14 foot flat bottom and it went 45 MPH with either the 12 or 13--not too shabby!
Both engines should have an alternator under the flywheel. Not sure on MagII but Prestolite will have two green wires coming down to a rectifier mounted on the exhaust chest. red wire on rectifier will go to the loom and the terminal board to charge through the battery positive wire (same one used to power the start solenoid).
The only accurate way to check port timing is to remove the head. Even though this is a crossflow engine, the ports are huge and similar to the ports on the loop charged 3 cylinder Evinrudes.
You don't need to get the gear and clutch dogs machined. the faces will be rounded and show the wear quite distinctively. Simply chuck a small stone like a chainsaw sharpener or a carbide bit into a drill press and grind back to unworn metal. I frequently do it. You can also do it using a Dremel but you need to be a lot more careful.

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks Frank for the info on the props these two props look totally different to each other the one off the 55 is bigger 140 mm from centre to outside of blade but only {55mm from front to back of blade I think this is the pitch)?? and the one off the 65 is smaller 120 mm from centre to outside but is deeper 75mm from front to back the lagger prop off the 55 hes 12p stamped on it is this the pitch?? the other off the 65 has 493 13 stamped on it maybe a part number?? they are not interchangable because of the shaft setup so I will just be careful with the power when I get this thing back together nice to know it will charge my battery I am waiting on a seal for the crankshaft housing will be reasembling this week hopefully when you said you grind down the face of your selector and foward gear do you mean you shorten the selectog dog in length not the three faces individually ?? can you post a diagram please I am still trying to work out how to post a picture thanks Mick

 

[Frank Acampora]

Re: 55hp powerhead 65 leg ???

493 is the part number either from the manufacturer or Chrysler. 13 is the pitch. And it is correct--the 12 pitch has a larger diameter. I have a lot of trouble posting photos so try to understand me. The drive dogs are about 3/4 inch long and 1/4 inch high. you are going to leave them 1/4 inch high and shorten them from say 3/4 to about 5/8 inch. There will still be plenty of meat to take the load so you don't need to worry about them shearing off.
Think of it this way: There are only about 2-3 gear teeth engaged at any one time and even shortened, the drive dogs have much more thickness than that so there is no worry--you could probably take off half of the length and still not worry. The dogs on the gears are usually a little harder so they tend to wear less and you MAY not need to do them. However, if they show too much wear, they will need to be re-ground also.
I have never opened up an old style 60 gearcase so I do not know if the gears on them are weak or not.

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

thanks frank I know what you mean anyway I got my seal today and put it all back together tonight all went fine so tomorrow its off to the lake for the test run I have been looking at some pics of other motors and the later model 55hp and also the bigger models like the 140 have the same style of gearbox so mabye they are a bit stronger anyway I will let you know how she goes tomorrow cheers Mick

 

[aussiemik]

Re: 55hp powerhead 65 leg ???

hi to you all well today I took her to the lake and every thing went fine just a kilometre slower maybe the prop size not sure about revs no tacho but there was no oil /fuel running down the leg anymore, just like to thank everyone for their help with info certainly makes problem solving easier,cheers Mick