Lower unit swap 55 to 45 question

[FillupD]

Will a Chrysler 457HH swap with a 559HA motor. My 45hp has a broken cavitation plate and I want to see if a lower unit from a 55 hp parts motor will work Ok.

 

[Frank Acampora]

Re: Lower unit swap 55 to 45 question

I don't really know model numbers. If they are both long shaft or both short shaft engines, everything is the same, including gear ratios. That is, provided that the 55 is NOT a one piece lower unit, or two carb engine. Just bolt it on.

If the two engines are different shaft lengths, you need to swap the drive shafts and shift rods. If you remove the water pump, the drive shafts will just pull right out of the lower unit (they are splined to the pinion, but the pinion is located by a ball bearing.--So there is no fuss there). The shift rod simply unscrews and if you are careful not to disturb the shift or gears, it will screw right back into the other lower unit.

 

[FillupD]

Re: Lower unit swap 55 to 45 question

Thanks, I'll have to find out about the carbs and pieces. The 55 I am looking to buy for a parts motor has a broken crankshaft at the flywheel. That's probably pretty bad news huh?

 

[FillupD]

Re: Lower unit swap 55 to 45 question

Ok the parts motor has one carb and a longer shaft. I just change the shafts and not use the spacer right? It should bolt up short?
One side of the cavitation plate is broken on mine. It is worth 50 bucks to fix it isn't it? (It seems to run fine with it like that) Someone had tried to put a fin on it I think. One side has holes drilled in it and the other side is almost all gone.

 

[Frank Acampora]

Re: Lower unit swap 55 to 45 question

A broken crank at the flywheel is not necessarily the kiss of doom. If it is a single carbureted engine, crankshafts do come up occasionally on e bay. and if worst case, I have a 45 crank which while 1/16 less stroke will drop right in without any modifications. tear down and reassembly is relatively easy and you will still get close to 55 horses. Hope you are getting the engine cheap though--50 bucks or so sounds about right.

If it is a twin carb engine I also have a crank for that, BUT if it is 1978-1980 and is MAGNA-POWER II, stay away. It is nothing but problems and parts are difficult to find. If it is Prestolite ignition, it is OK but still look for a decent price--say less than 100 bucks since it still needs a crank. Note that parts are not swappable between twin carb and single carb engines.

Look for my private message to you

 

[Frank Acampora]

Re: Lower unit swap 55 to 45 question

Our posts crossed so ignore the PM part.

All you need to do is swap shafts and leave off the five inch extension. If you want to go to a long shaft on your 45, simply swap the whole lower with the extension and take out the five inch piece of water pump brass tubing. It should just pull right off and slip on over the 45 tube. ---Simple.

 

[FillupD]

Re: Lower unit swap 55 to 45 question

I'm going to go ahead and get the motor. I would be interested in putting a crank in it. I'll get it and take a look at it before I decide.
Thanks for the help. I'll let you know how it comes out or if I need some parts OK.