50hp early Force parts fit 55hp1973 Chrysler?

[tater76]

Hi guys, so I have a 73 55hp Chrysler and I came across a a 50hp Force for sale for $100 bucks. It has a broken crank supposedly. From the pics in the add it all looks the same under the hood as my 73? It didnt have a year or model, but it did have the early looking force sticker on the cowel. My question is should I buy it just for the lower end and other parts? Would they fit? I know its alot to ask without a model or year number, but it really looks identical to what I am running.

 

[Frank Acampora]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

Without a photo, it is difficult to tell. HOWEVER: Early Force engine were very similar to Chryslers. In fact, I have just recently mounted an 89 Force powerhead on a 67 Chrysler. SO, if it looks the same, it probably is and most parts will fit. You could even swap your crank into it if you wanted to do the work. However, with a broken crank, it is possible that the inside is messed up. Try to do a little better on price. In the end though, if you really want it, yeah, the lower unit alone is worth it, especially if you need it.

 

[tater76]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

Thanks Frank, so I ended up buying the motor for $100 bucks. It is a 1985 model 50hp Force. The guy had the head off, and the lower piston missing when I arrived. The motor was spotless, everything was there except the lower piston. He could not find it in his shop, and I believe him, but the cylinder walls were in amazing shape so? Here is my dilemma, my 73 55hp runs great but is points ignition. The 50 Force is newer, better looking, and has electronic ignition. What would you do? Oh, and the 50 crank is not broken, the rod on the piston broke, think its worth it to buy a new piston and rod and try to get it running as is?

 

[Frank Acampora]

Re: 50hp early Force parts fit 55hp1973 Chrysler?



Here's a points ignition Chrysler 50 that is doing 45 MPH. No problem with that baby.

Buying a new rod and piston would not be cost effective. The rod is well over 200 bucks and pistons run from 70 up to about 125. So, you could have 400-600 invested in an engine that on a good day would sell for 500

Nothing is wrong with points ignition. They ran very well for years. The electronic is a little less maintenance and perhaps a tiny skeench more power is delivered by the engine, but not enough to warrant stripping your 55.

The rods are the same from any Chrysler or Force from 20 up to 150 Horsepower with the exception of the late Force 90 and 75 so if you find a junker, you could salvage a rod from that.

If the piston is 3.187, you need to buy a new one or again, find a 50 or 55 to salvage one from. If it is the big bore 50 with 3.375 bore, then the piston would come out of a 120 or again buy a new one.

I'm not sure how the electronic ignition on the 50 is but I THINK the crank is different since it does not have a slip-on cam. SO: you would possibly need to change the crank if you wanted to change the ignition--too much work for too little gain.

However if you see that the crank nose is the same then the whole ignition might just swap with just a couple of mounting holed drilled on the top of the block--this is for you to see and decide.

 

[tater76]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

Thanks again Frank, well, I pulled all of the ignition parts off of the 50 last night. It revealed some nice sized holes in the case from the rod that broke, so nevermind on the rebuild. With this in mind I thought of swapping over the 50 ignition to my 55 while it was apart. I set the two motors side by side took them apart for the swap. Removed the plate that holds the points and condensors on both motors, and to my horror the 55 upper ball bearing had about half the bearings it should, and there were broken ones inside the cage. My question is can I replace this bearing without separating the case?

 

[Frank Acampora]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

View attachment 87359

No! You must remove the crank to pull the top bearing and additionally you must have a heavy duty press with the special bearing puller. So, for the time being, if the crank and bearing on the 50 is good then swap it in. It is the same stroke as the 55.

There you go-- bearing is a Ford rear end bearing at about 30 bucks in the auto store, plus the cost for a machine shop to pull the old bearing---you have already save half the price you paid for the 50.

Top bearing only has about 8 balls, but if some are damaged, you have no choice but to repair them. While you have the engine apart, clean the inside well to remove any metal pieces. And if you get enthusiastic, port the engine with a Dremel and carbide bit--it will perk it up a bit. Look at the two photos showing a ported two cylinder.

 

[tater76]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

Ok Frank, so the 50hp crank has a spun bearing and is chewed up beyond repair. Otherwise I would do what you said and swap cranks. Now, so I will have the good 55 torn down to nothing so should I do rings and a hone job while I am there? or I could just have the dang thing bored out while its apart, and spend some dough on bigger pistons? I really don't want to spend any more than necessary at this point, so I am thinking a new gasket kit for the block and replace the bearing then call it good.

 

[tater76]

Re: 50hp early Force parts fit 55hp1973 Chrysler?

Hi Frank, I am at the point of no return now with my 55. The crank is out and I have a new bearing and gasket kit on the way. Now my question is that during the teardown I noticed the upper cylinder has some light scoring. This was from the carb being improperly adjusted when I first took ownership. The piston was being melted, so there is some minimal damage. The motor ran very well after a carb rebuild, and the upper cylinder retained 120psi. Now, I have it all apart for cleaning and thought maybe I should hone the upper cylinder to take the scratches out. Then I could use the good 50 piston to replace the melted one? I plan on completely tearing down the powerhead, cleaning, degreasing, new seals throughout, porting as you suggested,etc.. so I may as well do it right at this point. Any more suggestions?