Re: 85 HP Chrysler
Well, Noah--Where are you going to get a running 85 HP engine for 300 bucks?
I am building a slightly newer one now for fun and since I am not desperate to sell it I would ask 500-700 bucks.
As a junker I would pay anywhere from 50 to 150 bucks depending upon what I thought I could salvage. You might try to chew him down 50 bucks to compensate for your gas. And certainly, if it does not have a prop don't go higher than 250.
Remember: while he says it is a running engine, it is an unknown to you. You may end up replacing seals in the lower unit. If he has not done so, you WILL replace the water pump impeller fuel pump diaphragm, and change gear oil. While not a lot of money, it still is an out of pocket expense.
BUT: If it is as clean as you say and if compression is equal or close on all cylinders and at least 100 PSI, and has all parts, then yes, it is worth the 300. New compression was about 145 PSI.
You can re-use the controls and electrical cable from your 55 if replacing it is what you have in mind. Of course, try to get any control box and cables (if any) he has with the engine. If your boat is rated for the 85, you won't regret it. It is a quantum leap above the 55 in every way. I actually prefer the 3 cylinder engines to the four cylinder engines. BUT: On a larger boat, as the saying goes, "You can't beat cubic inches"
Being a 1970 engine, It will most likely have a Motorola CD ignition with the distributor having points to signal the CD box. In the future, you could easily upgrade to an electronic distributor which is more precise than points and will not change setting. It will be a 2 piece lower unit with (I think) an 18 spline prop shaft and a pin located prop. I never liked that arrangement, but I have run my 1976 90 HP for years with it without any problems. You can not buy these props new. You must find someone (like me) who has some sitting around. Although it appears to have a shear pin, the splines on the prop shaft drive the prop and the 5/16 pin takes thrust loads while locating the prop on the shaft.
Be absolutely certain that the seller gives you the tailcone. It locates the prop pin and without it , even with the prop, you can not run the engine. AND-- the tailcones are difficult to find and expensive. Oh, ok: You can use a 5/16 bolt and nut without the cone but it looks sloppy; there is not enough room between the pin and the hub for the bolt head so the bolt must be longer than the hub is wide.
If it has power trim/tilt, so much the better bargain. If not, later almost any trim/tilt unit at least up to 1994 will fit. When you do get trim, you will never want to live without it again.
While old, these engines are dirt common and most parts can be found rather easily. You can swap in many parts from later Force engines. Ignition systems from later engines can be retrofit with a bit of work and an added part or two, but there is no real reason to do so.
Lower units up from 75 to 140HP to about 1978 are swappable. Even though they physically look different, the mounting pattern, water pump, and drive shaft are the same. As long as it is a 2 piece lower unit it will fit.
The midleg is 1 inch longer than the newer one piece lower Chrysler and Force engines so start by mounting the engine clamps 1 inch above the transom. This should put the ventilation plate even with the bottom. Drill the BOTTOM hole in the clamp ( if there are two) so if you need to lower it an inch later, you won't need to drill two more holes. Most engines had two holes in the clamps; earlier engines only had one hole--not sure about yours.
Good luck!
