Sea Rayder 120 engine swap

[steelauzzy]

hey i have a 95 searay sea rayder with a merc 120 that was just built up from scratch. the mechanic must have not properly fasened the piston rod on because it busted through the block. So now i either need to repair the block or get a new one. does anyone know if there is a different engine that i can easily swap this for? does force or mercruiser make a similar engine that i can switch with? Thankyou

 

[steelauzzy]

Re: Sea Rayder 120 engine swap

Hey for anyone who reads this post in the future or is interested in switching mercury force power heads at least the 120Hp it IS totally possible. And very easy as well. There are a few changes that have to be done but if you have the core from the motor you are looking to replace you wont have a problem.
Parts that need to be changed include exhaust manifold and exhaust block-off plate need to be switched. The force uses the lower unit for the exhaust were the merc inboard uses a manifold and pipe to direct the exhaust into the jet chamber housing.
Also obviously the wiring differs from the outboard to the inboard. The modules are very similar and anyone with a wiring diagram could easily connect them up or even easier if you have the old electronics from the old motor just swap those over as everything will then be plug and play no splicing necessary. One thing that is different the starter solenoid bracked mount is missing on the force and different on the merc so you can either make a bracket or let it hang as i did.
The adapter plates are obviously different to go from the engine to the prop or to the jet. The gaskets are the same and they both bolt up and are perfectly interchangeable.
Fuel pump and water lines ect are all the same or easily switched over there are a few minor differences like oil injection and vac lines all can be ignored i recommend removing the oil pump if its still installed.
The only other thing that will not plug and play is the drive shaft splines and the crank will not mate up. The mercury uses a much beefier shaft and thicker splines the force is smaller diameter. The force will fit into the merc but its a terrible match and will almost definitely strip out very soon if not immediately. This problem is easily overcome if you can get your hands on a force drive shaft that mates with the force crank or vise versa for merc. You can remove the drive shaft and worm gear from the sport jet housing via the four bolts surrounding it and take a pry bar or chisel and hammer and break the seal lose and lift the flange seal bearing and shaft combo straight up out of the housing. This is a tonn faster than removing the entire jet housing and opening the back and pushing the gear and shaft up. Please note the shims between the flange and the seat do not lose any of these they are set to maintain the gear mesh gaps.
Once you have the shaft and bearing flange out you can hammer out the drive shaft from the flange numerous soft hits should do it take care not to damage the flange. Once the worm gear drive shaft is free you can take it to a machine shop and get them to cut off the splines drill a hole into the shaft insert a pin and do the same to the other crank spline shaft you aquired and get them to weld and balance them together. My shop did this for 50$ although it they didn't get it back to me for over a month. (welder got fired or something) Anyway The new polished shaft goes in just as it came out check the oil in the housing suck it out and replace it if needed and reinstall shims gaskets ext same as the came out. From there everything should bolt up superb!!
Good luck for any who try it! You can save a tonn!! i got my motor complete on ebay for 250$ with 200$ for freight i had the new engine in for just over 500$ another 500$ to fix the trailer and install new seats and trim some buffing and i took a 500$ boat and sold it for 3500$
Note Force 120 Carbs are also interchangeable. With the mercury only difference the mercury engine uses an electric auto choke and the force uses a manual butterfly choke i just removed the flap and installed it as is. The boat cranked up first try and ran beautiful was a blast on the lake!
And if anyone is still wondering the engines were 1995 ish. there are several years that also have interchangeable parts between force and mercury so good luck! and all the best!
Steelauzzy

 

[jdeboxtel]

Re: Sea Rayder 120 engine swap

IF you still have the carburetors from the 120, I'd like to buy them.