Force 150 vs. Force 125

[pastorbud]

So I bought a Force 125 and got a "bonus" Force 150 powerhead in the deal. I'd rather swap the powerheads, since my hull is rated for 150 hp, and the 125 powerhead has those warped, leaky plastic fuel drain covers you can't buy anymore. But two things:

1) I learned on this website that the Force 150's like to "eat" rings. Is that something very common? Is there a way to avoid that?

2) I'd like to check the compression on the 150 powerhead before I swap it. No point wasting time mounting a bad powerhead. Any advice on how to rig up a stand to support the powerhead while I run the compression check? Does it have to be vertical for that, or is there a safe way to turn it over with the motor laying horizontal? Right now, it's laying on it's side (ignition side up, starter side down) on a mechanic's creeper so I can move it around when I need to work in the garage. I can turn the flywheel freely, but I of course want it secure before I turn it over with the starter. No fuel connected (I'll squirt WD 40 and/or lithium grease in the spark plug holes for lube during testing), and all the CDI boxes are off, so I'm not worried about checking for spark or protecting the CDI's right now, just want to check compression before I go all crazy with this project.

Otherwise.... anybody know how to get those plastic fuel drain covers to stop leaking? I'll just leave the 125 hp powerhead on there if I can solve that problem.

 

[Frank Acampora]

There is no comparison between the 125 and the 150. The 150 with a dual exhaust will make the 125 look sick. It has equal length exhaust runners instead of dumping all exhaust into a common chest like the 125. The mounting studs are the same so the powerhead will bolt right onto the 125 leg. While it will bolt right on, if you have an older White Force, it will not fit into the upper or lower cowling.

You can check compression in any position as long as the flywheel is free to turn and not touching anything. Use jumper cables to crank the engine--negative to a good block ground and positive to the starter motor hot stud Do not use lithium grease; it is too heavy .Just use a little TWC-3 oil in the plug holes.

Just remember that the 150 block is quite a bit heavier than the 125. Unless you have one or two strong men or a lift, it will be very difficult to get onto the leg.

These engines like any Force with a semi-keystone top ring do tend to break the top ring. While not uncommon, this is by no means a certainty.

To prevent this you can try chamfering the exhaust ports but again, this is by no means a cure.

The only sure fire prevention is to replace the pistons with aftermarket pistons with regular rings like the Wiseco pistons.

AS I said, it is by no means a certainty that the engine will break rings. I bought my 150 with two bad pistons. I had two stock replacement pistons so I used them. IF the engine should ever break another ring I will use Wiseco pistons.

 

[pastorbud]

I've got a winch rigged up in the garage that I used to lift the 125 hp out of my truck. But I neglected to mention my 125 hp is a single exhaust, about 1989, I think. I'm uploading pics of the 150. The bolt patterns look right, but now I'm wondering about the exhaust.

BTW, those silver connector nuts on the bottom are just on there to protect the studs (a little). I left them on because I thought they might help if I need to rig up a way to stand it upright.

 

[Frank Acampora]

Nothing says you absolutely must use a dual exhaust lower unit. Your 150 will be fine with a single exhaust and no damage will be done. I have never compared a single exhaust and dual exhaust lower unit on the same engine. As I understand it, the dual exhaust unit was developed to increase power on later model Force engines (before the Mercury lower units were used). I do know that venting the lower unit with a number of 3/8 holes drilled above the anti-ventilation plate did increase speed on a Chrysler 140 that I modified.

 

[Frank Acampora]

No Title

You can see the vent hole on the lower unit in this photo.

 

[jerryjerry05]

What "leaky plastic things" you talking about?

 

[pastorbud]

Thanks for all the help. I hope to test compression after work today. The "leaky plastic things" are called (I think) "reed valve drain covers". My 125 hp has the plastic ones (other models have metal ones). They are right behind the ignition system on the side of the engine. The plastic ones eventually warp, and then the gaskets don't seal right. I've never found a solution.

 

[pastorbud]

I tried to do a compression test tonight, but my "bonus" 150 powerhead seems to have a bad starter. It tries to turn over, but can't spin the motor. Tried it with two different batteries and two sets of cables, so I'm pretty sure it's the starter. I'll have to wait until later in the week to rob one off the 125 hp motor.

 

[pastorbud]

Hey, I'm pretty stoked! Compression looks good, I think.

#1-- 150
#2-- 165
#3-- 165
#4-- 160
#5-- 170

Within tolerance, right?

 

[pnwboat]

Those compression numbers look very good.

 

[pastorbud]

I paid $60 for this thing.