1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

[JohnnCash]

Looking at rebuilding the old 1986 120 looper on the back of my Aquasport 170 Osprey. The other option would be repowering with a rebuilt 90 Johnson. The 90 hp is a '89 and would be right at $1,800. I have a few questions that I'm hoping the experts here can help me out with...

- What is the real difference between the 1986 Big Block 120 and 140 loopers? I have read that the jets in the carbs are the only real variation between the two, is this true and if so can you "simply" convert the motor while rebuilding the carbs?

- The piece at the top of the steering shaft is rusted out & barely holding on and needs to be replace. Where can I find a replacement steering shaft that is not major $$$s? The replacements online are almost $800 which would make the repower the way to go.

- Is rebuilding the way to go? I would like to know what is what on the back of my boat; however, I don't want to get through and have spent way more rebuilding than repowering.

I really appreciate any and all insight here... I'm sure there will be more questions to come...

Thanks!

 

[multimech]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

Is this an engine that has been in salt water it's entire life? Sounds like it if the steering arm is rusted to ****. That would indicate to me that the block is in just as bad condition, not worth the rebuild. Sure go with the "rebuilt" 90 HP as long as you do a compression, spark check. Check the trim and tilt and generally look over the engine for corrosion issues. I don't know about jets being the only difference. I do know that exhaust tuning is also a difference in differing HP engines.

 

[boobie]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

The '86 looper was "dog". At the marina I worked at we wouldn't even sell one but had to work on plenty of them. Go with the 90 hp and don't stick any money in that looper.

 

[Faztbullet]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

The 86 120/140 was a small bore bridged port engine, the difference between the 120/140 was carbs. These older carbs never idled well but ran ok above 3500 if you got there...go with the 90hp or a later model engine.

 

[boobie]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

You said the magic words Fazt. " above 3500 if you got there ".

 

[JohnnCash]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

Wow... not the responses I was expecting at all... I was thinking I was going to hear about how great the motor was and not to let it go... I really do appreciate the wisdom.

It did spend almost all if its life in the salt. The heads actually look good and when we pulled them off the cylinders looked good as well.

 

[Kinchafoonee Bob]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

looks like its time to part it out and apply that money to the 90

 

[JohnnCash]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

nice avatar...

 

[sawdude]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

Wow, not the response I would have expected either, I always read about what a bulletproof tank the loopers are. I Have a 92 140 on the back of a 20ft seaswirl. Heavy boat, but quick to plane, WOT 5500 rpm/ 42mph, cruise @4200/31 mph. I like this boat, and will repower with something new one day, but this has been the most trouble free motor I have ever had. The one thing ill agree with, it has always had a "not quite smooth" idle, but if its not running well up from there go thru the carbs, easy and cheap cheap cheap. I see quite a few running around the San Juans here still, relatively cheap to run...for what its worth

 

[Dhadley]

Re: 1986 120 Johnson V4 Looper Rebuild - Help/Advice needed

We've always had good luck with the V4 loopers, even the early ones. There were some things to do to help the idle quality but if you rebuild one you can use the later model light rods, that will also help. That motor can be bored to the "big bore" spec and you can use the lighter 93 & up V6 pistons. The 86 also had a different timing spec. We never really cared for the V6 style gearcase (wierd ratio) found on some V4s though.