1989 Evinrude 120 HP looper - Re-manufactured Power Head and Carb jets conundrum

[REDDOG185]

I have a 1989 Evinrude 120 hp that I bought new. I stupidly ruined it about 10 years ago by seizing cylinder 3 due to a lean condition. It has been in the garage since. I want to fix it, so I am looking to buy a remanufactured power head. The company at which I am looking has their installation instructions on-line. The first item says to install .0002 larger jets in the carb.

I sent the company an email stating that I was thinking about buying the power head, but had a couple of question. First, I asked if this was all the jets or just the high speed jet. Second, I stated that surely this is a typo, that the decimal point is surely in the wrong place, that there is probably .0002 tolerance in the manufacture of the original jets and that surely they mean to install .002 larger jets.

The support person responded that he was not a tech, that the company now had no techs on staff now (I don't know if this is because of the virus or just because....), and that I should ask a forum such as this.

So what do you think? As for the first question, I could be wrong, but I think the idle jet and intermediate jet are merely air jets and making them larger would make the mixture leaner, if anything. So, I think the high speed jet is the jet of concern. As for the second question, I think surely it should be .002 larger. Any thoughts?

 

[racerone]

Correct that should read 0.002" on the jet change !----If you did the math on the area with a 0.0002" change it would confirm that.------And right the factory jet could be in fact bigger than their suggested 0.0002" change.

 

[oldboat1]

What was the issue 10 yrs ago -- VRO failure, maybe? Is it currently seized up?

 

[REDDOG185]

Thanks for your input! Any thoughts on the first question - you think the larger jet recommendation would be for just the high speed jet or all three jets - high speed, intermediate and idle? I am not sure, but I suspect that the idle and intermediate jets or just air jets rather than fuel jets.

 

[REDDOG185]

In response to oldboat1, I took it out for the first time of the season in a rush. It was really cutting out bad and missing and I thought if I run it wide open a while it would burn out the kunk and start running right. I was really wrong. The VRO was working fine, but the clogged carb destroyed that cylinder.

 

[oldboat1]

Think a lean condition serious enough to seize up the piston would be high rpm -- h.s. jet, poss. h.s. and intermediate.

But think the engine would stall out before damage if jet size was the issue.

[Edit didn't see your reply post before posting myself, but inclined to think a clogged jet would stall engine as well, prior to damage.]

 

[REDDOG185]

In further response to oldboat1, I am just trying to figure out some recommendations from a company's re-manufactured power head installation instructions when the company that provided the instructions couldn't answer my question. I knew my problem was caused by the carbs so I first bought carb overhaul kits and while I had the carbs apart wanted to address the jetting question, but the company couldn't help. The carb to the burned cylinder had clogged orifices in the emulsion tube. That is all I saw wrong with it. But that cylinder got so hot and dry that it seized that cylinder, resulted in the connecting rod bolts breaking then the crank hit the protruding connecting rod after turning 180 degrees and even cracked the case in that area internally. It took me ten years to decide that I was just going to have to cur off the flywheel if I was ever going to get it off. The engine made a loud pop and stopped immediately. It sheared the flywheel key and essentially welded the flywheel to the shaft. I determined the extent of the internal damage when I finally got the flywheel off. An engine shop told me to try a re-manufactured power head as that one was not salvageable.

 

[Faztbullet]

Install the next size up high speed jet to all carbs(which is .002 larger) and spot on the timing. Do the proper break-in of powerhead..

 

[oldboat1]

Ouch!! .063 would be the standard h.s. jet, so appears the rebuilder is calling for .065 (1/4-20 thread size.)

 

[REDDOG185]

Faztbullet, the company instructions also said to retard the timing 2 degrees. What are your thoughts on that?

 

[REDDOG185]

That is correct oldboat 1. I have the part number. I just hope I can find the jet.

 

[REDDOG185]

I just found the .065 D jet on-line and am going to order four of them. Thanks to everyone for your help. Obviously this is not a fast moving project, but I will post an update as things move forward. Thanks again.

 

[Faztbullet]

Faztbullet, the company instructions also said to retard the timing 2 degrees. What are your thoughts on that? ​

Who is the reman company?? Yes retard during break-in the set back to OEM spec. If you got some extra coins find a set of 140 carbs and slap on it

 

[REDDOG185]

Faztbullet, the company from which I am considering purchasing is Crowley Marine on-line out of Denver. Their web page says it is a Crowley Marine Brand product. I don't know who really does them for them. Thanks for answering the timing question.

 

[REDDOG185]

Another thing Faztbullet, I have compared the parts diagrams for the 1989 120 and 140 loopers. The only different part number for the carburetors on each engine is the the intermediate orifice. It is slightly larger. Why would you change out the carbs?

 

[oldboat1]

fyi: iBoats sources through Crowley (i.e., iBoats help desk can run interference if you need it, and you can of course order Crowley-sourced products through iBoats.)

 

[REDDOG185]

That is good to know oldboat 1. Thanks.

 

[Faztbullet]

The only different part number for the carburetors on each engine is the the intermediate orifice. It is slightly larger. Why would you change out the carbs? ​

You change out the carb bodies as venturi is larger....look at parts again and you will see 2 different part numbers for carb bodies. That powerhead is a OBR reman that 90% of online dealers carry..

 

[REDDOG185]

Faztbullet, what is OBR?

Anyone, I have another problem/question.

I got the larger main jets I ordered Friday, so started the carb rebuild today in anticipation of getting that done and ordering the reman power head. Then I ran into another issue. I suspect that the carb rebuild kit (which is OEM) is made for more than one carb. In fact, I know it came with a gasket that does not go to my carbs, but it also came with a nylon washer for the needle valve seat. My carbs do not have a washer on the needle valve seat, Should I use the nylon washer or not? Any suggestions?

 

[Faztbullet]

what is OBR? ​

Out Board Recycle/Red Rhino...Semmes ,Al

Should I use the nylon washer or not? Any suggestions? ​

Do not use washer..OMC/BRP when to a universal kits years ago and since 90% of Johnrude carbs use same needle/seat the washer is left in package. Also you will have several mounting o-ring and side gaskets so user correct ones