1983 J150STLCTE Compression/Rebuild

[sledmonster]

So I posted about this almost a year ago. But its finally time. Rebuild on the way, questions though. The reason for the rebuild is 70-75 PSI in all 6 cylinders. How is it possible to run a motor to this point? When I purchased it for 300.00$ it didnt run (right), no kidding. I just hope this is the problem. It had/has issues similiar to lack of fuel.

Im thinking of doing just pistons, rings, wrist pins/bearing an bore it, but not touch the crank? Any opinions.

Any lines on full pre-packaged rebuild kits?

 

[sledmonster]

Re: 1983 J150STLCTE Compression/Rebuild

Any ideas?

 

[Walker]

Re: 1983 J150STLCTE Compression/Rebuild

Why do it half way??

 

[emdsapmgr]

Re: 1983 J150STLCTE Compression/Rebuild

In stock form, your engine should be crank rated at around 165 hp. If the journals on the crank are not pitted, use it as is. When completed, the compression should increase dramatically-in the 95-105 range. You can find better heads for your engine, which can get you towards 120. It already has the big carbs, so you are good to go with them, but would require rejetting if you put on tighter heads. I would add the intake filler blocks, 322722. (they are NLA, but you can find them around and will add HP.) As set of composite reeds is also a nice addition. Your engine originally came with one unlimited pack and one rev limit pack. Those are no longer avail, and if replaced through the years, the replacements are rev limited to 5800 rpm. I would look for a set of the old (NLA) 582138 packs to really let the engine get moving. Your engine has the stiff engine mounts as well as the hood vents-nice features.

 

[Dhadley]

Re: 1983 J150STLCTE Compression/Rebuild

Since the compression is that even on all 6 have you tried a good decarb job?

 

[sledmonster]

Re: 1983 J150STLCTE Compression/Rebuild

Thanks all for the replies.

I had done 3 seafoams on the engine last fall with no improvements. None of the pistons are scored/scratched (as visible from the exaust cover) and i cant remember if i checked the rings if they were still stuck. The engine was used a a tournament bass engine, it has a custom nose piece/leading edge infront of the prop with a lot of time out into it so I think it just has lots of hours.

 

[sledmonster]

Re: 1983 J150STLCTE Compression/Rebuild

Just for some more info this motor is on a 1977 Sidewinder it weighs in at 988lbs with 8 gallons of fuel. It ran 58mph with it trimmed out on choppy day. It was really hard to get it to power up i had to play with the choke/primer module to get it to wind out.? As if it werent getting enough fuel? I wonder if reeds failing would give bad comp numbers?

 

[Dhadley]

Re: 1983 J150STLCTE Compression/Rebuild

More likely some partially plugged carbs. Be careful.

 

[emdsapmgr]

Re: 1983 J150STLCTE Compression/Rebuild

Not sure why you are still trying to get the engine to run well, with compression as low as it is. Continued running of a tired engine bears some risk. You could throw a ring and wind up with other repair issues.

 

[sledmonster]

Re: 1983 J150STLCTE Compression/Rebuild

I havent run the engine since last year. All testing was done just after I mounted it. I have simply been postponing the innevitable. Thanks for the tips I will be ordering a complete rebuild for her. 1400.00$ CDN. out of BC, Im up in the Yukon the ice just came off our lakes 2 weeks ago.

Would the low compression readings, and possibly bad crank seals cause the hard running? Either way I guess I'll have to put a 1969 115 Johnny back on her. She ran 46Mph with a 17 pitch no name SS, with the cav plate 1.5" above the keel.

Thanks to all.

 

[R.Johnson]

Re: 1983 J150STLCTE Compression/Rebuild

Compression testers can vary all over the board,I have Snap-on, Mac, generic, with Marchall gage. They read all over the board. I use one for a quick check. Any question, I use a leak-down tester. That can fool you too. Pull the head has never failed.