Engine swap (repower)

[ddbyrd3]

Re: Engine swap (repower)

I will have to do this when I get home tonight..<br /><br />You know that work thing is getting in the way of my being able to work on my toys....<br /><br />Such is life...

 

[Dhadley]

Re: Engine swap (repower)

You can also run it and check it the same way. Just unhook the linkage so the carbs dont open.

 

[Dhadley]

Re: Engine swap (repower)

If youre in Calif -- it must be the middle of the night for you now! I hope youre not awake worring about your motor!

 

[ddbyrd3]

Re: Engine swap (repower)

No, actually getting ready for work @ 5:15 am..<br /><br />Had to to make time to chect the important stuff though....

 

[ddbyrd3]

Re: Engine swap (repower)

OK.. had an oppertunity to verify the timing.. I did it a little differant than posted here. I had the engine running, disconnected the timing advance arm, and advanced the arm to the stop without advancing the throttle.<br /><br />I found the timing to be at 21.5*. I loosened the stop nut, and screwed the stop out approximatly 5 turns untin the timing was at 24*.<br /><br />Does that sound right...<br /><br />I wont be able to do a compression test until I get back from my trip..<br /><br />What do you think, could 2* have a drastic effect on overall performance?

 

[ddbyrd3]

Re: Engine swap (repower)

Hey cool, I graduated to a "Seaman Apprentice" By the time I get this motor figured out I will be an "Admiral" and DHadley will be "Commander and Chief".

 

[Basscat 1]

Re: Engine swap (repower)

21.5* to 24* seems like a big stretch to me. You may be onto something here.<br />Here is a better way of checking your timing which is what Dh is talking about.<br /> web page

 

[ddbyrd3]

Re: Engine swap (repower)

Thanks, I read on another post that specified doing it the way I described earlier. Also DH said I could do it while the motor is running. Is the way I did it OK, or should I pull the plugs, ground them and recheck it again the way the post you gave me suggested?<br /><br />21.5* to 24* is a big difference performance wise??

 

[Dhadley]

Re: Engine swap (repower)

Something still isnt right. 5 turns should have moved the timing about 5*. I'd sure check it under a load before running it very long.<br /><br />If it was at 20-21 static then it would have been about 24-25 at wot. Which is about where folks like to leave them after a rebuild for break-in. It will make some difference but not 1000 rpm.

 

[ddbyrd3]

Re: Engine swap (repower)

In order to check it under load, I need to be at WOT, 5000 rpm on the water correct?<br /><br />I may be mistaken on the # of turns, I did not actually count the number of rotations I made with the screwdriver..

 

[Dhadley]

Re: Engine swap (repower)

We do it with the boat still on the trailer and backed down the ramp if its hard to do while bouncing along at speed. As long as the motor gets to about 5000 or so.

 

[ddbyrd3]

Re: Engine swap (repower)

So you leave the boat on the trailer, back it into the water and run the motor (with prop engaged) to 5000RPM <br /><br />I assume if I cant get the motor to pull 5k, 48k or so will be OK?? <br /><br />I static timed the motor with a hush muffler on my prop does that make a difference when setting static timing. It creates a certain amount of back pressure..

 

[Dhadley]

Re: Engine swap (repower)

I think youll be real close. Yes, 4800 will be cool.

 

[Dhadley]

Re: Engine swap (repower)

Quick thought -- while its backed down the ramp, check each plug wire at wot. (You dont have to time each cylinder, just see if the light flashes) Just to make sure we're not losing a cylinder after mid range. I suspect we're not but while youre there....

 

[xikxak]

Re: Engine swap (repower)

Originally posted by ddbyrd3:<br /> So you leave the boat on the trailer, back it into the water and run the motor (with prop engaged) to 5000RPM <br /> or so will be OK?? <br /><br /> 5000 rpm,on trailer with PROP ENGAGED.is that right. sounds scary to me.not to question anyone,but as tthis point overlooked. dave

 

[ddbyrd3]

Re: Engine swap (repower)

Question.. I noticed in the part finder that there is a standard head gasket, and a low compression head gasket.. My Engine builder said there was no such thing as a "low compression head gasket" whats the deal is this guy just stroken me??<br /><br />Can anyone comment on the difference as far as thickness, etc. I will be doing a compression check tonight and I will post numbers tomorrow.. I am EXTERMELY curious now..

 

[Dhadley]

Re: Engine swap (repower)

My Engine builder said there was no such thing as a "low compression head gasket"

Humm....he rebuilds E/J motors but doesnt know about the low compression gaskets? A bit scarey...<br /><br />The "low compression" or thick gaskets came out in the 70's when they got the lead out (pun intended) of the fuel. The engineers all predicted that existing 2 strokes would fail immidately on no-lead fuel. They predicted a lot of stuff that didnt happen.

 

[ddbyrd3]

Re: Engine swap (repower)

I specifically asked, "did you install a low compression head gasket" he told me they dont make LCHG's. <br /><br />Since I have been chasing my power loss problem I figured timing, and low compression head gaskets.<br /><br />The only way to verify they are NOT low compression is to replace them right??

 

[ddbyrd3]

Re: Engine swap (repower)

My model number for this motor is: J140TXCIM<br />s/n# J5511112. <br /><br />Does anyone have the breakdown of the model number, shaft length, etc?

 

[Dhadley]

Re: Engine swap (repower)

That indicates its a 1981 and is a 25" motor.