boxer engine

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sbdtasos

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and we have the first failure .the bearing of the conecting rod is broken
i change it and try to start the engine again and the bearing again broke.i dont know the reason.now i have install brass bushes and i will see the results

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michael-au

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Hope you get it sorted out, will be good to see it running
 

ninefinger

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My initial gut feel is that the ball bearing is undersized for the load. Looking at full size applications - 2 stroke boat motors for one - I've seen needle roller bearings on the connecting rod big end. Even in modern car engines they are using babbit bearings as the load is quite high at this location in the engine. I think you will find your brass bushes will serve well in this application.
Looking good - excited to see it run.

Good luck.
Mike
 

michelko

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I agree with Mike. The bearing balls Look realy tiny.
Michael
 

Mechanicboy

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Even in modern car engines they are using babbit bearings as the load is quite high at this location in the engine.

Mike
Mike, i am car mechanic and can tell you the babbit bearings is not longer in use in the modern car engines. Also we are using aluminium bearing alloys. The aluminium alloy bearing have wear resistance, high load-carrying capacity, fatigue strength, thermal conductivity, and excellent corrosion resistance, and low cost. The aluminium alloy bearing last long life up to 300 000 km to 400 000 km before the bearing is worned. The world's highest mileage car, a 1966 Volvo P1800, has traveled more than 4,828,032 km (3,000,000 mi) on its original B18 engine.
 

Mechanicboy

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Use bronze instead brass, it will last much better. Brass is not solid as bronze. Make lubricating hole under the connecting rod where there is not pressure zone to be sure the bearing is well lubricated since you do not have oil canal inside the crankshaft to lubricate the connecting rod bearings and crank shaft bearings.
 

sbdtasos

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in all my engines i use bearings 6x10x3 on the rods with no faulier
on this engine i use bearing 8x12x3,5 and i have this problems
now i think that will be ok with the brass bushes
now i trying to start the engine but i have some issues
as you will se on video the engine start but stop after 2-3 seconds
when i close the carb with my finger the engine start but only for 2 - 3 seconds after is not starting
i check the timming and i want everybodys opinion for that
my camshaft timing at 40 before tdc and close 30 after bdc for the intake
and for the exhaust 30 before bdc and 40 after tdc
i check my camshaft and i want your opinions for my timminig if is ok or not
cylinder 1 in -30 btdc +40 atdc
ex -30 bbdc+30 abdc
cylinder 2 in -25 btdc+45 atdc
ex -35 bbdc +45 abdc
cylinder 3 in -40 btdc+35 atdc
ex -30 bbdc+35 abdc
cylinder 4 in -40 btdc+30 atdc
ex -30 bbdc+40 abdc
do you thing that this timinig is a problem?


[ame]https://www.youtube.com/watch?v=js5OguG-bLs&feature=youtu.be[/ame]
 

ninefinger

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What is your ignition timing like? And what do you have for a flywheel? Sounds like it might be either to aggressive ignition and/or too little flywheel to keep it going.
 

ninefinger

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Mike, i am car mechanic and can tell you the babbit bearings is not longer in use in the modern car engines. Also we are using aluminium bearing alloys. The aluminium alloy bearing have wear resistance, high load-carrying capacity, fatigue strength, thermal conductivity, and excellent corrosion resistance, and low cost.
I use babbit bearings as a general description for hydrodynamic bearings of that type, not meant to imply the actual construction of the bearing itself.
Basically an oil film bearing has a much higher load capacity than a ball bearing of the same outer / inner diameter and width.

Mike
 

sbdtasos

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What is your ignition timing like? And what do you have for a flywheel? Sounds like it might be either to aggressive ignition and/or too little flywheel to keep it going.
90% ignition have problem
yes i know that engine looks like that have to much ignition timing
but is only 25 degrees btdc
i am waiting a new ignition and i will try again to start the engine
 

pp2076

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and we have the first failure .the bearing of the conecting rod is broken
i change it and try to start the engine again and the bearing again broke.i dont know the reason.now i have install brass bushes and i will see the results
Fake Chinese bearings perhaps?
 
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