Piston Con rod orientation help please - Alfa Romeo Forum
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Old 23-10-12
reveds1969
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Piston Con rod orientation help please

Hi to all used to posting in the 916 but branched out to a bigger crowd hopefully.
I am in the process of stringing out a 2ltr twinspark engine rebuild i have cleaned everything maticulously
And now at the stage of reassembling the bottom end.
I made a point of stamping the caps to the rods however i did not mark which way the rods came out the pistons. Question is does it matter? Im using new shells for big ends and mains I have balanced the rods matchweighed gudgeon pins con rods pistons as i will be leaving out the balance shafts but thats another post to come.
Any ideas please
 
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Old 15-09-13
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As I recall the numbers face towards the exhaust side .... Caps are easy as the tabs go on the same side
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Old 22-09-13
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On many engines rods are not symetrical because pistons are offset to leave space for crank bearings. So yes it may be important and you should be able to see if you install them in a wrong way.
Balance shafts are a comfort feature, the crank is balance without them so you can remove them, especially because the TS crank is fully balanced. Race engine don't keep them.
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Old 22-09-13
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If it's for road use, don't leave the balance shafts out.

Do a search, those that have wouldn't recommend it. They are there for a reason, think about it, Alfa could have kept them out, saved on the cost of manufacturing them and fitting them, sold the car for the same price.

Unless you don't care about refinement, keep them in.
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Old 22-09-13
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Quote:
Originally Posted by Mitch916 View Post
If it's for road use, don't leave the balance shafts out.

Do a search, those that have wouldn't recommend it. They are there for a reason, think about it, Alfa could have kept them out, saved on the cost of manufacturing them and fitting them, sold the car for the same price.

Unless you don't care about refinement, keep them in.
The reason is the 2L is a long stroke engine which means more vibrations. On Lancia engines the crank was not fully balanced.
What are consequences you are talking about ? I know people having removed them on the 2L Alfa and they did not fill a lot of change neither reliability problems.
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Old 23-09-13
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Too much vibration (unsuprisingly) as I say, they are there for a reason.
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Old 24-09-13
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And another resurrected old thread ... Oct 2012!
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