scootz
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| posted on 15/10/11 at 08:47 AM |
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Lightening & Knife-Edging Crankshafts
Following on from my knackered 350Z engine thread... Linky
The definite junk items are two valves, all pistons, 1 rod and the engine block.
The crank has some gouges on the offending pistons counter-weight portion. Assuming it passes crack testing inspection, then I'd probably see
if I can tidy it by lightening and knife-edging it.
What are the typical parameters that define how much 'meat' you can take from a crankshaft?
It's Evolution Baby!
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snapper
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| posted on 15/10/11 at 02:37 PM |
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You don't want to take to much weight off unless your rods and pistons are much lighter, it is a counter weight.
You can knife edge but leave the areas near the main body of the crank alone.
The only reason to knife edge is for very high rpm, this will lighted the crank anyway.
Balancing the crank is usually done by drilling into the web, difficult if you knife edge it.
I balanced, polished and fitted a crank scraper.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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MakeEverything
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| posted on 15/10/11 at 03:37 PM |
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There is no proven results that show the benefits of knife-edging a crankshaft, so i wouldnt bother - particularly as the engine you have needs money
in other areas. The whole thing sounds as though it needs crack testing, and is one of the liners cracked in one of your photos as well?
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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scootz
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| posted on 15/10/11 at 04:49 PM |
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Yup... block and liners are knackered!
I appreciate that the performance benefits are questionable, that's why I'd be looking to do it from the perspective of getting rid of the
scored area of the crank and salvaging it.
Crack-testing, lightening and / knife-edging is cheaper than a replacement crank.
Bear in mind also that I bought the lump to strip-down completely and fiddle with, so the more virginal fettling the better! 
It's Evolution Baby!
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Rod Ends
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 posted on 15/10/11 at 10:08 PM |
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Anatomy Of A Super Crank
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spiderman
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| posted on 16/10/11 at 01:49 AM |
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If the block and pistons are knackered plus two of the valves and the crank has gouges in it, what is worth saving? Would it not be better to spend
the money on a decent motor?
Spider
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scootz
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| posted on 16/10/11 at 07:10 AM |
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... because I want to build an engine!
It's Evolution Baby!
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franky
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| posted on 16/10/11 at 08:17 AM |
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quote:
Originally posted by scootz
... because I want to build an engine!
What you thinking of putting it in?
Without getting romantic, I saw this and thought of you
Nissan 350Z Head Gasket Engine Set 3.5cc New Genuine 10101CD325 | eBay
Should save you a few quid.
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scootz
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| posted on 16/10/11 at 10:10 AM |
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Cheers Franky!
Now in my "Watch List"!
Not sure what I want to achieve with it really... I just want to do things with the internals that I've never done before!
It's Evolution Baby!
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scootz
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| posted on 23/10/11 at 08:43 PM |
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quote:
Originally posted by franky
Without getting romantic, I saw this and thought of you
Nissan 350Z Head Gasket Engine Set 3.5cc New Genuine 10101CD325 | eBay
Should save you a few quid.
Thanks again Mister!
Mine for £28 delivered!
It's Evolution Baby!
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