ka crankshaft

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lexcrob
Posts: 559
Joined: Mon Sep 22, 2008 7:38 pm
Car: I get a different ride faster than I could update this.
Location: Clarksville, TN

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I guess ill start with the history on the engine. Bought 91 240sx few months ago engine blew 2nd day after a HEAVY drift beating. Made ticking sound from the time i bought it figured it was valvetrain/timing guides no biggie. It started knocking cruising home from beating. I shut it off right when i heard it knocking and pulled over. I decided to see if it would run after cooling off so it cranked right up and continued too knock but not very loud pulled off and it stalled. Called AAA got it to the house next day went out and tried to find out which cyl. was the culprit. Cranked right up poped hood and by time i went to pull plug wire it siezed! Again i repeated this and did'nt even get a wire off before watching the crank Sieze again. Needless to say i yanked her out and put it in the corner.


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lexcrob
Posts: 559
Joined: Mon Sep 22, 2008 7:38 pm
Car: I get a different ride faster than I could update this.
Location: Clarksville, TN

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Anyways ended up getting it for free last night and tore it down.

All journals look great but #4 it took a beating for shur. The wrist pin is binded up pretty tight too but can move by hand. I guess something happened with the timing since a chunk of the head is missing on the front. The idler gear was completely stripped in the head due to poor assembly. So FAILIER due to contamination/lack lubrication #4.

After removing the pistons i can rotate crank by hand smooth as butter. So now for my questions about this crank*

1) how the heck do you measure a destroyed spun bearing journal little rough for a mic
2) anyone know the surface hardening process used (nitr/induct/tuf)?
3) ^this will give me idea of how much i can get it ground down safely
4) i read a few people getting some took off and re nitrating their crank???? some say thats bad idea?some its not needed



*nitraded crank is surface hardened .010-.030 .....chrome hardened??? anyways im lost heres a link to some crap bout it

http://www.dsmtuners.com/forums/newbie- ... ranks.html

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neverlift
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Joined: Mon Apr 24, 2006 6:26 am

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depends on how bad the journal is on how much you need to remove. Some times you can catch it and just polish it out.

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lexcrob
Posts: 559
Joined: Mon Sep 22, 2008 7:38 pm
Car: I get a different ride faster than I could update this.
Location: Clarksville, TN

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*on a side note need a quick educated UPDATAED opinion on 248/248 cam set ups* found guy makin 160 NA with intake set 3.5 teeth retarted* (got .5 teeth by just notching out cam gear..........WTF

also read ".008 two human hairs on cam adjustment is 1 degree !!!!! (im thinking even chain slack variation would cause variation if thats a fact even hot engine cold engine scary stuff eh.....ill stop there beyond me!!!!






On to the point of the thread here : .... couldnt resist spreading the snake oil??? i read on forums.

Ill assume ka cranks are induction hardened seeing people get away with grinding it down. Suppose .010-.030 depth hardness so if out .030 then scrap. I could get it welded or...chromed>>(not common expensive...not done anymore??) but i guess thats a hit or miss kind of thing.

Weird how much info there is out there on crankshaft "hardness and all that annealing .....over my head.


Ill let you guys know whenever i do!


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