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Discussion Starter · #1 ·
Is it reliable to overhaul a K20z3 Civic Si 2007 engine crankshaft, pass the STD measurements to 0.25 and use 0.25 connecting rod bearings?
Sorry for the bad English, I'm using the translator, I hope the community can help me, I'm from Brazil and I'll follow the forum, greetings and a great 2022, prosperity!
 

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Is it reliable to overhaul a K20z3 Civic Si 2007 engine crankshaft, pass the STD measurements to 0.25 and use 0.25 connecting rod bearings?
Sorry for the bad English, I'm using the translator, I hope the community can help me, I'm from Brazil and I'll follow the forum, greetings and a great 2022, prosperity!
Honda crankshafts (in my opinion) are garbage once a rod or main bearing is spun or the journal is damaged beyond polishing. I have seen multiple engines put together with .25 oversized and another bearing spun within the first hundred miles. This could of been due to improper building but I doubt it
 

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Discussion Starter · #4 ·
Honda crankshafts (in my opinion) are garbage once a rod or main bearing is spun or the journal is damaged beyond polishing. I have seen multiple engines put together with .25 oversized and another bearing spun within the first hundred miles. This could of been due to improper building but I doubt it
I had the same opinion, these crankshafts are fragile like the subaru that have a narrow bearing, my preparer said the same as you, after a certain run-in the car turns bearing again.
 

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I had the same opinion, these crankshafts are fragile like the subaru that have a narrow bearing, my preparer said the same as you, after a certain run-in the car turns bearing again.
Unfortunately the best option is to find a used oem crank that has all green journals or buy a new one which is about $1000 usd and you can usually buy the entire engine for little more than that.
 

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if the crank journal machining is done properly, it will be reliable. Be aware that the journal diameter tolerances are extremely small. Not everyone can actually regrind them that well. As far as I know there is only one oversized bearing size availability. The journal has to be ground to the new actual bearing diameter as installed in the actual engine.
Next, you need to sort out what caused the spun bearing in the first place.
Otherwise is happens again.
 

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Discussion Starter · #7 ·
if the crank journal machining is done properly, it will be reliable. Be aware that the journal diameter tolerances are extremely small. Not everyone can actually regrind them that well. As far as I know there is only one oversized bearing size availability. The journal has to be ground to the new actual bearing diameter as installed in the actual engine.
Next, you need to sort out what caused the spun bearing in the first place.
Otherwise is happens again.
I believe it was because of using honda 0w20 oil instead of motul 10w40. I'm looking for a new crankshaft but here in Brazil, the prices are R$ 5,600, used is not found because this copy had few units around here, so I would like to recover this one but according to the opinions of friends here on the forum it will not be possible .

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why not, crankshaft journals are commonly reground for race engines when they are blueprinted to work with a single bearing size.
You only need a (very) good workshop to do the work. That is all. Tolerances are so small, you need a workshop with temperature control and have crank and block temperature stabilized. If this is omitted, you will be in trouble as as little as 10°C difference will consume your bearing clearance tolerance.

I have just seen that King bearings also offers three sizes in their oversize range:
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Discussion Starter · #9 ·
why not, crankshaft journals are commonly reground for race engines when they are blueprinted to work with a single bearing size.
You only need a (very) good workshop to do the work. That is all. Tolerances are so small, you need a workshop with temperature control and have crank and block temperature stabilized. If this is omitted, you will be in trouble as as little as 10°C difference will consume your bearing clearance tolerance.

I have just seen that King bearings also offers three sizes in their oversize range:
View attachment 107162
Here we have the King and Acl bearings that provide the measurements for the K20, I will use the King ones if I choose to rectify the crankshaft, but I had information that with a certain running-in the problem returns, I would like experiences of users who rectified and are running to this day or not.
 
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