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Old 10-30-2012, 02:57 PM   #163
Scooby Specialist
Member#: 242700
Join Date: Mar 2010
Chapter/Region: Tri-State
Location: Pittsburgh, Pa
2015 Impreza Wrx


Dividing into 2 sections: Block & Heads


Well to start things off, this has been a huge learning experience for myself and there has been a lot of work done to make sure we can make the power this setup is capable of and hopefully someone can take something away from my experiences through this very involved build :-) On to the info!!!

As those of you that have followed the build thread so far, the engine experienced a failure that involved one of the intake camshafts grinding through a bucket which then broke a valve stem and locked the valve in the open position loosing compression...

After finding this out seeing the metal pieces throughout the engine, we decided to tear down the shortblock as well to make sure nothing got damaged and be cleaned...

After tearing it apart we found a few problems with the block:

1. The block mains were stretched out .005"
2. The connecting rod bushing were extruding from the rod
3. The wrist pins were slightly bent

The use of the OEM case bolts caused the case to stretch and try to separate but probably the most interesting things were the bushings being pushed out of the rods and the bent wrist pins but I guess the head failure was somewhat of a blessing because we were able to fix the problems before something more serious would happen

Another thing that I became aware of was that I am in-fact using a 704 casing but bcz of time I had the block build, I was almost positive that I was using a 703 casing but thankfully after almost 8k miles on this block, the stock sleeves look brand new with no signs of abnormal wearing or cracks through the inspection, testing and reassembly process that I will cover next!

After finding this out, we took the following steps:
1. Machined the block halves and line main hone with upgraded ARP case bolts
2. Install new main bearings w/ clearances ranging between .0026 & .0028'
3. Install new rod bearings w/ clearances ranging between .0023 & .0024"
4. Honed connecting rods & installed new "classified" high quality bronze connecting rod bushings
5. Installed new CP piston ring set
6. Installed upgraded CP "Tool Steel" wrist pins(These are not the same type of wrist pins that came with my pistons)
7. Fresh cylinder hone using torque plate and ARP L19 head studs
8. Fully balanced rotating assembly

Now this all of these issues addressed the shortblock is ready to be installed and attached to the heads which I will put an update about shortly!!!

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Last edited by baseballdbk1; 10-30-2012 at 03:33 PM.
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