Subiesport Magazine - June/July 2008 - (Page 58)

2007 LEGACY GT PROJECT 36. Our fresh short block from Subaru. You can buy a newly built STI short block straight from any Subaru parts department. Since we are using forged pistons, we will have to remove the stock slugs from this block. 37. To remove the pistons, ﬁrst remove these inspection covers with a 17mm star drive in the front. You’ll need an impact driver on the rear plates. Install the crank bolt and rotate the engine over with a 22mm socket so that the wrist pins line up with the inspection holes. Remove the wrist pin retaining clips with needle nose pliers. 38. Using a long screwdriver, push the wrist pin out from the opposite side of the engine through the inspection hole (there are inspection holes on both sides of the engine). 39. Pull the wrist pin free and continue cranking the engine over. The rod will push the piston out. 40. With the stock pistons out, push the forged units into place to check the piston to cylinder wall clearance. 41. Piston ring gaps: Your piston rings will grow when they get hot, so we will have to set a proper gap so that they don’t bind or let excessive oil by on cold-start. To do this, push the rings into the bore with a piston to make sure they are square with the bore all the way around. Then, use a feeler gauge to check the gap. The top ring on our engine was gapped to .22-inches and the secondary gapped to .18-inches. The oil scraper rings do not have to be gapped. 42. The ring in the bore. This is how you will check the gap. Once the initial measurement is taken (it should be very tight) grind a bit of material off, re-install the ring and re-measure. This is a long and tedious process. 43. A ring “gapper.” This is the proper tool for grinding off ring material to get the proper gap. Take your time and don’t grind too much off in a ﬁt of trying to get done faster. Doing so will remove too much material; then you will have to get a new ring and start over. 44. Your pistons should have ﬁve rings each; the top, secondary and three scraper rings. The top and secondary are self-explanatory. The scrapers have a top, middle and bottom. Slide the middle “sectioned” ring on ﬁrst. Then the bottom ring. The top ring will have a notched end on one side. Slide this one into one of the oil ports on the piston (small machined holes). This will keep the oil rings from rotating around on the piston. 45. Of course there is a proper tool for installing rings, but if you are careful you can slide the rings on with your hands. Do the secondary ﬁrst, then the top ring. Also, install a new retaining clip into the inboard side of the piston. Once the piston is in the bore, there is no way to get to the inside of the piston. If you forget this clip and start the car, the wristpin will slide out and bad things will happen. 46. Installing the pistons. Lubricate the rings and pistons with fresh motor oil. This will make everything easier to work with, will save parts from damage, and reduce bore scoring. Note: Most pistons have markings on them, which tell you which side of the piston is up, especially with offset wristpin-type pistons. Installing the piston incorrectly can result in skirt slap and excessive noise, requiring you to completely take the engine apart for a do-over. 47. To install the pistons into the bore, you must ﬁrst compress the rings with a ring compressor. This is a specialty tool that you can get at most auto parts stores and Sears. 58 JULY 2008

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Subiesport Magazine - June/July 2008 Contents Editor Letters Readers’ Rides Subaru News Fresh Squeezed Hell's Legacy Under the Radar Project GT Rebuild New Engine AVO 420 Turbo Perrin Intercooler Rally Like a Rockstar Rally Jordan Adventure WRC Rally Argentina WRC Rally Jordan WRC Rally d’Italia Sardegna Where to buy Subiesport WRC2008 Debut Rally America: Olympus Ad Directory Rally America: Oregon Trail Spotted!

Subiesport Magazine - June/July 2008

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