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Next, the ring gaps are measured with a feeler gauge. A file is then used to adjust and fit the rings. A hand file is used in order to control the ring end gap precisely.
The ring ends are filed a little bit at a time to get the gaps perfect. This is a tedious and time consuming task, but one that will greatly affect the performance of your build. Take your time and file a little bit of material off at a time. You can always remove more material, but you cannot add more material!
With all the bearings in place this bore gauge is used to measure all the bores, the mains and all the rod bores as well.After measuring the bores Martin uses a micrometer to measure the pistons and the crank journals. The numbers are subtracted to get the piston to wall and the rod and main bearing clearances. Even though you might use a good machine shop, it’s very important to confirm you clearances because mistakes are made and they should be caught now, not on the track!
Our SR20 build will be using King XP bearings for the rods and mains. The XP bearing is a hard, heavy duty bearing with a lot of load carrying capacity.King Bearings XP series have many built-in features that help with strength and overall bearing performance. Their pMax Black tri-metal structure is built to handle increased load capacity. With their patented SecureBond micro-etch process that improves multi-layer adhesion and integrity, you get a stronger copper intermediate layer and overlay.
The unique 90* U-Groove shape helps with load distribution and durability at high RPM’s without any detriment to oil flow and lubrication.
When we build an SR20 engine we always use the bearings from the 54C series GTI-R block. The GTI-R bearings are wider with greater load bearing capacity.The GTI-R main bearings also have these extra oil feed holes so you can groove the main saddles and get more oil flow to the rod bearings. We didn’t bother to do this to our G20’s motor because the engine isn’t stressed enough and doesn’t run much boost.
The stock engine didn’t have bearing issues and we figured that just the use of King XP bearings in the wider GTI-R configuration was enough. When you don’t groove the block, the extra oiling holes just are not used. Nothing is harmed or changed.
