RB20DET block question(s)
So I am currently rebuilding an RB20DET and have come across what appears to be machining like cuts on the underside of the block where the crank rotates. At first I thought it could have been the crank rubbing but after further investigation I realized that (A) the metal on metal if starved of oil would appear to be far more violent and less controlled and (B) the type of finish indicates that it has been milled in. I also thought that the previous owner could have run an oversized crank (stroker) but I am still trying to check up on serial numbers of parts. Due to the possibility of it being stroked I also measured out the cylinders to see if it was bored out or anything and the measurements are coming to just about manufacturer spec.
You can see the machine marks I am talking about in the bottom left quadrant of the cylinder. The marks are all in the same position on all cylinders.
Also, the crank shows the same type of machinelike made marks which is leading me to believe that the crank was machined to be rebalanced. So if the crank is stock and just rebalanced why the machine marks on the block? I've looked at numerous RB threads specifically 20, obviously, and have not seen this or read anything about this.
With that said my question(s) are:
Why would this be done?
What kind of purpose would this serve in terms of performance or maintenance?
Other than skylineforums is there anywhere else I can look up serial numbers without having to contact Nissan and jump through hoops to get answers?
Any help is much appreciated. This is also my first post on zilvia so I couldn't decide on whether or not I wanted to put this in the build thread. It would be nice if im just a noob and there isn't anything wrong or the machine marks are something to be happy about.
|
02-06-2014, 11:19 AM
Linear Mode
