For a street motor (drive this car to work every day), from what I have read .0015-.0020 (maybe .0005 more for the rear main journal) is good for all the crank clearances. I will be going through the motor soon, oil pressure is adequate from 1000 rpm and up, at about a 600 idle (TA 212), it almost hits the needle @ 0 lbs. I have done the oil bypass line on my last GS, it seemed pretty straight forward/fun to do. I want to do it again. I will be going up cam-wise, something 240* duration @ .050/ .500 lift area. If I run the bypass line (I have to search around for line size specifics), should the crank clearances be the same, or different? Thanx all.
John, I would say the the clearances should not change at all. The lifter galley bypass isn't really necessary with the advent of TA's grooved cam bearings. The oil pump discharges into the passenger side lifter galley, and the oil travels across the front cam bearing to pressurize the drivers side lifter galley. When you wiped the front cam bearing, you starved the drivers side lifters resulting in noise on the drivers side. The bypass was good insurance in case you had some front cam bearing wear. TA's grooved cam bearings, if installed correctly should make the bypass unnecessary. I would install a fitting off the lifter galley to monitor oil pressure off the rear of the block instead. Just my .02
hello Thanx for the info Larry. I must be using the wrong terminology. I was talking about the line that goes from the oil sending unit hole right behind the front cover to the back of the block, not the line that connects the 2 lifter gallies in the back. On the motor I am talking about, I enlarged the passage from the sending unit hole on the side of the block to the #1 cam journal, then brought a copper line to from the enlarged/tapped hole to the back of the lifter galley. Oil pressure was good and quick in the morning. Thank you again.
OK, now I understand. I can see how that would work. I still wouldn't change the bearing clearances though.
John, I went and pulled this up from a page or so back.. The main galley bypass line is typically used with an external oil pump, or a motor that has race bearing clearances, and we want to run a lot of oil pressure. I have used it in milder engines, but recent testing, with tear-down after the dyno for inspection, shows that the line is not really required on a motor that does not have either large main/rod clearances .. (.003+) or runs a roller cam. This line is a must with the roller cams, and the external oil pump that you need to go with them. Big roller cams uncover the main galley, when the wheel section of the roller comes up past a certain point on the lobe. That being said, if you want to run the line on a milder motor, you can, but keep the main/rod clearances at right around .002. JW
