I will add some thoughts.. based on what I do in the shop at least a couple times a month. With the engine on the stand, here is how you fill the oil pump so it will prime right away. Put the damn vasoline away.. no kidding, a TA assembled pump that had unknown to me, sat 4 for years, full of that junk, cost me a motor last year. Assemble your pump dry.. and I will tell you, put the end play measuring tools away.. The only thing you want to measure is the new pump gears.. insure they are the same length, correct as required... as for measuring end play, your more likely to make a mistake in measuring that will lead to too much end play, than you are to accomplish anything good. Use the test assembly method. The correct gasket/shim setup for pump clearance is the one that allows the pump to spin freely when it's all tightened up. Simple, done.. don't over think it. Now, you have a nice, dry pump assembly that spins freely.. Bolt it up to the engine, and put the oil pan on. Because I block the hole in the DS deck on a 455 block, or both in a 400/430 if we are converting to pushrod oiling, I pre-lube just the shortblock. The only motor I prelube with the heads on, is a 400/430 that is maintaining thru the block rocker oiling. To insure it primes up right away, do this.. Flip the block over on your stand, until this hole in the pump cover is vertical.. That's the output from the pump chamber to the filter, we are going to squirt oil in this hole, while spinning your priming tools backward (counterclockwise) with your fingers. It takes just a few squirts of oil, until you will hear the gears go "glug glug glug" as they get coated with oil. Now..spin the filter on, turn it over, fill the oil pan, install the lifters, and then prime just until the drill slows down.. If you sit here and prime and prime, all your accomplishing is to wash the good prelube out that you should have used on the cam, rod and main bearings (Clevite bearing guard or similar). When installing the valvetrain components, you lubricate them well.. they will oil within seconds of the engine starting and coming up to cam break in, or warm up speed. I recommend Lucas engine assembly lube for all valvetrain components.. With used TA roller rockers, flip the shaft upside down and squirt break in oil into the holes in the pushrod cup.. this will prelube the rocker.. don't touch them with new rockers, just lube the pushrod cup and the valve tip.. they come pre-lubed. Don't forget you have to plug the hole in the deck surface to do this, without taking a bath in oil.. See the oil mods thread for that procedure. Again, I can't stress this enough.. I don't care what anyone says... vasoline has no place in your engine, and IT WILL partially plug the filter, until the engine warms up enough to melt it. And on first startup, that is not when you want to be reducing oil flow. When given a pump assembly that is full of vasoline, I get the heat gun out and melt it out.. The one time I did not do that, cost me over 1k, and the customer several weeks more wait time. That motor lost the cam bearings, and number 5 main on startup. Number 5 main is the last to get oil, without a equalization line, and the cam bearings are absolutely critical to have oiling immediately once it starts.. a few seconds delay melting out vasoline is too long. If your installing a new pump on an engine already in the car, then simply oil the pump before installing it.. using the same method I outline above. Pre-lubing the engine is a requirement before start up.. PERIOD.. buy a pre-lube tool if you don't have one.. IT'S NOT OPTIONAL.. So the argument "We want to make sure it has oil pressure when it starts" is a silly one. Educate your customers.. Rule of thumb on relief springs... always start with the stock, or "weakest looking" spring. A well assembled aftermarket, or properly ported stock pump assembly, rarely needs the white or orange spring.. (stock 455 or later universal cover respectively). Even with the .0025 to .0027 main clearances I often use. Rod clearance is not a factor on the ability to maintain oil pressure at low engine speeds to any great degree, that's a really all about lifter to lifter bore clearance, and main clearance, balanced against pump output at low rpm. For all street builds, and most race builds, desired oil pressure is between 75-80 at 6000 rpm, with the iron block. Use the thinnest oil you can, to achieve those pressures, and as Denny Manner said, "anything above zero" is fine for idle pressure. We like to see 10-20 lbs, which is fine, as long as it goes right up when you step on the gas. JW PS.. Let's dispel on old fable.. "Changing to a stiffer relief spring will not change idle oil pressure". With conventional thinking of how a pressure relief system works (relief stays closed until pressure is seen by the valve, then opens) one would deduce that would be the case. But, in reality, localized pressures in the pump assembly are much higher than you see on the gauge. This makes that relief valve oscillate, long before the "set point" is reached. Therefore, increasing the spring rate of the pressure relief spring, will in fact cause an increase in oil pressure, at all rpm's including idle. Try it for yourself.. add a 1/4 inch cap screw to the end of your relief spring, (Old KB trick)...or simply crank your Adjustable regulator all the way in.