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I understand that lifters are oiled/via oil and pressure, and different lifters have different pressures and bleed out, etc. But how would lifter affect the overall oil pressure, Isnt it measured via an oil passage after the bearings that travels up throught the heads, then to the lifters, meaning pressure would be read prior to the oiling of the lifters. I undertand that pressure = measure of restriction. So i guess i can see where a certain type of lifter could cause some degree of pressure variance..
Think of a garden hose, connected to a spigot with water being supplied at a regulated 65psi. With a nozzle on the hose and the spigot fully on, you will have 65psi in the hose if the nozzle is closed. But once you open the nozzle past a certain point (when the amount of water leaving the nozzle exceeds the amount being supplied by the spigot), the water pressure inside the hose starts to drop, and continues to drop as you squeeze the nozzle open more.
By analogy, on most engines, pressure is regulated at the pump by a pressure spring that allows oil to bypass at a certain pressure. But that pressure can only be achieved and maintained if there is sufficient pump volume to exceed the amount of oil being bled off: out the sides of the bearings, around the lifters and through the pushrods to the rockers, etc. So, anything that allows oil to bleed out of the oiling system faster will tend to cause a pressure drop in the oil galley, simply because the oil pump isn't really keeping up. A set of 16 lifters, each with an extra orifice to oil the pin, will bleed off a decent amount of oil. Additional bearing clearance will also allow more oil (of the same viscosity) to bleed out the sides of the bearings. So, these things will tend to cause a lower oil pressure in the oil galley.
That's one of the reasons that high volume pumps are utilized with racing engines, which generally tend to have looser tolerances. It's also the reason that looser clearances call for thicker oil. This is pretty elementary stuff, actually.
Think of a garden hose, connected to a spigot with water being supplied at a regulated 65psi. With a nozzle on the hose and the spigot fully on, you will have 65psi in the hose if the nozzle is closed. But once you open the nozzle past a certain point (when the amount of water leaving the nozzle exceeds the amount being supplied by the spigot), the water pressure inside the hose starts to drop, and continues to drop as you squeeze the nozzle open more.
By analogy, on most engines, pressure is regulated at the pump by a pressure spring that allows oil to bypass at a certain pressure. But that pressure can only be achieved and maintained if there is sufficient pump volume to exceed the amount of oil being bled off: out the sides of the bearings, around the lifters and through the pushrods to the rockers, etc. So, anything that allows oil to bleed out of the oiling system faster will tend to cause a pressure drop in the oil galley, simply because the oil pump isn't really keeping up. A set of 16 lifters, each with an extra orifice to oil the pin, will bleed off a decent amount of oil. Additional bearing clearance will also allow more oil (of the same viscosity) to bleed out the sides of the bearings. So, these things will tend to cause a lower oil pressure in the oil galley.
That's one of the reasons that high volume pumps are utilized with racing engines, which generally tend to have looser tolerances. It's also the reason that looser clearances call for thicker oil. This is pretty elementary stuff, actually.
I answered my own question in my last reply lol, but thanks.
OP. When I replaced my OEM balancer I noticed an end seal on the snout that sealed against the rotor and stator of the stock pump. Couldn't find much about it on the forums or internet but it looked like it sealed up and side clearances. The IW HB I got had a thicker wall on the snout requiring a larger timing cover seal so the original seal wouldn't fit. Called IW and they said "it's not needed...but some people use it"....Found that a pretty odd statement since it looked pretty important but so far so good on oil pressures. Suspect the IW snout is .030" longer than OEM so the face of the snout replaces the function of the seal.
Not sure if any of this applies to your setup but making sure the right balancer was used might be a good idea. A shorter snout might not seal the ends of the pump, or maybe the seal was left off the snout.
Threw in some Mobil 1 10w40 (before I came back to read the responses... and thank you all for chiming in) and my pressures are looking better. I idle hot at 18 PSI (much better than 6psi I saw with the melling high pressure pump!). I cruise at 36 PSI now.
I can't confirm my WOT pressures because I have a significant oil leak I am trying to track down.
I have pulled the oil pan/front cover off 4 times in two weeks!!!!!!!! I can have the entire thing pulled off in two hours now in my garage due to repetition. Whole other big headache worthy of its own thread. Still can't figure out what the deal is so I'm giving it to a shop to do when I find time.
Interesting read here about motor oils and why thicker or heavier oils is not necessarily a good thing.
Start at item 29 as a example. https://540ratblog.wordpress.com/
Interesting read here about motor oils and why thicker or heavier oils is not necessarily a good thing.
Start at item 29 as a example. https://540ratblog.wordpress.com/
That is a very interesting read. I have a link to that webpage on the homscreen of my iPad. It's like the Bible of oil testing.
BTW: here's a very timely thread on this very forum, posted up just today by the very came guy:
Didn't need to go to a shop. I got lucky and found a small crack in the oil pan. All fixed up now and took the car out for some driving. No WOT pressures to report yet because the roads are wet but 1/2 throttle pulls I see oil pressures into the 40's.
Also interesting is that my oil temps seem to stay right around 215 degrees now (perfect).
04-21-2017, 12:37 AM
