Proper way to disable the oil bypass - AGAIN

[My427stang]

I always check pumps and also plug bypasses, although my 489 center oiler is just tightly shimmed.  I used to do it that way because it was faster, functionally it's much tighter than the oil pressure would ever push on it

[Qikbbstang]

Autoholic your concern over  oil pressure loss through long and complex pathways to me seem overblown. Based on a past discussion/thread on the duration that a remote oiling system  (Accusump) can maintain oil pressure w/o oil from pump.   I concluded the typical FE oiling system only consumes a tiny fraction of those stated numbers in the Muscle Parts Catalog: "70-80 psi 22gpm at 4,000 rpm" the secret is they use the words: "has the capacity" in the Muscle Parts paragraph.   
   Back in the early 70s I installed a windage tray and that pump in my otherwise stock 390GT without any issues.  I believe vintage Ford oil pumps by design have huge capacity, but go into bypass (internally within the pump) in short order. This reminds me of a friend that seriously over "shimmed" a 2.3Ltr oil pump and promptly blew out his oil filter just cranking the motor to start it.
   The typical passages in an FEs oil system are far from restrictive to the nominal amounts of oil normally flowing through them, ditto on properly sized remote oil systems.

[turbohunter]

Autoholic your concern over  oil pressure loss through long and complex pathways to me seem overblown.

Pot meet Kettle   

[Autoholic]

Autoholic your concern over  oil pressure loss through long and complex pathways to me seem overblown.

The rear pressure relief valve would seem to be a benefit if you put a high pressure spring in the regular oil pump, so that the regulation is done at the end of the oiling system, but based on the tests I've done with oil pressure gauges at various spots in the engine, there isn't more than about a 15 psi drop off front to back, so as long as you have sufficient pressure up front I'm not sure that the rear valve is needed. 

I would believe Jay if he said "isn't more than about 15 psi drop off front to back". I could easily believe 10-15 psi drop in pressure from the front of the engine to the back. But, I also pointed out that on an application which uses a remote oil filter and oil cooler, that drop could be another 10-ish psi. That is a conservative estimate as well. You could probably lose 5-10 psi just in the oil cooler at a minimum, with a tiny oil cooler. That's not overblown, it comes from hands-on knowledge of pump losses, although done with water which is a pretty good baseline for any comparison due to being the standard at which viscosity ratings are based on. So at minimum you're seeing 10-15 psi drop in the engine itself and if you have an oil cooler with remote oil filter setup, you could be seeing another 10-15 psi drop before the oil even hits the engine. If you can seriously say that my analysis is flawed, I'd love to know your reasoning. It's not that I think I know everything (I don't), I just want to see the logic behind your viewpoint.

So, please show me how I have overblown the issue. I'm saying 10-15 psi drop in the engine and another 10-15 psi drop outside the engine if you have a remote oil filter and oil cooler setup. Under said setup, there could be 20-30 psi drop by the time the oil has reached the rear mains at peak operating conditions.

I fail to see the importance of bringing up the accusump thread in this context. We're talking about pressure drop from the pump to the rear mains. The only time pressure drop was mentioned, was over oil filters and even then, no one put any numbers out there. The whole problem in the thread was you not understanding the purpose of an oil accumulator in a wet sump system and having a hard time wrapping your mind around the flow rates of the pump. One of the things I do see more than once, is you talking about a delta pressure at the filter. This means there would be a pressure drop across the filter (naturally) which only supports my statement. So your own understanding of pressure drop in previous posts is actually fighting against your questioning of my estimate.

My intent, is only to show that there is a pressure drop that needs to be taken into account. There is more than one way to skin a cat and Ford must have figured that for the FE, the best way to manage oil pressure was at the back of the engine. There is a difference between giving a long winded explanation and blowing something out of proportion.

[IDOIT4SPEED]

we must cast a careful eye on all parts of the oil system, all the time.  to do any thing less is to invite disaster.

[jgkurz]

I never imagined there could be this much discussion around the oil bypass. I've learned a lot and appreciate each and every response. Thank you.

[C6AE]

Thinking out loud on the "side-oiler"
My own observation is that a lot of "top oilers" cracked the bulkhead at the drilled oil hole from cam to crank. It seems the combination of the cast groove around the cam bearing bore and the drilled hole (which is larger on the 427's) weakened the bulkhead and may contribute to block failure at high loading. An elegant solution is to just eliminate the cast groove and the drilled hole. Which is the side-oiler.
(Of course the "cammer" was in the works then and that oil rifle detail solves both problems.
For me, when searching for a good 427 block, that "crack" was the first thing to inspect, and I saw more than one)

The "extra" relief valve may be as simple as an over pressure device. Oil filters will fail at pressures over 100 psi.