I'm about ready to send this thing to the junkyard. I've had the motor out 3 times now and still have oil pressure issues.
  Runs perfect but has inadequate oil pressure once warmed up and the timing chain starts rattling when you get rpms up to about 2500. I've replaced timing chains and tensioners twice, oil pump twice, and on the last tear down I plastigauged every single main journal, rod journal, and cam journal. Everything was within spec or service limit except for 3 cam journals ( they were past the service limit). I used a machinist straight edge and some 220 sandpaper to tighten up oil clearance on the tight side of the spec for the 2 front journals and the #2 intake journal. I also found a slight crack in oil pump base causing oil pump to have gap in between it and the block so I replaced..... again.

  Fresh oil and filter, got it fired up last night. Ran 70 psi idling at startup then slowly dropped as it warmed up again. Got to where it was at about 10-15 pounds idling and |removethispart|@ 4000 rpm where I believe the spec says It should be 65PSI warm it's barely |removethispart|@ 40psi. That's when I can revv it up and get the bad cam chain rattle. This makes no sense to me. Only thing else I've noticed is while pre-lubing there's a big stream( out of a 3/8" hole in the block right next to one of the front main journal bolts) of pressurized oil that dumps out of the front of the block that seemed odd to me. Not sure if that's a return passage dump for oil pump pressure relief valve when it's cold and |removethispart|@ high pressure or maybe something wrong.

 Does anyone have a clue of what in the world I'm missing?

 Any aftermarket 2nd timing chain MANUAL tensioners available out there? Or a way to build one with a ratchet mechanism like the lower? I think I have enough oil pressure to keep it alive for a long time if I could just keep that dang 2nd tensioner tight and not oil pressure dependent.

 PLEASE help with any ideas or thoughts on building a manual tensioner. ( I have several 1rst and 2nd chain tensioners laying around to build an experimental Frankenstein tensioner).         

As far as I'm aware the pressure relief  valve is on the pump itself - I believe that 3/8 hole hole may be missing a jet (or a plug) - is it on the front of the block just over the crank timing chain pulley?

 Yes, sounds about right off memory. A flow restricting jet missing would make sense. Do you know of any diagrams or part #'s? Thanks for the response! You've given me some hope at least.   

I don't have access to the parts manual right now, but, I have a recollection of something in that position, and the FSM shows the main oil galley in that location - if you have the front cover off and you can find a long thin rod (say a welding rod) insert it, into the hole - if it goes all the way down to the back of the block, it's the main galley - and it may be a plug that is missing.

I'll take a look at the parts manual when I get the chance (during the course of the morning) and get back to you.

|removethispart|@ work now but I'll start tearing back down asap to see. Thanks for the help yet again and let me know if you find anything. You're awesome!

Right on guys... Way to help out!

-Eric

There's no jet there, don't know what I was thinking of - there is a plug for the oil galley, above and to the right of the crank, and the oil way for the tensioner, which is above and left of the crank.

 So just to be perfectly clear, your saying I can plug whatever oil passage we're talking about. Whichever oil galley (left or right of crank) that is unrestricted? I just want to know exactly what you mean before I tear this damn thing down for a 4th time. Thanks!   

I'd rather you took a picture so I can see exactly what you're dealing with before I tell you to plug it - but - as far as I can tell there should not be an opening in front there with pressurized oil spraying from it.

 I have company now and a few too many beers so I'll try to yank it out tomorrow and get a pic posted tomorrow evening or no later than Monday. AGAIN, THANKS FOR THE HELP!

I'm pretty sure it's the little hole right next to the front main bolt in picture.

  I just removed oil pump chain and prelubed to confirm for sure, that hole has a pressurized blast of oil pressure at all times. It's definately not just draining back from the top somewhere.  Looking |removethispart|@ the service manual oil passage diagram It's hard to see but I think there's only an oil supply passage for the lower tensioner on that side. I would think that hole is either the lower tensioner "exhaust" hole or it's some sort of breach in the oil galley supply to the lower tensioner.

 Anybody know for sure exactly what this hole is and if it should be plugged or not?       

I was thinking front of the block not bottom - I don't know what that is, but, I doubt it's an exhaust for the lower tensioner/adjuster - more likely a drilling to feed it that should have a plug, but I'm just guessing.

 I have nothing to loose at this point so I'll plug it and see what happens. Thanks for the opinion.

Is it threaded?