[Goatracer1]

I remember a question on here about an oil plug behind a core plug in the back of a V8 block. If the plug was missing the oil pressure would be low. Well I just got my 389 back from the machine shop after 8 months. There are NO pipe plugs anywhere in the block. He left out every one, oil and water. I want to make sure I get them all. If someone could remind me where that rear plug is it would really help.

[Schurkey]

Are you thinking of the plug in front of the distributor gear? Most folks install a vented plug so that the distributor gear gets sprayed with oil. Also prevents sludge build-up in what would otherwise be a dead-end oil gallery.

[steve25]

The two front cup plugs behind the Cam gear are 9/16”.
There is a lip in each passage that will stop you from driving them in too deep.

Be sure to stake these over a bit with a punch so they can’t pop out.

Many folks for added insurance chose to drill and tap these for 3/8” pipe plugs.
You must be careful and not drill and tap too deep because if the passenger side pipe plug goes in too deep you will restrict a much needed oil feed passage.

It’s best to use a shallow Aluminum hex seat pipe plug at least on the passenger side.

If you do this be sure to tap just deep enough to both allow the plug to seat and fully seal and also to have both passenger and driver side plugs clear the Cam gear and chain.

If you use a harden pipe plug for the rear of the oil galley you will not be able to drill it for a .030” hole to oil the dizzy and Cam gear.
In this case use a Aluminum plug or take a hack saw to the threads on your hard steel plug.

Not only does this mod oil things better back there, but in terms of priming the oil system for first start ups helps to get air out of the system and you will find that your lifters will pump up faster and move oil up to the rockers faster in turn.

Just cut deep enough to break into the end of the threads by the width of your saw blade and this will then lube both gears.

If you use a Aluminum plug here be sure to blue Loctite it.

There is a pipe plug on the top side of the motor below the dizzy, is that one removed also?

[grivera]

Below is a good pic of the rear plug and also a link to a thread about the front galley plugs:
https://forums.maxperformanceinc.com...d.php?t=632286

Butler sells a drilled plug to provide more oil to the distributor gear in case you don’t have the ability to drill yourself: https://butlerperformance.com/i-2498...pio-pp475.html

[mgarblik]

If your block has not had it's final cleaning process performed yet and the cam bearings have not been installed, I strongly recommend direct tapping the front oil gallery plug holes for screw in plugs. If already prepped for assembly, make sure the front plugs are staked in securely in at least three places. I have seen these plugs pop out, resulting in very low to 0 oil pressure. It depends which one comes out.

[78w72]

Ive heard of & seen the passenger side oil galley plug be left out by builders that dont know pontiacs very well. I bought a car a few years ago that had a fresh build high dollar 455/474 stroker in it, the shop & owner couldnt figure out why it ran so rough, would misfire & sputter & backfire... gauge showed good oil pressure. he was selling the car due to a divorce but tried everything & numerous "mechanics" to get it running right then finally threw in the towel.

Got it home, did some basic testing for firing order, timing etc, everything was ok, so i finally pulled the valve covers to inspect rockers etc... started it up & instantly saw the passenger side rockers barely moving, knew right away that it was wiped cam lobes or that oil galley plug was left out. Cam looked good visually so pulled the dist & sure enough the plug wasnt there... was able to carefully install it through the dist hole, fired it up & it ran great! I pulled the new E-heads heads & other external parts & sold the short block to a guy that kept in touch & sent videos with his new parts on it, said it ran great. I kept all the parts for a new stroker build using a 400 block & forged butler rotating kit. The 455 had a cast stroker crank & KD hyper-U pistons that i didnt want to use for my build.

That rear oil plug can cause running problems but the engines oil PSI should be good without it, just low psi on the pass side lifters.

[Goatracer1]

Thanks. I read everything and didn't know it was going to be this complicated. I'm glad I asked.

[steve25]

It’s not complicated if you just want to go with stock as countless other of rebuilt Pontiacs have use such a route and lived just fine for decades.
The main thing as talked about here a few times is to stake those two front passages if you go with the stock metal plugs.

[pupuliyak]

Ok so I've read everyone's preference and opinions on gallery plug and pressure requirements for different duty but unfortunately none of these are MY dilemma. 455/474 Stroker no bypass valve, blocked off by Butler plate double remote filters with 170° thermostatic controlled oil cooler w/Fan and a ONE PIECE rear main seal, pretty sure there is nothing better to seal crank, as far as I know anyway. I have a Mallory Comp 9000 dist. so not too worried about the gear. I know that the pass galley plug is in it and NOT drilled. OK so, it's a brand new STOCK melling oil pump and upon startup there's over 80psi of oil press with 5w-30 royal purple. Now I know what your thinking, but it's not ok to push oil past the main seal and on to my FST twin disc clutch or even into the bell housing at all $700+ for that unit plus aluminum flywheel and hyd. throw out.
Soooo, first what is causing excess pressure? after warm up 35lbs. Second, would drilling 0.30 hole in galley plug drop pressure any? Obviously there are many knowledgeable folks on this site sooo, what do you think.

[steve25]

80 cold psi out of a 60 psi pump is very normal and will not blow out your rear main seal.
Many folks here would near kill to have 35 psi of hot oil pressure at idle!
What might concern me is how close your oil cooling system will hold the oil temp to 170.
In my opinion 170 is too cold and I am sure others will concur.

Also I would hope you have implemented a oil temp gauge?

[ponjohn]

Do you install the plugs with blue loctite?

[P@blo]

This has come up recently in another topic. A 60 psi oil pump does not mean the entire engine sees this as a static oil pressure everywhere all the time. You have to consider the frictional losses from X diameter feed lines and where it is feeding off (distance from the pump). Pontiac engineering takes care of this for us thankfully.

My little sbc makes me shake my head at idle but it's still running fine. Had to stop looking...

[Bill Hanlon]

Originally Posted by pupuliyak

Second, would drilling 0.30 hole in galley plug drop pressure any?

You probably meant to say a 0.030 hole, but just in case do not drill a 0.30" hole in the plug.

[Dragncar]

I have staked them in the past and filled it up with JB weld. Never have had one come out.
Last motor I tapped for plugs.

[pupuliyak]

Ok, so I don't (yet) have a oil temp gauge just the 69 TA oil pressure stepped gauge, and there could be an incorrect reading from the passage near the distributor but it stands to reason that if it were not accurately showing 80+ pounds at start up it should not push oil past the rear main with that seal.
I had the ProGram 4 bolt caps line bored and I don't believe they did a bad job, (reluctant as he was) so the bearing tolerance is not causing a restriction. I just can't help feel that something IS. Is there bypass valves in the filters? front one seems to leak too. I've had friends say that there engines like to run hot, my thermostatic fans are on at 175 and off at 160 and I have reversed flow from water neck to rear of heads to counter those "tiny bubbles" that occur over combustion chambers if it weren't for the $1100.00 wizard radiator I believe it would STILL run at 210°. aAs far as the 170 temp for oil, to my knowledge the fan has yet to come on, what temp do you think it should be?
BTW, it is a full roller lifters and rockers with 1.65's on the intake and 1.5's on ex.

[pupuliyak]

Yes Bill I did mean to say 0.030 sorry fat fingers and slow brain.

[steve25]

What makes the stock steel front plugs blow out on builders be they pro or not is this.
If you drive these plugs or any plugs in for that matter with a socket as many do and that socket does not closely fit the ID of the cup then you can end up stretching the plug.

Once that takes place then some amount of radial pressure that is supposed to hold the plug in it’s hole is lost.

Even some folks perform the staking process wrong and have made the stake pinch in on the rim of the plug instead of impeding its exit from its hole.

[pupuliyak]

First of all I'm still the site newbie so having some difficulty finding the right button to thank all who have posted with regard to my dilemma.

Secondly let me rephrase the questions I have, will drilling a 0.030 hole in the galley plug for more oil to dist. gear lower the oil pressure? And apparently what is a stock oil pump pressure? I'm pretty sure the one I bought is 40psi. So 80 psi from it is twice what it should be. Are there by-pass valves built into oil filters? Because removing the oil filter bracket with the obvious by-pass valve is kinda self defeating if there is. Another question would be with two oil filters what would you consider appropriate for first filter microns and second filter microns?
Again thanks for your comments I do appreciate them.

[Dragncar]

You will not see any oil pressure drop with a .030 hole, none.
But, any engine that someone went through the considerable time and expense to go with billet caps should have a 60lb pump.
Billet caps on a 389 is kinda strange though. No need for them at all IMO. Unless the block was missing them.
Leave the by pass in the stock filter housing.

[242177P]

"Pushing oil past the rear seal", I've heard far too many people say that. But the seal doesn't see any pressure - at least as far as oiling system is concerned. Only thing doing any pushing is crankcase pressure. Blowby and/or evacuation. HTH.