[MarkS57]

Originally Posted by chuckies76ta

I wouldn't use any heat on it, but that's just me. You can always use the oil filter housing location and remove it someday when and if you tear it down. Just remember andycrap that falls down the hole from removing the plug, will and could end up in the lifters. The oil line I believe is the feed to the lifters, Cam bearings, Mains and rods. It would only take one little piece of dirt to plug the orifice on a lifter and that spells trouble.

Good point, the only time I've done this is for a rebuild, not for a gauge install. The crap behind the plug can be ridiculous as I found out cleaning the oil galleries after removing the plugs.

[lust4speed]

Good point on the crud since this is right at the beginning of the oiling circuit.

Here's the easyout I use. The tip is 5/16" so it is lightly hammered in place for a snug fit.

[bhill86]

It’s a little tight with headers but if I were to use a T at the filter housing are those 1/8 NPT?

[b-man]

Originally Posted by bhill86

It’s a little tight with headers but if I were to use a T at the filter housing are those 1/8 NPT?

Yes you are correct.

[hgerhardt]

Originally Posted by bhill86

Can anyone help me out with the size of the square “head” needed to remove the oil plug by the distributor? Ordered a mechanical oil pressure gauge I’d like to plum there. I also picked up a 3/8 male npt to 1/8 female reducer. Does 3/8 sound like the correct size for there?

Thanks

It's been a while since I've had mine apart, but pretty sure it's 1/4" NPT.

The pic below shows a factory Olds gauge sender adapter (45-ish deg) into a 1/4-1/8 NPT bushing.

Also, as others have said, if your plug has never been out, there will be crud in that channel which could get dislodged and fall into the main oil gallery below. I'd wait until the next time you have the engine apart. MAYBE you could get away with using a turkey baster with a hose attached to suck out the crud/oil from the hole after you've removed the plug.

[Dragncar]

Originally Posted by 68WarDog

PB Blaster soak x30 minutes. Then propane torch until red hot, through some more PB while red hot(stand back because the PB sometimes pop). Hit with the Snap on plug removal with a 3/8 impact, and it will zip right out.

This works because when you heat the plug up it grows. Then when you hit it with PB it cools the plug down shrinking it. Gives you some clearance between the threads.
I do this all the time at work but with water as a coolant. I would not put too much heat on your iron block and cool it though. Might crack the iron.
Need to be careful.

When you put the plug back in I use a grade 8 Allen plug with a .030 hone in it to oil distributor gear. I drill almost all the way through with a 3/16 bit and finish the last bit with tiny .030 drill bit.

[Sirrotica]

Originally Posted by Dragncar

This works because when you heat the plug up it grows. Then when you hit it with PB it cools the plug down shrinking it. Gives you some clearance between the threads.
I do this all the time at work but with water as a coolant. I would not put too much heat on your iron block and cool it though. Might crack the iron.
Need to be careful.

When you put the plug back in I use a grade 8 Allen plug with a .030 hone in it to oil distributor gear. I drill almost all the way through with a 3/16 bit and finish the last bit with tiny .030 drill bit.

You're talking about the wrong plug.

He wants to remove the external plug on the outside of the block, next to the distributor. Not the galley plug on the inside of the block at the end of the passengers side lifter galley. Two different conversations going on, but the process works on either application.

[bhill86]

Well, last night I mounted the gauge and ran the copper line. I had enough to reach to the filter housing and there’s a little more room to work with so for now I’m going to plum it there I think. I just need to grab a T fitting to finish it. I may switch to near the distributor down the road if needed.

I know I’m opening a can of worms with this question, and it may be better suited for its own thread at some point but, assuming my factory gauge is correct do these numbers for oil pressure vs RPM seem in the realm of normal?

Oil is 10w30 on a chilly day in the high 40s. I kind of wonder how they might be different on a hot day. In a nutshell, last October my 400 (with about 4,600 miles after rebuild) was due for an oil change. My drain pan is a closed type with a hole in the middle so I didn’t look at the oil but there were some extremely thin flakes in the filter. Just a few. I decided to monitor it. A few hundred miles later, last week, I decided to change it again. There may have been some junk in the oil but I can’t be sure I cleaned the pan well enough and because of the pan design I couldn’t inspect it well. Filter was completely clean save for one similar flake. For now I’m just monitoring and plan to drain the oil in another couple hundred miles into a pan I can really inspect well. No noises but wanted to ensure the pressures in seeing at varying RPM are acceptable in the meantime. Also the reason for installing the mechanical gauge.

[25stevem]

Those pressure vs rpm numbers look fine to me especially if this was done with the motor fully warmed up and some temp in the oil, like after 10 minutes of driving at 35 mph.

[bhill86]

O yea it was well over ten minutes. I was probably driving around 40 min before I started taking pictures. Thanks for your insight. I’m hoping what I saw previously was a fluke

[bhill86]

Ok, mech oil pressure gauge is plumed at the filter housing with a Y. I only got about 15 min of driving in. I got rained on unexpectedly and had to go back home. Idle pressure according to the mechanical gauge is a touch below 15psi. Maybe 13-15.

For reference, motor was rebuilt 4600 miles ago and according to the build sheet from the builder my rod clearances were .0018-.0019, mains were .0021, .0019, .0023, .0023 and .0023. with .009 end play. Does that all seem to jive or is idle pressure a little low?

[JSchmitz]

Originally Posted by bhill86

Ok, mech oil pressure gauge is plumed at the filter housing with a Y. I only got about 15 min of driving in. I got rained on unexpectedly and had to go back home. Idle pressure according to the mechanical gauge is a touch below 15psi. Maybe 13-15.

For reference, motor was rebuilt 4600 miles ago and according to the build sheet from the builder my rod clearances were .0018-.0019, mains were .0021, .0019, .0023, .0023 and .0023. with .009 end play. Does that all seem to jive or is idle pressure a little low?

What idle RPM? What oil filter? What weight oil? How hot was the engine? All things that can affect the answer to your question. Short answer, it's fine. lol

[bhill86]

Sorry, honestly with the rain hitting I didn’t pay much attention that time but the roads dried up so I just went for another short drive before I have to get ready for work. 15min drive or so, engine temp via mechanical gauge was 175-180°. Idle RPM via factory gauge is just above 750. Maybe 775 range. 10w30. 50° outside. And this time when I got back the mechanical gauge was reading a hair above 10psi. Maybe 12 or so. Filter is a wix.

Edit: I’ll add I was just over 50 lbs on the highway around 2800rpm. I’ll also add my factory gauge is and has read the same as it always has. The mechanical is a bit lower than what the factory gauge reads FWIW

[JSchmitz]

I would be nervous if it drops below 10 personally. But I still say you're good. As long as it jumps right up when you give it some gas.

[bhill86]

Since that can be subjective, I took a video just in case.

https://youtube.com/shorts/fFkDtODsFgw?feature=share

[lust4speed]

That no-name gauge could be reading low, and unless verified by a known good gauge it's nothing more than a reference point going forward. Say it normally reads 10 at idle and 40 at cruise -- if you one day see 25 at cruise, it's cause for concern.

Think Pontiac's idiot light was set to come on between 4 and 5 pounds so the engineers were happy with that idle pressure.

[bhill86]

That makes sense. This gauge is admittedly inexpensive. I know temp gauges can be tested. Can mechanical oil pressure gauges? Otherwise how would I verify any gauge to be correct?

[Schurkey]

Originally Posted by lust4speed

Pontiac's idiot light was set to come on between 4 and 5 pounds so the engineers were happy with that idle pressure.

Engineers? I'd have said the "Warranty Claims Department was happy..."

Originally Posted by bhill86

That makes sense. This gauge is admittedly inexpensive. I know temp gauges can be tested. Can mechanical oil pressure gauges? Otherwise how would I verify any gauge to be correct?

Like any other pressure gauges, it's not hard (kinda inconvenient, but not "hard") to compare one gauge to another by connecting them both to a Tee, so that a single pressure source can activate two or more gauges.

I test my compression tester gauges that way, and I'll be verifying fuel pressure gauges soon.

Compression testers connected to my shop air compressor via a brass tee and some quick-couplers. If the two gauges plus the gauge on the air compressor pressure regulator all agree within reason...I'm satisfied. (I have to turn off my ad-blocker to see the images.)
http://hbassociates.us/Compression_Tester_Tester_01.jpg



http://hbassociates.us/Compression_Tester_Tester_02.jpg



The "tee" might be the same, but the connections for the oil pressure gauge (or fuel pressure, in my case) would be different.

[bhill86]

I’ve got this mechanical “T’d” to the filter housing with the factory electric. Which, for what it’s worth reads the same now as it always has, albeit I little higher than this new mechanical. I guess I’ll either just have to monitor it for changes or get another gauge to compare to. Which, honestly, I don’t particularly want to do. But we’ll see.

[chuckies76ta]

Too me it's odd that it's dropping down so far when hot. What is the oil pressure like when cold and first start. What's of concern is that it has excellent pressure when you bring RPM's up. With your gauge plumbed at the oil filter housing, your monitoring the oil pump and bypass on oil filter housing. One thing I would really like you to do is remove your oil filter housing and check the bypass. It has a tiny screw that holes the spring and flat disc. I usually stretch this spring a bit to put a little more tension on the disc to hole it close. I'm curious if the spring tension on the disc is allowing it too open. Then the other issue could be the check ball in the oil pump, stuck open some allowing bypass oil. I'm think the oil pump. Engine sounds really good in video.