Discrepancies in information on LA and Magnum series oil gallery plugs

[Kern Dog]

If you really want to see how bad this is, put your plate on and tighten it up.

Take a .001 feeler gauge and try and slip it between the block and the plate.

That will tell you how flat (or not) the block/plate are.

I see your point but did you see the channel in the thrust plate?

The plate from the 318 that also had no plugs:

See, the second plate appears to fully block off the flow rendering the plugs to be redundant. The first plate has that open space that surely allowed oil to flow under the plate and down the front of the block.
Again, I’m not claiming to know it all here, I’m trying to make sense of it.
Here is a closer look:

 

[junkyardhero]

Could be that Mopar discovered that there was enough airborne oil to sufficiently lubricate the chain but didn’t think it was cost efficient to change production ?

all they cared about was it getting out of the warranty period in one piece.

if they found out they could save 1/5th of cent by eliminating the plugs and it had no detrimental effect on warranty claims then they would absolutely eliminate them.

 

[RustyRatRod]

If you really want to see how bad this is, put your plate on and tighten it up.

Take a .001 feeler gauge and try and slip it between the block and the plate.

That will tell you how flat (or not) the block/plate are.

My only argument here is that it can be done either way.......just like Chrysler did. I'd prefer blocking the gallies off with plugs on the LA and maybe drilling a small hole through the plug and plate for timing chain oiling. You could do the same with the Magnum. Just block the gallies off with plugs and use the LA plate and drill the hole in one of the plugs and a corresponding hole in the plate. In my mind, that's better oil control then the huge space in the plate that Chrysler made. I'd much prefer to divert more oil elsewhere in the engine like the crank for instance. You're missing the boat thinking I'm arguing against leaving it alone. I'm not. I'm simply saying you can do it another way. There's enough evidence in this thread already that shows the engines came both with and without the plugs......at least for the LA. I've pulled original engines myself and found plugs there. There's always more than one way to do things.

 

[Newbomb Turk]

I see your point but did you see the channel in the thrust plate?

View attachment 1716402883

The plate from the 318 that also had no plugs:

View attachment 1716402884

See, the second plate appears to fully block off the flow rendering the plugs to be redundant. The first plate has that open space that surely allowed oil to flow under the plate and down the front of the block.
Again, I’m not claiming to know it all here, I’m trying to make sense of it.
Here is a closer look:

View attachment 1716402885

I don’t know when they started using the plate with the relief in it.

My best WAG is Chrysler was trying to get more oil to the timing cover area so they put that relief in there. The bolt with the hole in it (if it came with one because some engines came with them and some didn’t and my dad told me in 1980 when we took mine apart and it had the bolt that some didn’t have the bolt and if you wanted one you could run to he dealer and buy one…and IIRC he said it was 30 cents or something…of course that would have been in the 1966-1977 time frame), and the drip tray were IMO efforts to get more oil on not only the timing set but on the fuel pump arm and eccentric.

I’ve seen many pump arms and eccentrics that were are up and Thats only from lack of oil.

One more thing on the bolt. I’ve seen the bolts get clogged with crapola that finds its way into the low spot thats supposed to feed it.

I always use 2 part epoxy or JB Weld and fill that low spot in so oil and trash can’t get caught and pile up in there. I also fill in the drain holes that put oil back on the middle of the crank. If I remember tomorrow I’ll take a couple of pictures of that and post them in this thread.

Clearly, if you have the plate with the relief and you out the plug in the gallery you’ve defeated the purpose of the relief.

If you try and make sense out of what Chrysler was doing back then you’ll end up in a rubber room lol. I gave up trying to figure them out long ago.

Just because I’m curious, are you using solid or hydraulic lifters?

 

[Kern Dog]

My 360 is a 1990 mill that came with the hydraulic roller setup. I'm sticking with that.

 

[Ted265]

I do have the plugs in the core plug kit.
How about knocking the plugs in but drilling a small hole in the one behind the diverter….?

Put the plugs in, drill a small hole in one of them first, then drill a big hole in the plate so it squirts oil on the sprocket & chain instead of the back of the plate.
I drilled 0.5mm holes in both plugs - one aimed at the fuel pump eccentric and the other at the chain. You can use a punch to set the angle of the hole in the plug if you want to aim it at a particular area

 

[TF360]

I would put the plugs in and use a standard thrust plate ( like your 318 plate.) Pick up a factory bolt with the hole in it for oiling. All bases covered. You could even add the little drip plate to have oil drip on the chain. It seems that Chrysler wanted a little drip in that area. If the plugs help divert oil up toward the lifters, that a good thing.

 

[Alfajim]

I get it, but you won’t lose oil pressure if you leave them out. It’s not like leaving out a 3/8 pipe plug.

Yep it seems that ya all are walking right past the one simple fact! The right passenger side lifter gallery is is drilled either from the front or the rear depending on the tooling used at the factory. Then the R/H gallery is threaded for a 3/8 pipe plug in the front of the gallery behind the dist. drive so the front hole is NOT pressure fed it is used to allow access for the allen pipe with the correct allen tool! So the plug in the front is never pressure fed and useless if installed . The left side galley drivers side is drilled all the way through so oil pressure is there all the time. The thrust plate with the slot is to lube the timing chain on stock engines using the link belt type chain as they are a high wear item as roller chains are less wear prone the sprockets wear most and the pins some which allows for chain stretch which then wears the sprockets even more. Also the holed drilled in the upper left side bolt is a joke as the only oil that can come out is what is thrown off the dist. drive so totally useless. The only oil supply to allow for lubing the chain is the drivers side galley.!


Jim O

 

[NC Engine Builder]

Yep it seems that ya all are walking right past the one simple fact! The right passenger side lifter gallery is is drilled either from the front or the rear depending on the tooling used at the factory. Then the R/H gallery is threaded for a 3/8 pipe plug in the front of the gallery behind the dist. drive so the front hole is NOT pressure fed it is used to allow access for the allen pipe with the correct allen tool! So the plug in the front is never pressure fed and useless if installed . The left side galley drivers side is drilled all the way through so oil pressure is there all the time. The thrust plate with the slot is to lube the timing chain on stock engines using the link belt type chain as they are a high wear item as roller chains are less wear prone the sprockets wear most and the pins some which allows for chain stretch which then wears the sprockets even more. Also the holed drilled in the upper left side bolt is a joke as the only oil that can come out is what is thrown off the dist. drive so totally useless. The only oil supply to allow for lubing the chain is the drivers side galley.!


Jim O

Unfortunately you are dead wrong. The driver side galley is indeed pressure fed, that's what supplies oil pressure to the lifters. And that threaded plug goes in from the rear, not the front.

 

[Alfajim]

Unfortunately you are dead wrong. The driver side galley is indeed pressure fed, that's what supplies oil pressure to the lifters. And that threaded plug goes in from the rear, not the front.

Sorry wrong end of the engine was thinking it was front dist. location like B/RB not small block like Chevys. Looking at the pictures it appears Chrysler used a sealer on the thrust plate to block something like permatex #1 paste to seal the plate. So using the plugs in the front galleys is the safest method and do as recomended about drill a hole in plug and use the factory slotted plate to lube the chain. The drilled bolt still only feeds oil by any leftover from the lifter chamber by splash collection.

 

[Kern Dog]

Yeah, NC...I appreciate when people try to help but incorrect information helps nobody.

 

[sedbld]

I’m also going through the same process and have been wondering the same things as Kern Dog. I have a 70 340 that I’m going through that was “rebuilt” and ready to run when I bought the car. But since I have been working for ma Mopar as a dealer tech since 87 I don’t trust many “rebuilt” items. It’s been 10 years or so since I have rebuilt an LA engine and have forgotten more than I will ever remember. During disassembly I find that the timing marks are lined up incorrectly so I know that was not “rebuilt” correctly. Then I remove 4 valve cover bolts from the thrust plate and find one that matches Kern Dogs 360 style with a drip notch on the back drivers side of the plate. No drip tab and no oil galley plugs behind the thrust plate. So then I start looking and find many people say yes to installing the plugs and many say no to the plugs. And the same goes for drilling small holes, the factory drilled bolt and the drip tab. It seems that this is a definite rabbit hole with no clear path or explanation of what to do. Digging through some very old Mopar Performance books and service manuals I come across these pics and explanation but only very few words And it’s for a 3.9 build in the MP engines book. I also dig through and find some NOS MP parts for LA’s that I bought back in the late eighties when I had a 360 Aspen R/T (lol) when I first started for ma Mopar. I found a thrust plate that is exactly like Kern Dogs 360 and a LA engine small parts kit with core plugs and such and inside that unopened package is 3 oil line plugs as the paper says. I also have a 318 short block that I have had since the late 90’s and it’s never been apart and it has the plugs in it. Like I said I have been working on these things for a long time and have forgotten a lot but I’m pretty sure IIRC most LA’s had the plugs so I am going to go with that route and use the plugs and the drip tab (which is still available through vintage parts ) and let’r ride. Just my two cents but every mechanic has their own way of doing things

 

[Newbomb Turk]

I’m also going through the same process and have been wondering the same things as Kern Dog. I have a 70 340 that I’m going through that was “rebuilt” and ready to run when I bought the car. But since I have been working for ma Mopar as a dealer tech since 87 I don’t trust many “rebuilt” items. It’s been 10 years or so since I have rebuilt an LA engine and have forgotten more than I will ever remember. During disassembly I find that the timing marks are lined up incorrectly so I know that was not “rebuilt” correctly. Then I remove 4 valve cover bolts from the thrust plate and find one that matches Kern Dogs 360 style with a drip notch on the back drivers side of the plate. No drip tab and no oil galley plugs behind the thrust plate. So then I start looking and find many people say yes to installing the plugs and many say no to the plugs. And the same goes for drilling small holes, the factory drilled bolt and the drip tab. It seems that this is a definite rabbit hole with no clear path or explanation of what to do. Digging through some very old Mopar Performance books and service manuals I come across these pics and explanation but only very few words And it’s for a 3.9 build in the MP engines book. I also dig through and find some NOS MP parts for LA’s that I bought back in the late eighties when I had a 360 Aspen R/T (lol) when I first started for ma Mopar. I found a thrust plate that is exactly like Kern Dogs 360 and a LA engine small parts kit with core plugs and such and inside that unopened package is 3 oil line plugs as the paper says. I also have a 318 short block that I have had since the late 90’s and it’s never been apart and it has the plugs in it. Like I said I have been working on these things for a long time and have forgotten a lot but I’m pretty sure IIRC most LA’s had the plugs so I am going to go with that route and use the plugs and the drip tab (which is still available through vintage parts ) and let’r ride. Just my two cents but every mechanic has their own way of doing things

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So the question is this. If those plugs are absolutely REQUIRED, how does the cam plate with the relief work with the plugs?

Answer: it doesnt.


Question: if I don’t use the plugs and use the plate with the relief, what happens to my oil pressure?

Answer: NOT A THING. How many engines did Chrysler ship with that plate? Who knows but it wasn’t 10 or 20. I’d suggest it was in the hundreds of thousands. At least.

Question: How many of the hundreds of thousands of engines equipped with the cam plate WITH the relief had bearing issues above the normal rate?

Answer: NONE. I’ve never seen a bearing issue traced back to low oil pressure, low oil volume because that plate with the relief was used. And if anyone here has any PROOF that it was an issue, post it here.

I say it did not happen because those plugs don’t do ****.

It’s not a rabbit hole. It’s 45 years of working on this junk that says Chrysler sent out probably MILLIONS of engines without the plugs and there isn’t a single tech bulletin, not a single WORD in any Chrysler literature I’ve seen saying if you do NOT install those plugs your engine will **** the bed.

That’s all because it doesn’t matter.

If you are a nervous Nellie, who thinks that two cup plugs will make or break your build, then by all means, put them in.

If you can think outside the bun, look at the facts and the HISTORY of the small block engine then leave them out.

If your engine has low oil pressure it won’t be because you left a dollars worth of cup plugs out.

 

[Kern Dog]

As brutal and abrasive as the above post was, I have to give credit.....it makes plenty of sense to me.

 

[Newbomb Turk]

As brutal and abrasive as the above post was, I have to give credit.....it makes plenty of sense to me.

I’m not opposed to installing the plugs. It makes no difference to me.

What boils my hide is the nonsense that gets bantered around about using the plugs.

I do lots of stuff when I build an engine that I can’t prove that it does a thing. I do it because it makes ME feel better having done it.

It’s the same way with the plugs. If it makes the end user feel better by all means use them. It won’t hurt the engine.

I still suggest if you use the plugs, drill a hole in the cup plug and a small hole in the cam plate to get full pressure oil out to the timing set. IMO that is a MUST do, with or without the plugs.

Edit: just for clarity I was forced into catholic education until half way through my sophomore year.

The Q&A format is a remnant of the education. Catechism is how they teach. That’s what that was lol.

 

[sedbld]

I have to agree it all makes sense to install or not to install. I just wanted to put out the information that I had found. But again everyone who wrenches does things their own way. If we all did it the same it would be a boring world IMHO

 

[Alfajim]

Just wanted to add a thought here about plugs or no plugs. I think on a stock engine running stock oil pressure c45# it is not enough pressure on the back side of the plate at the hole just 14 psi. If you are running a race engine with 90=100 psi oil pressure thats 28 psi or more on that area of the plate so using the plugs in that circumstance adds a measure of safety so the pressure won't lift the plate. I will include a real world example. Years ago in the 70's when my Dad and I had our shop in Salt Lake our primary cars worked on was Jaguars, a E type cam in with the oil filter can blown back over the hols down bolt, the bolt had a washer head about 3/4" in dia. the can was cone shaped on the bolt end and the can was folded back over the bolt about 1/2"??? WOW. Never having seen this before WTF, so took apart got another can and put back together to start and see what's up refilled the pan E types held 10 quarts in those days started engine bam big noise and 9 quarts of il on floor before I could get the key off, umm-WTF again. unbeknownst to us was the oil pressure relief valve was stuck. the E type use a peculiar pintle type valve it was three fluted in the bore and used a taper to seal on closed. Took filter housing off found the stuck valve it had worn off kiter. Replace the housing and another can and oil pressure sender refilled started all good. I asked an engineer friend who knew about these things and he said it would take north of 1000 psi to push that tapered can that way as there was no flat surface to push against. Have worked on a lot of aircraft over the years with HIGH PRESSURE hydraulics FA-18 uses two high pressure systems one is 3000psi and the other is 5000psi you have no idea of the damage done with a leak, the use only stainless tubing no hoses ever and B nut connections are really peculiar.

 

[Kendog 170]

I do have the plugs in the core plug kit.
How about knocking the plugs in but drilling a small hole in the one behind the diverter….?

That is what I'd do. My plate was nice and smooth with no reliefs and my plug kit did not have them. If it did, I would have installed them. It seems to me Chrysler was using some idea's on how to give the chain some extra oil on top. JMO Good luck with your build.

 

[66 Sat]

I agree with Kern Dog that it's as clear as mud. How can it not be when you have:

• Experienced engine builders saying you must use them
• Experienced engine builders saying you don't need to
• Books that say you should use them
• A design that changes randomly including: plugs, no plugs but a solid thrust plate, no plugs and a relief in the thrust plate, no plugs and a hollow bolt
• A design that doesn't seem to make sense e.g. why have plugs if the thrust plate then blocks off the hole?

Another experience with an older 318 (poly):
No plugs.
No oil pressure issues.

 

[NC Engine Builder]

The holes are there because the factory drilled the holes 1/2 way from the back, and 1/2 way from the front.

 

[Kern Dog]

That isn't the point of confusion, man.
The point that isn't clear is how there was no consistent standard practice. There are too many variables and no consensus. My 68 standard bore, standard steel head gasket 318 had no plugs but had a plate that did not have a relief groove in it. It clearly blocked oil flow. It had 4 matching screws retaining the plate, 4 tapped holes in the face of the block and none of them had a hole drilled through them. Stock link type single row timing chain. The engine looked worn out but was as original/factory assembled as any that I've ever seen. I've torn down a few 273s that looked the same. My own 1990 360 had no plugs but had that thrust plate with the relief groove in it. The MP crate 360 we tore down 3 months ago had no plugs in it but had the same thrust plate as my 360.
There has been no consistency from the engines that I have seen except that none have had the plugs in them.
I'm not claiming that none ever did, just that I have yet to see them. Others seem to have never seen an engine that did NOT have them.
This is where the clear as mud statement applies.
In theory, it would seem redundant and pointless to have the plugs in place if the thrust plate looked like this:

Seriously, do you see oil getting past this?

 

[Desoto291hemi]

I agree with you,,,but in automotive manufacturing,,,you do as the engineer tells you .
If they say to put in plugs,,,,that’s what it gets .

And it depends on who the engineer is and at what time .
Managers change and with them ,,,(many times),,,,the procedures .

Tommy

 

[Kern Dog]

Engineers….

In years of construction, I’ve seen “solutions” from engineers that make no sense and are impossible to implement. That is not to say that engineers are idiots, just that they are quite capable of mistakes that they refuse to acknowledge due to their education.
An engineer would probably state that the plugs and thrust plate with dead ends are necessary despite common sense telling you otherwise.
An engineer that had actual hands on experience is a rare and great asset. An engineer with clean, soft hands with zero real world experience is a variable that often comes up with Impractical and impossible ideas.

 

[408 swinger]

So, I was thinking. I went back to the beginning of your post. The second pic is from the Magnum engine, yes? "Knowing" how manufacturing works, the 3.9 Magnum V6 came with a timing chain tensioner. Now here's where I put too much thought into it. That void would allow oil to spill onto the chain. Reason they did it on the left side is the chain would pull it around and up the other side onto the tensioner slide. If they did it on the right side, the chain would pull it AWAY from the actual tension side. So, if the made this special for the V6, why make two different versions. Just use the 6 on the 8. Idfk.....

 

[Kern Dog]

So, I was thinking. I went back to the beginning of your post. The second pic is from the Magnum engine, yes? "Knowing" how manufacturing works, the 3.9 Magnum V6 came with a timing chain tensioner. Now here's where I put too much thought into it. That void would allow oil to spill onto the chain. Reason they did it on the left side is the chain would pull it around and up the other side onto the tensioner slide. If they did it on the right side, the chain would pull it AWAY from the actual tension side. So, if the made this special for the V6, why make two different versions. Just use the 6 on the 8. Idfk.....

All of the pictures in post #1 are with a 1968 318 as shown here:

I think that there are 2 pictures with a thrust plate from my 1990 360 in the foreground but the '68 318 is behind it. You can see above that the crank sprocket is the single row, stock design. 4 screws/bolts holding the plate in place with no drip tab. This engine was from a car and used in a truck so it has a rear sump pan painted blue along with the valve covers.