|
|
Expert 5K+
Posts: 7393
   
Location: northern germany | Recently one of my core plug started to leak, untouched original 1960 383 (August 1959). It was the one behind the drivers side motor mount and even with the mount removed, there was no way to replace it safely the usual way with a hammer. For about 30 years I had original Mopar Performance cupped core plugs lying around waiting for this situation.
So I modified one to screw it in safely with the inside facing out, with a teflon bolt seal. It worked perfectly, does not leak a drop w/o sealant, and I was lucky I noticed that at the end of a long trip in my garage, as it looks like it was bad for some time (water never reached the floor) and it popped out scaringly easy!
While the issue is solved, I have one question! Are early big blocks any different than later years?
The machined seat was no way deep anough to install it the correct way, maybe 3/16" (didn't measure) and as you can see the MP plug protrudes installed the other way around (it is firmly seated). The sharp expanding sealing edge of the cupped plugs MUST be in the bore, not possible in my block installed the correct way.
Pictures and YT vids show the cupped plugs sitting deep in the block with even maybe 1/8" bore visible! The 1960 OE plugs are different and are flush with the outside.
Looks like I either have to find OE plugs or have to make all cupped washers the screw it type, which is probably a good idea anyway, yet that thing puzzles me. Does somebody know the answer?
Edited by 1960fury 2021-07-04 8:28 PM
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Funny thing, behind the "stalactites", the crud wiped away, the plug looked like new. I must add, I changed to a 16psi pressure cap, as recomended with that aluminum radiator some time ago.
Edited by 1960fury 2021-07-04 8:18 PM
 (core plug1ads1.png)
 (core plug1ds.jpg)
 (core plug2ds.jpg)
Attachments
----------------
 core plug1ads1.png (370KB - 107 downloads)
core plug1ds.jpg (61KB - 106 downloads)
core plug2ds.jpg (50KB - 104 downloads)
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | I forgot, if you run into the same problem and want to copy that, you MUST pull in the plug with a cupped solid washer, that only touches the periphery of the plug, otherwise the plug could expand before it is seated. The final sealing procedure is done with a smaller, flat washer, that pulls the center in (expands the edges).
Edited by 1960fury 2021-07-04 8:41 PM
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Did nobody ever replaced freeze plugs on an early big block? Look at that vid for instance, the plug bore that is showing AFTER the cupped waschers are installed is about the depth of my cars freeze plug seats! So the cupped washers can't work. Is that unique to my 383, or are all early big blocks like that?
https://www.youtube.com/watch?v=ZMWQrykG7qU&t=338s |
|
| |
|
Expert
Posts: 1740
 
Location: Alaska | many years ago I had a plug blow out on my 60 361. I replaced it with an original style cupped plug but don't remember the details, I think there was a machined lip inside for the plug to sit against.
That is the way the block is on my 354 hemi i rebuilt. |
|
| |
|
Elite Veteran
Posts: 827
Location: Northwest Iowa | If your motor had a shallow machined lip it was most likely supposed to have a convex disk type of a freeze plug,
not a cup style,
Edited by I GOT FINS 2021-07-05 1:05 PM
|
|
| |
|
Veteran
Posts: 298
Location: Kalispell, MT USA | My 64 361 used a cup style, smooth bore, no edge.
 (20180429_142718.jpg)
 (20180429_114929.jpg)
Attachments
----------------
20180429_142718.jpg (89KB - 102 downloads)
20180429_114929.jpg (74KB - 105 downloads)
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Rolland, the oe style is slightly cupped, more disc like and they are installed the other way around, so that they are flush with the outside, like the way I installed "incorrectly" the later cupped style.
Norm, you mean, just a straight bore, no "seat"? That would answer my question! |
|
| |
|
Location: North Australia | Sid, did you see this thread on my 1960 Imperial engine? The freeze plug blow-out problem scared me, and I made a similar design to the block plug solution offered by HHH.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=r...
Here is another thread. quality plug supplier info in the UK.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=r...
Another thread with a pictorial on installation of convex core plugs.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=r...
Does the plug you installed have a rubber 'element'?
Don't short cut this repair, it could have a bad ending.
Also the shallow machined holes for our engines do have a very slight lip in the base of the hole to assist holding the plugs. Maybe less than .005" shoulder.
Hope this helps Man.
Steve.
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Thanks Steve! Your version sure looks better than mine, but I was in a rush and didn't want an O-Ring or rubber seal of any kind. So the right term is "stepped bore" (even though I do believe the actual opening is not a bore, it seems as cast, with only the seat machined).
So can someone confirm that later BBs use a straight, non "stepped" bore? |
|
| |
|
Veteran
Posts: 298
Location: Kalispell, MT USA | At lease by 1964 it went to smooth machined bore. No step. I used a brass 383 block set I found on-line. Cup style plugs.
Norm |
|
| |
|
Extreme Veteran
Posts: 406
Location: Hilltown, PA | It's been many moons, so don't take this as gospel, but I think the early BB motors did use the flat style core plug.
With the flat style plug the bore is machined shallow, and has a lip or ridge not far into the bore for the core plug to rest against. You installed the plug convex side out, then struck it with the proper tool to force the plug flat, or slightly convex, forcing against both the lip and bore of the hole. Apparently they were easy to screw up - I never installed one, but I remember them being in the Dorman freeze plug box, and being told they were for "weird old Chrysler crap".
The cup style obviously requires a deeper un-stepped bore, and supposedly were easier to install and get a dependable seal.
At some point (probably during the Oldsmobile core sand debacle) we stopped using press in plugs altogether and used only marine brass expandable core plugs - unless obstructed by a motor mount or bracket.
Gregg
|
|
| |
|
Expert
Posts: 3775
Location: NorCal | 1960fury - 2021-07-05 4:31 PM
Rolland, the oe style is slightly cupped, more disc like
Commonly referred to as a Welch Plug. |
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Thanks gang, where else could I've gotten this information? Until now I always thought all BB are identical, other than casting#s and bore differences of course. That 70s thinwall thing is a myth I believe. I'm glad that the old BB have the stepped bore, so you can securely screw the plugs in and seal better that way (90° sealing edge). |
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | Looks like I received the answer already years ago,  that said the statement, that the cupped style does not work on early BBs is not correct.^
http://forwardlook.net/forums/forums/thread-view.asp?tid=52145&post...
Edited by 1960fury 2021-08-30 10:11 AM
|
|
| |
|
Expert
Posts: 1223
Location: Ramona, CA | Here are some pictures of the disc freeze plugs for my 1960 413. Included are the correct Melling numbers for the block and heads.
https://photos.app.goo.gl/cvt3DR9HTSU62cvd7
And another thread about them.
http://www.forwardlook.net/forums/forums/thread-view.asp?tid=72323
They are very hard to install in the car, especially the one behind the motor mount which is the one that failed on my car. I still have a rubber plug in mine until I pull the engine out.
 (melling1.jpg)
 (melling2.jpg)
Attachments
----------------
melling1.jpg (144KB - 76 downloads)
melling2.jpg (225KB - 78 downloads)
|
|
| |
|
Expert
Posts: 1223
Location: Ramona, CA | You can also get copper expansion plugs from Dorman but I found the new ones are junk and won't stay in. You have to get vintage USA made ones to work.
 (dorman1.jpg)
Attachments
----------------
dorman1.jpg (45KB - 71 downloads)
|
|
| |
|
Expert 5K+
Posts: 7393
Location: northern germany | NicksGarage - 2021-08-30 12:25 PM
You can also get copper expansion plugs from Dorman but I found the new ones are junk and won't stay in. You have to get vintage USA made ones to work.
But they sure look cool/50s. I'd use them with a bracket across/behind the bore, like I did with the MP ones. |
|
| |
"Freeze" (Core) plug question
