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Welsh Plugs
https://www.ausmini.com/forums/viewtopic.php?f=2&t=37521		 Page 1 of 2
Author:  Rodney [ Thu Nov 08, 2007 12:27 pm ]
Post subject:  Welsh Plugs
Ok kids,

When you have never done this particular job on a mini, I have a few questions.

1. Are they welsh plugs, welch plugs or core plugs???

2. There's three across the block front and one at the side - correct??? (I always thought there were 5 in a mini)

3. When putting them in, is Loctite 243 a good enough sealant.

Cheers all
Author:  Curly [ Thu Nov 08, 2007 3:23 pm ]
Post subject: 
1. Welch or core plugs - same thing
2. Three plus one = four.
3. Make sure all surfaces are spotless (no paint, rust or scale) and use a sealer sparingly. 243 is a thread locker, use a non-silicon gasket cement or thread sealer. Your GMH dealer will sell you a small tin called 'Holden Sealing Compound #3835215 which works a treat on most applications like this.
Author:  Wombat [ Thu Nov 08, 2007 3:57 pm ]
Post subject: 
1275 has 5 plugs - small bore has 4
Author:  Mike_Byron [ Thu Nov 08, 2007 5:21 pm ]
Post subject: 
Wot they all said but there is more.

To get the old ones out you get a medium drift and a hammer and simply place the drift at about 3.00 and tap it with a hammer. The plug should start to turn in the plug hole. Grab it with a pair of multi grips and pull it out.

Pay particular attention to cleaniless around the plug hole. Make it real clean.

You will find the flat surface of the new plug has a convex shape - note that.

Push and very lightly tap the plug into position in the plug hole until the outer ring edge is flush with the block.

Then get the drift you used to remove the old plug. Put the drift dead centre on the convex part of the flat surface and give it a sharp tap with a hammer - it should go slightly concave. This spreads the load across the plug hole and locks the plug in place.

Loctites and the like are a good idea but they wern't available when these engines were being built. It was done as i just described.

Mike
Author:  Curly [ Thu Nov 08, 2007 6:03 pm ]
Post subject: 
Wombat wrote:
1275 has 5 plugs - small bore has 4


Maybe the A+ 1275 engines had 5 (2 smaller ones on the side I think), but I'm pretty sure that my Cooper S engines only have 4.

There's also a different design of plug between the small blocks and big block. The small blocks have discs, the big blocks are cup-shaped. Mike's advice is spot on, they never used sealers originally, but back then the holes hadn't been in service for 40 years :wink: .
Author:  matt van'74 [ Thu Nov 08, 2007 6:06 pm ]
Post subject: 
Stag is a good sealant i find.

Matt
Author:  Smokie [ Thu Nov 08, 2007 9:13 pm ]
Post subject: 
And they can pop out at the worse possible time...... :?
Author:  Morris 1100 [ Thu Nov 08, 2007 9:39 pm ]
Post subject: 
One way to stop the silly flat ones from blowing out is to fit retaining screws to keep them in.
You drill and tap a small hole into the block on each side of the plug and use a screw and washer overlapping the plug to keep it in. You can even fit a strap across the plug for more strength . :wink:
Author:  drmini in aust [ Thu Nov 08, 2007 9:41 pm ]
Post subject: 
1100S etc and later 1275 ones have 5, the S had 4.

The cup ones are easier to fit, I select a socket that just fits inside the rim and tap them in with BFH.
As said clean the opening out well, and Stag is the best sealer ever invented. 8)
Author:  sports850 [ Thu Nov 08, 2007 9:42 pm ]
Post subject: 
Isn't the (partial) idea of them to give somewhere for excess pressure to escape by popping the plug instead of cracking the head in extreme conditions or is that just a myth ?
Author:  matt van'74 [ Thu Nov 08, 2007 9:45 pm ]
Post subject: 
sports850 wrote:
Isn't the (partial) idea of them to give somewhere for excess pressure to escape by popping the plug instead of cracking the head in extreme conditions or is that just a myth ?


I have heard that in the event that the water or coolant were to freeze the welsh plugs are the weakest point so these are forced out thus preventing damage to the head block etc etc. Not sure how true this is though. Can anyone verify this?

Matt
Author:  sports850 [ Thu Nov 08, 2007 9:47 pm ]
Post subject: 
I know they are a by product of the casting process as well but I've heard them explained like that . Anyone ???
Author:  drmini in aust [ Thu Nov 08, 2007 9:50 pm ]
Post subject: 
The real reason for these holes was to get the sand out after casting. :wink:
Author:  sports850 [ Thu Nov 08, 2007 9:58 pm ]
Post subject: 
Yeah but wasn't there an ulterior motive to using a pressed in plug rather than something more substantial or was the "prevent cracking" an excuse to cover using a cheaper pressed in plug instead of a more expensive threaded pulg or something . I'm talking engines in general , not just mini ones .
Author:  drmini in aust [ Thu Nov 08, 2007 10:04 pm ]
Post subject: 
The Yanks call them freeze plugs because if you freeze the water in the block, the expansion pushed the plugs out. Dunno if it saves the block from cracking though.
I remember Mitsubishi had some problems with the early Astron blocks cracking near the welch plugs, but it was a design fault.
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