Core Plug Question

[Sherman Kaplan]

This is for a 73 Twin Cam engine.

I finished rebuilding my engine and also built an engine stand to test it on.  I was able to get it to run for about 30 seconds when I realized that the carbs that I thought were OK would need to be rebuilt.  They have been sent off to Joe Curto, who unfortunately has an 8 to 10 week backlog.   Besides the carbs, the only issue so far is that all 3 core plugs are weeping.   The machine shop supplied me with 1 5/8 for the two small plugs and 2" for the larger plug on the back of the engine.   From my research those seem to be the correct size. The core plugs are the cupped style.  I ordered new core plugs from RD Enterprises and they sent me 1 41/64 and 2 1/16.   I was able to get one of the 1 41/64 into the block, but the other one would not go in and I was afraid of using to much force (I am using a core plug setting tool).   I was able to find a new 1 5/8 plug locally, but it was a deep style plug, while the plugs that came of the engine are shallow style plugs.  I installed the deep plug, but now I am wondering if I should try and find a shallow 1 5/8 plug.  Is there any reason why the deep plug would not be considered correct?  The deep plug does sit a little proud of the block, while the shallow plug sits a little below the opening.   When fitting both plugs the tool face went flush to the block.  I'm trying not to be a DPO in the future

Also, when I installed the plugs the first time I used The Right Stuff.  The second time I used Permatex 2 (non hardening).  I did some research and it seems that there are a million different opinions as to what sealant to use.   Miles Wilkinson says to use Wellseal.  Loctite has a core plug sealant, but it is $125.00 for a bottle and they don't have a smaller size (I called Loctite for their advise).   Other possible choices I have come across are Permatex Indian Head Shellac, loctite 243, JB Weld.  Any thoughts?

Thanks,
Sherman

[BDA]

Pretty cool test stand! In case this interests you, When Dave Bean built my motor, he used freeze plugs that are screwed in. I have no experience with them other than mine haven't leaked. I would assume they can provide them. I've attached a picture.

[dakazman]

Damn Sherman, BDA said it all about the stand. . Sorry I don’t have the answer you want but just wanted to say that’s a test stand that the plans should be documented.
Nice garage BTW. Do I see a black lotus or burgundy? BLack I hope.
Dakazman

[Clifton]

Are they steel? I've heard second hand that they don't seal as well as brass ones. I have used brass with no sealant before I know. An auto machine shop guy said green loctite. I don't know what's the best.

[BDA]

Are they steel? I've heard second hand that they don't seal as well as brass ones. I have used brass with no sealant before I know. An auto machine shop guy said green loctite. I don't know what's the best.

If you're talking about my freeze plug, I assume the blue part is anodized aluminum.

[Sherman Kaplan]

Thanks for the kind words on the engine stand.  I bought some plans off ebay for a ford/chevy v8 and then modified them to fit the Twin Cam.  My welds are not pretty, but I think they are strong.  At least the engine has not fallen off the stand yet   I had a can of green paint so I decided to go with the green and yellow Lotus look.   

The plugs on the side of the engine are brass, the one in the back is steel.  That is what the machinist and RD supplied.  The deep core plug that I used is also brass.   Threaded core plugs would be great, but at this stage I don't think it would be feasible for me to do.  I think I would need a machine shop to do the work and supply the plugs.   When I spoke to the Loctite engineer she advised that green loctite would be too strong.   

I'm definitely an amateur at all of this.  It's a learning project.  My wife and I both recently retired so this keeps me busy and out of the house.   We moved from California to Colorado and I was able to build a nice shop to house my cars.

The Europa is Regency Red which is a burgundy color.   The paint is original, the car was last driven in 1980.  Unfortunately, it was stored in an unheated barn in Buffalo, NY.   The other cars in the picture are a blue 73 Triumph TR6 and a red 48 MG TC.  I also have an MGB, MG TF and an MGA.  I'm good at buying cars, but not selling.

[jbcollier]

 An you post a photo of the frost plugs in question?  I’m travelling and fon’t Have access to my archives.

Some plugs are the “cup” type and are installed with the open cup facing out.  The frost plug should be an interference fit and require considerable force to fit.  Do not hit in the center!  This “ shrinks” the cup and weakens the fit and seal.  Use a driver (sockets work well) that fits in the cup and applies force to the edges, not the center.  Use a sealant such as wellseal, shellac, aviation #2, etc.  They will all do the job.

The second style is dished but not “cupped”.  It should be a snug, hand fit into the block with the bulge facing out.  Again use sealer.  Fit the plug and use a substancial punch to “flatten” the bulge.  This expands the plug, securing it to the block.

The term “frost plug” is a misnomer.  It’s just a hole for the casting process.  If your coolant freezes, they may push out but probably the block will crack regardless.

[brucelotus26r]

In the engine I'm rebuilding I used a 2" on the rear and 2 1 5/8 on side. I pressed them in using my 20 ton shop press and Permatex Aviation Sealant. The rear plug was very tight I don't thing I could have gotten a 2 1/16 plug in? The side plugs seemed about right?
I haven't tried yet?? Hope it work's?

[Sherman Kaplan]

Attached are some pictures of the core plugs.  The plugs in the twin cam are the cupped style.  Factory is the shallow cupped style. Unfortunately, where I live the auto parts stores don't seem to keep a lot in stock and the only 1 5/8 was the deep cupped style so that is what I bought and installed. 

 I used a socket the first time, but after they leaked I bought a core plug setting tool (see attached picture) for the second install.  I don't think the deep core plug should make any difference or at best would give a little more seating area but I wanted to make sure.

The first picture is the 1 41/64 core plug
The second picture is the 1 5/8 deep core plug
The third picture is the setting tool.   

Thanks,
Sherman

[BDA]

It's always fun to get new toys!