Technical freeze plug replacement on a gen 1 392 hemi. what's the trick?

what's the trick to replacing the core plugs on a gen1 392 hemi?

 

Don’t try to punch them in to remove them. There is a step in the casting that prevents that. Drill a hole in the center and slide hammer them out or pry from a larger hole.
Once removed, clean the block with a wire brush until clean/ rust free.
I like to use indian head/ aviation sealer in the block.
put the plugs in the holes with the convex side up. Use a hammer to hit the convex shape until the plug is distorted into the block. Don’t hit it more than needed to seat, you can go to far.

 

Ive also see guys take sheet metal screws into the freeze plug, use a pry bar and remove them that way.

 

I think I have some freeze plugs if ya want them.
Shipping is all they will cost you.
Give me there dimensions.

 

I had the shop bore out the step so I could use normal cup style plugs, fwiw.

 

There use to be aftermarket ones from Milodon and Donovan that were alum. with an oring and a bolt through the middle that held them in. That would be an option if the look didn't bother you. We ran those in dragster's years ago.

 

Thanks Trendz! Did you mean convex side out? Where can I buy Indian head sealer? I'm surprised they didn't have to change the name to Native American sealer to keep the woke crowd happy!

 

X2 what @TRENDZ recommended.
I had two leaking freeze plugs in my 354 Hemi.
First, remove the exhaust header/manifold. If the leaker is under the motor mount, remove that too.
Then, to remove the leakers, I drilled a small hole in each center, inserted a screwdriver, and pried it loose.
In the picture, you can see the "step" in the casting that he mentions.
After thoroughly cleaning, I just applied a *thin* layer of black RTV before pushing the new freeze plugs in, convex side out (so it's like a dome).

 

Not sure if this is the same product @TRENDZ is talking about.
I have used it for years & it always was called Indian head with a image of a Indian chief head on the bottle. Now same product is called ....

If you have the convex flat style plugs, be sure to install them with the bump outside .... When you install them and drive them in, the bump gets inverted & applies pressure holding the plug in place.
When you look at your old soft plugs the bump is inside to the block ....
The trick is to install them facing outside, when you smack em hard enough with a hammer the bump is now inside & pressure holding it in is applied. ....... Ask me how I know

 

Once you get them out, just buy the o ring style aluminum ones from Hotheads that are retained like a block heater. I've had the originals pop out twice when I'd get on it and pressure would build up in the cooling system. Not a good situation. Once you get them make sure you are getting a good fit and seal on the original hole in the block as I found out they may need to be resized on the lathe to allow the o ring to fit tight against the block in the hole. We found this out on the dyno...messy.

 

After blowing out two regular freeze plugs in the hemi in my dirt modified, I also replaced them with "bolt-in" style (it was so long ago, I don't remember where I got them).

No problems since.

 

Ok, one more time. They are NOT FREEZE PLUGS! You can call a pig a duck, but you will go to your grave waiting to hear one quack!

They are core plugs for removing the sand from the block casting process.

They have no value whatsoever in protecting the block from freezing*. That is what antifreeze is for. You do not need to attempt to "preserve that function" as that is not what they do. Bolt something in. There is no downside to doing that.

I have my machinist bore the holes for cup plugs. Those don't fall out. On race engines I have him tap for pipe plugs, which get torqued, with 271 red Loctite.

Those, of course, each require that the block be at the machine shop.

Otherwise, use these: https://hothemiheads.com/main_caps/freeze_plugs_stainless.html

*I am from Southern New England, and made a tidy sum every spring replacing blocks and heads for boat owners that did not winterize their boats. I have seen whole block sides split from front to bell, through the core plug holes, with the plugs still wedged into one, or the other split side. I have seen blocks with an oil pan rail blown completely off of the bottom, with the plugs still in, and all manner of head damage.

 

Indian head cement. I didn't think anybody else knew about this stuff. Fantastic stuff, just don't get it on your fingers!!!

 

I use Hot Heads bolt in stainless ones....I also had a core plug blow out....

 

When I put the new convex ones in I use 2 large ball peen hammers smacked head to head to put that dimple in the convex plug.

 

After having 3 core plugs pop out I tried replacing them with stock type plugs using in weld and still had problems keeping them on dads 392. From here out I will only use bolt in plugs like Hot Heads Racing sells in early Hemis.

 

Correct name for the plug is "expansion plug" as it expands when you wack it with your hammer (s) as OJ suggested. I like that two hammer thing.

Soft plug and core plug also work depending on what region you are in. They never were intended to pop out and save a block as all too many will tell you and experience says even if they get pushed out the ice often times still cracks the block.

I've always used #2 {Permatex on them but that is what I was taught to use. Indian Head is a great sealer for a lot of things though and should work fine.

 

I use KD block sealer on them

 

Colloquialism. It's common in America. Everyone understands what you are talking about. Most folks call all copy machines "Xerox machines".

 

Except that they don't. I live and work in greater Silicon Valley, not far North of Xerox PARC (Palo Alto Research Center).

The term is now copy machine. I have not heard anyone use the term Xerox machine in about two-decades, maybe more.

Repeating something until it becomes commonplace works for lies, too. It does not elevate them to the truth.

 

But "Xerox Machine" is traditional. This forum is not concerned with what's happened in the last "two decades, maybe more".

 

zing

 

Who in the world cares !
Just let it go !

Tommy

 

With all do respect Tommy, it is one of those things that bugs me. To me when people perpetuate myths it undermines the truth. By using proper terminology it helps dispel those myths.
So in answer to your question, I care.

 

Soft plugs.....

 

put mechanical plugs back in and save yourself a headache later

 

Well Lane ,
I’m just trying to keep everyone in a pleasant mood .
When in the past 70 years ,,,,,the buying public has continuously read articles,,,,and sales ads,,,,,that called them freeze plugs,,,,why should we condemn anyone for using the term .
I know they are core plugs,,,,but I’m not going to get bent out of shape by the terminology.
Life is too short,,,,,,let’s just laugh and go on .

The same goes for harmonic balancer,,,,,,,I understand the real principle .
But how can anyone condemn someone for using the term,,,,,,when it is called exactly that in a GM Mr Goodwrench website selling the parts ?

People come here to enjoy cars and car related talk .
And many,,,,,myself included,,,,,,don’t know all the correct terminology for all the thousands of components that were produced in the last 100 years .
Let’s just try to welcome people in and maybe ,,,,just maybe,,,,,we can all become friends.

I know it is good to call parts by the correct term,,,,but,,,,,,who’s to say what is the correct term ?
When ,,,in many times in the past,,,,,core plugs had been pushed out when a block had frozen and saved the engine !
I know the plugs are not there for that per se,,,,,but if it works,,,,who cares ?

Tommy

 

May be the automotive instructor in me! I’m picky on terminology! Your right though in the end it doesn’t really matter.

 

I blew one of the new ones out of my 331 Hemi in my '33 Plymouth. I was at the circle track races so I had my daughter in law pick me up a rubber bolt in one at the parts store so I could drive it home that night. I now carry a spare bolt in plug in the trunk.

Dave

 

I’ve used the Hot Heads’ plugs on both of my 392’s with good success. A well known builder, since deceased, refused to use the the ones I provided, saying the originals were best. Two, however, failed on the test stand during breakin and I replaced them all with the Hot Heads plugs. They have been good now for 15 years.