Hot Rods SBC external oil gallery plugs without hex

Hi folks,

I've just purchased two 3970010 blocks, and I've run into an issue with the external oil gallery plugs. They're flat, with no drive socket. In fluid power, it's very common for a cross drilling to have been sealed using a break-off plug. It's essentially an external hex with a thread on both ends. As you thread the plug in, you simply keep applying torque until the thread breaks away from the hex. You then turn it around and do the same in another hole. The end result is a plugged hole with a flat surface (no hex or square socket). All these plugs I've encountered come pre-coated with a thread locking compound. The best way to remove these is to heat them (to cause the locking compound to break down) then drill them and use an extractor. I've already tried this approach on two plugs on one of my 3970010 blocks, with no luck so far. I can't guarantee these plugs are even threaded, but that's the assumption I'm working with now.

If anyone has experience removing these plugs on an SBC, I would love to hear your thoughts, or at least confirm they are indeed threaded (as opposed to an interference fit). Both blocks were manufactured in Canada in 1973, which makes me think this style of plug is unique to that plant. I can't find any real info on this anywhere else. I've attached a couple of pictures of the plugs for reference.

Update: I've found some info that leads me to believe these are not threaded, but are an interference fit. That makes sense, they don't look like they have a thread on them.

 

Center drill them & use an easy out ??

 

Always thought those were pressed and not intended to be removable.

 

I've tried that, it's not working.

 

I found one article that says there are plugs that are installed at the foundry as the block is still hot. They probably are intended to be left in, but I'm not comfortable doing that. I think I'm going to try heat and a slide hammer. The article mentions they use wax as part of the removal process. Any idea how that works?

 

Not sure about your pressed in plugs, but for stuck bolts and studs it's common to heat the area up and melt wax to seep into the threads.

 

I was thinking it was something like that. I'm going to try this, though I can't imagine it would be too effective, considering it's an interference fit.

 

Waste of time unless you are having the block media blasted or shot blasted. If you have the block boiled out and go through all of the oil passeges with brushes all will be fine. Otherwise drill the plug and tap the hole for 1/8 inch pipe if it makes you feel better.

 

While I'm not a professional on the subject, I've never seen them removed, and i stop by the machine shop just about every day. He's been there about 40 years. Should i show him this or keep it a secret that he's been doing it wrong?

 

I have been working on and building small blocks for almost 60 years and have never seen a good reason to drill them out.I have a feeling they are part of the casting where during design they needed access.but when doing final casting the mold was modified with plugs (wood) if you have seen molds used in casting you know what I mean they use aluminium also.

 

I have never heard of this either, while my knowledge of SBC is not infinite this is a new one on me. Maybe in his part of the world (we don't have a location, 1st timer) they take those plugs out.
Good Luck NoxAstrum

Pat

 

I too think that it's not necessary. But if you must, drill them out and tap the holes for screw in plugs. Good luck. Lippy

 

I'm with 54 Vicky. To me it looks as though it's not a pressed in plug but simply an outline of a blocked off plug in the casting. Makes sense that they would plug the mold if they didn't want an open hole in the casting rather than go to all the extra labor steps of pressing a plug into each new casting.

 

I finally got two of them out. They are in fact solid interference plugs. I drilled them out (5/16") and tapped them (3/8-16). Then I heated them with propane, used compressed air to cool the plug (I'm not sure if this had much effect) and threaded a bolt in. It took me about three heat cycles per plug, but they finally came out with a slide hammer.

I understand most people don't feel it's necessary to take them out, but I couldn't sleep if I didn't. I rebuild hydraulic pumps and motors for a living, and it's standard practice to remove all plugs. We've had catastrophic failures in the past because contaminants were hiding behind plugs that weren't removed and inspected.

Also, I'm in Canada, both these blocks were made in St. Catharines.

 

You're welcome to show him, I doubt he'd be interested though.

 

Good going , may have been futile, but now you know !

 

Thanks! I don't consider it futile though, because you're right, I learned something and now I feel better about having full access to the galleries.

 

I admire your perseverance, but just out of curiosity did you find any sludge or debris behind them?

 

Not loose debris, though the gallery is quite rusty/flaky. I have lots of peanut shells and seeds to get out of the water jackets though, I think a mouse had a party in them.

 

you can sleep better now that you reinvented the wheel.

 

I'm sorry you disagree with what I've done. Re-inventing the wheel implies a waste of time or effort. This is neither, it allows me to ensure a higher quality result, and I've learned something. Curiosity and thoroughness are virtues, not vices. I came here looking for knowledge, on how to remove the plugs, not opinions on whether I should or not. Maybe in the future you could keep your negative comments to yourself. Thanks to everyone who tried to help.

 

Dude, you have 10 posts, 9 on this page. As a rule (more of a guideline) we usually require at least triple digits before bitch slapping a guy that has been on here for 10 years. Besides, he is Canadian and it is a well known fact there are no negative people North of the border...during summer. Nice work on the plugs though.

 

thanks billy I am sure if we went to an astronomy site we would find post by him on holding back the sunrise until he is fully awake

 

CAUSTIC !!............s'why I enjoy the HAMB so much!!
If your skin ain't thick...watch what you post!
6sally6
PS........I am glad you got the plugs out.....

 

I'm guessing the OP is a young person , armed with his superior knowledge he is here to show us how uninformed we all are . As he matures , he'll probably figure out how much he doesn't know , just like the rest of us......

 

I totally agree

 

Actually the guy asked a good question that no one on here was able to give a "for sure" response to.
I don't care if its his first post, if someone smarts off to him, he has every right to respond. I think he did the right thing. While its possible that removing the plugs provides no real benefit, I'd rather see someone do the best job he can when building an engine than simply ignoring it.
What I have found over the years is that ezy outs often break before a rusted plug comes loose and then you have to deal with trying to get the ezy out pieces out also. When plugs are onery, its either heat and then weld something to it, or drill it out and tap it oversize. In your case I would consider drilling it completely out and tapping to the next larger size OR drilling it undersize so you may be able to clean without complete removal....then tapping to that smaller size. I would be a little concerned that using a puller could crack the block. I don't know how hard you are smacking the puller but it seems they are difficult at best.
And you know what.......even all of us old grouchy farts learned something because he asked that question. Heck, I didn't even know they made plugs that break off intentionally......till today.

 

you completely missed the point reread and then you may comprehend he removed something that did not need removing as they were not plugs but part of the casting.back to your cadillac as you have no concept of what needs to be removed when building an engine.

 

The motorcycle is a dead giveaway that he ain't as old as most of us, but it appears to me that he came here and asked a valid question because he respected the fact that a lot of us old farts have done these kinds of things before and could provide some insight because of our knowledge and experience. He just miscalculated how crochety some of are........
When my son was younger and we had different points of view..........I used to ask him if he knew more now than he did 10 years ago. Then maybe I knew more than he did and he should listen to me. Now I'm in my 70s and he just turned 40.......and I'm learning some things from him.
We (us old farts) don't know everything, even though we can bluff the young guys most of the time.