My 1967 283 has plugs in these holes with out the square keyhole, on the china rail and just above the oil filter. Do they need to be removed for a rebuild? This looks like a PITA to remove them, but if I drill them out with progressively larger drill bits and then try to torch the remains out, have I really gained anything? Should I have the machine shop do it? Experience-based advice please.
Unless I am mistaken those are just a sofy plug, you can drill a hole in the center and use a slide hammer with a sheet metal screw to pull them. If you are getting the block boiled and intend to run a bottle brush through the galleys they need to come out. I have either gone back in with a replacement soft plug or tapped them and used a flush mount pipe plug.
the first picture..isn't that the threaded hole for the clutch Z bar support? (the thing about two inches above the square hole plug) if you're talking about something else, just ignore me.
No, I'm talking about the square hole plug. The one I have has no square hole, or any hole, in the plug. I get that the other was for the Z bar.
I usually try to get them out if they have the square hole. If not, just leave it there. I always remove the lifter oil gallery plugs and clean every oil passage as good as I can. I think you can reach in there from the oild filter side pretty well without removing your plug. Use a lot of brake cleaner and compressed air and you´ll be fine, I think.
I agree what Baumi has said. Also in the second pic. When you finish cleaning the block,Don't forget that top plug. you can not put it in after the head is on and it makes one heck of a mess if you forget . Also in small block chevys in the oil passage in the block where the oil pump bolts on there is a plug. Leave this plug out, you WILL HAVE OIL PRESSURE but you will not know you have no filtered oil. Some times when a block is hot tanked the shop will not put this plug back in. The filter will fill with oil and you will think everything is ok but it is not.
Leave it, do get the 3 in the front and back of the block (cam/lifter galleys) and the oil pressure port behind the intake though
Sorry squirrel, I'm at work and don't have my iPad. The other plugs are all out of the block, even the hidden one.
You are good then. The one just above the filter boss just taps right into the passage going to the filter, it can be used as an aux oil pressure port. Many years ago, I was the tear down guy for a motor shop. That's all I did all day long was disassemble and hot tank blocks and parts.
The simple prep work getting a block ready to build is mandatory in my book. Get all of the plugs out, grind the flash out of the oil drain back holes. Relieve the hole where the oil pump mounts so the hole in the block flows, like blending an exhaust port. If you don't have a tap set have the machine shop tap the gallery plugs before they hot tank the block. Use short plugs in the front galleries. Too long a plug will go in deep and actually block the flow.
I know this is an old thread, but I've just run into these plugs myself. 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. It would be folly to leave these plugs installed when rebuilding a pump or motor, the same would apply to any force lubricated machine. The concern is that contaminants can sit behind the plug (because there's no flow path to flush them out) and in certain circumstances can be dislodged and circulated into a critical area, causing lubrication failure and subsequent damage. Removing the plugs before rebuilding allows for inspection and remediation if any issues are found. 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). I'm also going to start a new thread on the subject.
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