Odd threaded bung.
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Joined: Aug 2006
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From: Columbia Missouri
Odd threaded bung.
Okay, I don't revall ever seeing this bung when the heads were off of this block and I can't find it in detail in the pics I took before the heads went on.
Basically I saw it when I was inspecting the silicon bead for the intake, and wondered what it was and why it was open like that.
I stuck an awl down, and it is not plugged...or at least the awl didn't bottom out. I'm worried it leads to the water jacket but I can't imagine why it wouldn't have a plug.
Does anyone know what that bung is, peeking out from under the head, next to the oil port?
Basically I saw it when I was inspecting the silicon bead for the intake, and wondered what it was and why it was open like that.
I stuck an awl down, and it is not plugged...or at least the awl didn't bottom out. I'm worried it leads to the water jacket but I can't imagine why it wouldn't have a plug.
Does anyone know what that bung is, peeking out from under the head, next to the oil port?
Last edited by Durango_Boy; Apr 16, 2008 at 02:43 PM.
Thread Starter
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From: Columbia Missouri
Burning Brakes
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From: Chicago IL
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From: Crossville TN
If they removed it, they had an obligation to re-plug it...or, at least, to remind you that it should be re-plugged. I'd certainly call the shop and give 'em an earful. 
I imagine you also have the headers bolted up.... {Dang!}
I imagine you also have the headers bolted up.... {Dang!}
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Thread Starter
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
I would but it's totally my fault. That's something I should have caught before the head went on. I'll just have to pull the intake, rockers, head, and plug it, and re-assemble.
Burning Brakes
Joined: Feb 2000
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That's no pressure port, that hole is there because that's how they drill the cam oiling passage from the main vertical oil feed, it should be plugged, the one next to it that's uncovered by the clearance in the manifold is the pressure port.
If that plug isn't there I would check if the plug down in the block in the pressure port is there, if left out, no filtered oil for you. It's installed from the main bearing side and sits about 1 3/8 inch down from that end (the first inch is wider than the 3/8 plug so the plug is actually inserted 3/8" into the correct size bore)
If that plug isn't there I would check if the plug down in the block in the pressure port is there, if left out, no filtered oil for you. It's installed from the main bearing side and sits about 1 3/8 inch down from that end (the first inch is wider than the 3/8 plug so the plug is actually inserted 3/8" into the correct size bore)
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From: Columbia Missouri
If that plug isn't there I would check if the plug down in the block in the pressure port is there, if left out, no filtered oil for you. It's installed from the main bearing side and sits about 1 3/8 inch down from that end (the first inch is wider than the 3/8 plug so the plug is actually inserted 3/8" into the correct size bore)
Very good info, thanks. Okay, I got the top end pulled off and a plug installed. Now, I understand the last plug is UNDER the main cap, which requires a removal of the oil pan, and rear main. Not a HUGE deal but I would rather not go through all that trouble.
I did some research, and there is actually a test to see if that plug is installed. Using an old oil dipstick, you go straight down through the upper oil pressure sender port. Mark where it stops. If it stops at the part line of the oil pan and block, then the plug is NOT installed. If it stops about an inch above that, it IS installed.
Sound right?
I tested, and the dipstick stopped about an inch above the part line. I would assume from this that the plug is installed. However, is this a sure enough test to chance it?
Last edited by Durango_Boy; Apr 17, 2008 at 09:25 AM.
Thread Starter
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From: Columbia Missouri
I'm confident the under-main plug is installed. I ran the dipstick down my 400 block, and the measurement matched the block in question perfectly.
I hate uncertainty but this test, performed on two blocks that matched, has left me with a positive feeling that that plug is not missing.
Anyone concur?
I hate uncertainty but this test, performed on two blocks that matched, has left me with a positive feeling that that plug is not missing.
Anyone concur?
Team Owner
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From: Crossville TN
D_boy... Just call your machine shop as ask them if they removed the lower plug. If they do a lot of Chevy heads, they have a "standard" procedure they use. They'll be glad to tell you what was [and wasn't] done.
Thread Starter
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From: Columbia Missouri
I did, but they didn't have a clue if they forgot or not, this block was done months ago and they don't remember stuff like that.
Team Owner
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From: Crossville TN
Too bad. I think the "rough" measurement method you used should be pretty good. If you have someone you know who does this a lot, you might run it by him first. Good luck with the fire-up! 