Block pic. What is this hole used for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue4x4 · 12-18-2005, 09:37 PM

Not my block, But can anyone tell me the purpose of this hole? I just finished installing my heads and realized that a portion of this hole is showing. I really don't want to pull the heads just to find out it's nothing. Thanks

70c10swb · 12-18-2005, 10:04 PM

knock sensor?

matthufham · 12-18-2005, 10:30 PM

good question, you're right about oil pressure.

mjrmn · 12-18-2005, 11:06 PM

WOW that is a good question-I just went thru my Chevy power catalog and cannot find that hole in any of the pics or descriptions.
Is the hole tapped for a plug?
Can you tell if it just stops at the bottom or if it leads to an oil or water passage?
I would think that if the head only partially covers it that it is probably nothing but I am not sure.
Hopefully someone else will have an answer for you

jhow66 · 12-18-2005, 11:14 PM

For factory access for a drilled passage. Will be plugged. Almost impossibe to remove plug but no need to remove it.

Blue4x4 · 12-18-2005, 11:23 PM

Thanks jhow66. I was able to look inside the hole with the head on and see an allen screw.

Blazer1970 · 12-19-2005, 07:42 AM

Yup, it's a cross drill.

*hoser* · 12-19-2005, 08:18 AM

Quote:

Originally Posted by Blazer1970

Yup, it's a cross drill.

Cross drilled to where? if its a oil passage the plug should be removed and the passage cleaned if the block was cleaned IE boiled or cooked because it could hold crap that could later be introduced into the oil system.

Leonard1 · 12-19-2005, 09:49 AM

Hey guys, still pretty new here, but I'll give this a shot.

I think that is the access to remove the little plug that blocks the oil return passage. It looks like the plugs that go above the camshaft. When rebuilding a block, I always remove it, and the plug, and rod out all the old sludge. BTW, if you leave that plug out, you are bypassing the filter.

The SDPC catalog has a great diagram of this

12-18-2005, 09:37 PM	#1
Blue4x4 Senior Member Join Date: Mar 2003 Location: Sparks, NV Posts: 790	Block pic. What is this hole used for? Not my block, But can anyone tell me the purpose of this hole? I just finished installing my heads and realized that a portion of this hole is showing. I really don't want to pull the heads just to find out it's nothing. Thanks Attached Images

12-18-2005, 10:04 PM	#2
70c10swb no brain no headache Join Date: Jan 2005 Location: Cape Cod MA Posts: 567	Re: Block pic. What is this hole used for? knock sensor? __________________ 1996 GMC Sierra z71 1970 SWB 2wd (project)

12-18-2005, 10:30 PM	#3
matthufham Registered User Join Date: Feb 2005 Location: Carl Junction, Missouri Posts: 2,061	Re: Block pic. What is this hole used for? good question, you're right about oil pressure.

12-18-2005, 11:06 PM	#4
mjrmn '67 K10 Work In Process Join Date: Feb 2004 Location: Delano MN Posts: 163	Re: Block pic. What is this hole used for? WOW that is a good question-I just went thru my Chevy power catalog and cannot find that hole in any of the pics or descriptions. Is the hole tapped for a plug? Can you tell if it just stops at the bottom or if it leads to an oil or water passage? I would think that if the head only partially covers it that it is probably nothing but I am not sure. Hopefully someone else will have an answer for you

12-18-2005, 11:14 PM	#5
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Re: Block pic. What is this hole used for? For factory access for a drilled passage. Will be plugged. Almost impossibe to remove plug but no need to remove it. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-18-2005, 11:23 PM	#6
Blue4x4 Senior Member Join Date: Mar 2003 Location: Sparks, NV Posts: 790	Re: Block pic. What is this hole used for? Thanks jhow66. I was able to look inside the hole with the head on and see an allen screw.

12-19-2005, 07:42 AM	#7
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Re: Block pic. What is this hole used for? Yup, it's a cross drill. __________________ Tim

12-19-2005, 09:49 AM	#9
Leonard1 Registered User Join Date: Nov 2005 Location: Paducah, Ky Posts: 393	Re: Block pic. What is this hole used for? Hey guys, still pretty new here, but I'll give this a shot. I think that is the access to remove the little plug that blocks the oil return passage. It looks like the plugs that go above the camshaft. When rebuilding a block, I always remove it, and the plug, and rod out all the old sludge. BTW, if you leave that plug out, you are bypassing the filter. The SDPC catalog has a great diagram of this Last edited by Leonard1; 12-19-2005 at 09:50 AM.



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