79 250, what is this fitting? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Volfandt · 02-03-2018, 07:40 PM

79 250 w/the integrated head and 2bbl manifold. I'm going over this engine capping and/or removing unnecessary pollution and leaky vacuum devices.
I removed this fitting hoping it was in a water jacket but it wasn't. It had a small amount of soot or dried oil in it. The fitting is hollow with a small output port and a slightly larger output port. Whatever is generated in the void in the block will exit out both outputs.

**'68OrangeSunshine** · 02-03-2018, 08:19 PM

I'm not sure. Possibly an oil feed/return for PTO or Oil Bath Air Cleaner? Not the usual PCV fitting, but I am not familiar with the integrated head L6s.
Can you access an earlier L6 non-integrated head? It will bolt on fine. Then you could run headers.

**Wrenchbender Ret** · 02-03-2018, 11:03 PM

I'm thinking it is a vacuum outlet. With the intake built into the head it must have a passage to the intake. Pull the hose off & start the engine. You will find out what is beyond it.

Volfandt · 02-13-2018, 05:57 PM

You win the coveted "tain't a prize" Wrenchbender Ret LOL.
The fitting is a dual constant vacuum port. Best I can tell is the port is cast somewhere into the 3/4 intake. Just another oddity in this integrated head 2bbl 250....
I couldn't test until I got all the coolant & oil pressure senders situated.

Now to find an elusive vacuum leak which theres no telling where it'll be..

02-03-2018, 07:40 PM	#1
Volfandt Registered User Join Date: Jan 2018 Location: Knoxville TN Posts: 87	79 250, what is this fitting? 79 250 w/the integrated head and 2bbl manifold. I'm going over this engine capping and/or removing unnecessary pollution and leaky vacuum devices. I removed this fitting hoping it was in a water jacket but it wasn't. It had a small amount of soot or dried oil in it. The fitting is hollow with a small output port and a slightly larger output port. Whatever is generated in the void in the block will exit out both outputs. Attached Images

02-03-2018, 08:19 PM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,040	Re: 79 250, what is this fitting? I'm not sure. Possibly an oil feed/return for PTO or Oil Bath Air Cleaner? Not the usual PCV fitting, but I am not familiar with the integrated head L6s. Can you access an earlier L6 non-integrated head? It will bolt on fine. Then you could run headers. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 02-03-2018 at 08:55 PM.

02-03-2018, 11:03 PM	#3
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,190	Re: 79 250, what is this fitting? I'm thinking it is a vacuum outlet. With the intake built into the head it must have a passage to the intake. Pull the hose off & start the engine. You will find out what is beyond it.

02-13-2018, 05:57 PM	#4
Volfandt Registered User Join Date: Jan 2018 Location: Knoxville TN Posts: 87	Re: 79 250, what is this fitting? You win the coveted "tain't a prize" Wrenchbender Ret LOL. The fitting is a dual constant vacuum port. Best I can tell is the port is cast somewhere into the 3/4 intake. Just another oddity in this integrated head 2bbl 250.... I couldn't test until I got all the coolant & oil pressure senders situated. Now to find an elusive vacuum leak which theres no telling where it'll be..



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