The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 1974 GMC 15 Hundred

Dead Parrot · 09-10-2014, 11:02 AM

Your air cleaner THERMAC gizmo connects to the dusty looking capped pipe coming out the side of the carb. The small clean looking vacuum pot end connects to the small clean pipe on the carb. There may be a missing piece as the picture I have of a 74 carb shows that pot hose connector rotated about 90 degrees so it mostly points at the carb connection. Or a PO may have used the wrong pot during a repair.

The THERMAC flapper pot connects to a temp sensor in the air cleaner, then from the other side of the temp sensor to the carb.

09-10-2014, 11:02 AM	#8
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,661	Re: 1974 GMC 15 Hundred - Vacuum Hose Questions Your air cleaner THERMAC gizmo connects to the dusty looking capped pipe coming out the side of the carb. The small clean looking vacuum pot end connects to the small clean pipe on the carb. There may be a missing piece as the picture I have of a 74 carb shows that pot hose connector rotated about 90 degrees so it mostly points at the carb connection. Or a PO may have used the wrong pot during a repair. The THERMAC flapper pot connects to a temp sensor in the air cleaner, then from the other side of the temp sensor to the carb.