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gmebey · 08-23-2011, 05:52 AM

I'm really confused after several hours of digging for information on factory GM HEI vacuum connections.

My project truck is turning out to be more of a mess than a project. The prior owners did some weird stuff, and to the list HEI and carburetor mess.

First issue, I suspect I have a intake manifold and carburetor mismatch:

The spacer/gasket plate below the carb did not seal the vacuum ports on the bottom of the carb (Elderbrock Q-Jet 1902).....PLUS the intake manifold is from what I think is a post 1974 and has a the EGR passage under the carb. A trip to the auto parts store yielded no solution without using a 1" riser.....either the vacuum or EGR passage is uncovered.

I need a solution, is there an off the self option? At this time I'm leaning to making a plate out of aluminum.

Second issue, the distributor has been switched out for a factory HEI.

I suspect the vacuum is not plumbed right. I'm still lost after reading several articles.

I have two simple questions:
1) Did the original factory HEI use a vacuum canister?
2) Where did the original factory HEI get it's vacuum source. Manifold, not ported at the carb or ported at the carb?

08-23-2011, 05:52 AM	#1
gmebey Registered User Join Date: May 2011 Location: Fort Collins, Colorado Posts: 95	HEI vacuum connections I'm really confused after several hours of digging for information on factory GM HEI vacuum connections. My project truck is turning out to be more of a mess than a project. The prior owners did some weird stuff, and to the list HEI and carburetor mess. First issue, I suspect I have a intake manifold and carburetor mismatch: The spacer/gasket plate below the carb did not seal the vacuum ports on the bottom of the carb (Elderbrock Q-Jet 1902).....PLUS the intake manifold is from what I think is a post 1974 and has a the EGR passage under the carb. A trip to the auto parts store yielded no solution without using a 1" riser.....either the vacuum or EGR passage is uncovered. I need a solution, is there an off the self option? At this time I'm leaning to making a plate out of aluminum. Second issue, the distributor has been switched out for a factory HEI. I suspect the vacuum is not plumbed right. I'm still lost after reading several articles. I have two simple questions: 1) Did the original factory HEI use a vacuum canister? 2) Where did the original factory HEI get it's vacuum source. Manifold, not ported at the carb or ported at the carb?