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What are these holes on my intake?

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Old 09-11-2023, 06:31 PM
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Car: 1987 Firebird Formula
Engine: 305 Carbureted
Transmission: 700r4
What are these holes on my intake?

Can anyone tell me what these holes on the side of my intake are? It’s an Edelbrock Vortec performer rpm and the whole are 1/2 inch. I’m confused what I could possibly use these for. Also is the hole under the carb the only vacuum port? Because I have a brake booster to run to it and a pcv so am I just supposed to run them to a T kind of thing?


Old 09-11-2023, 06:53 PM
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Re: What are these holes on my intake?

Most likely exhaust ports for an EGR system. It should line up with the center exhaust crossover ports in the cylinder heads.
Old 09-11-2023, 08:46 PM
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Re: What are these holes on my intake?

Originally Posted by ULTM8Z
Most likely exhaust ports for an EGR system. It should line up with the center exhaust crossover ports in the cylinder heads.
thanks man, I’ll just plug them then
Old 09-12-2023, 06:04 PM
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Re: What are these holes on my intake?

For water heating the plenum in cold climates.
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Old 09-13-2023, 04:31 PM
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Re: What are these holes on my intake?

there not for egr, it's for an old style thermo choke, the exauast heats up en element and the choke linkage opens the choke up, that's y its under the linkage, if it were egr it wouldn't be threaded, it would be part of a triangular flange w a hole going to the intake and 2 bolt holes

Last edited by lewandom; 09-13-2023 at 04:34 PM.
Old 09-13-2023, 08:35 PM
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Re: What are these holes on my intake?

Originally Posted by lewandom
there not for egr, it's for an old style thermo choke, the exauast heats up en element and the choke linkage opens the choke up, that's y its under the linkage, if it were egr it wouldn't be threaded, it would be part of a triangular flange w a hole going to the intake and 2 bolt holes
Not even close, the choke thermostats use a rectangular opening with a bolt hole on each end. Those holes are there to route coolant under and around the plenum since vortec heads do not have an exhaust crossover passageway to heat that area. I have owned and run that manifold and had the coolant plumbed up.
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Old 09-14-2023, 11:07 PM
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Re: What are these holes on my intake?

learned something new, I was sure they were for an old thermo choke
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