What is this hanging off my HEI?

[BJohnson]

I've searched YouTube and various forums. I stumped a few guys at the car show tonight. Anyone have any thoughts on what this is hanging off my HEI? My 1979 C30 camper special dually has a 454 and had factor AC and Cruise... before the previous owner put an Edelbrock 1406 and Performer intake on it.

 

[HotWheelsBurban]

I've searched YouTube and various forums. I stumped a few guys at the car show tonight. Anyone have any thoughts on what this is hanging off my HEI? My 1979 C30 camper special dually has a 454 and had factor AC and Cruise... before the previous owner put an Edelbrock 1406 and Performer intake on it.

Do you have a picture of this mystery item by chance? All a '79 Chevy truck HEI unit should have on it is the big tab on one side of the top, where the coil terminals go, and a vacuum advance unit towards the bottom.

 

[Radiohead]

Could it be an idle stop solenoid perhaps? I saw that in the wiring diagram too, and wondered what it is.

 

[BJohnson]

Do you have a picture of this mystery item by chance? All a '79 Chevy truck HEI unit should have on it is the big tab on one side of the top, where the coil terminals go, and a vacuum advance unit towards the bottom.

I don't right now, but I will tomorrow. It looks like the rounded rectangle relay similar to the camper special dual battery relay. Then, it goes to a two prong plug that isn't attached to anything.

 

[BJohnson]

Could it be an idle stop solenoid perhaps? I saw that in the wiring diagram too, and wondered what it is.

It does say speed switch solenoid, so I wonder if it was AC related... or not. I don't know. But, it might be that.

 

[Backyard]

my guess is it would be for a high idle solenoid to bump the rpm up for warmup. just a guess i would have to see the rest of the diagrams to see

 

[bucket]

I don't remember what it was for, but iirc @Craig 85 does know. Pretty sure anyway. There was a thread about it a couple years ago.

 

[Craig 85]

My '80 C20 3+3 454 non A/C, no cruise did not have that, but my "85 K30 454, A/C, cruise does. It mounts at the rear of the driver side valve cover. It triggers the vacuum pod on the front of the carb between 1600-1900 RPM to prevent back fires when decelerating. It's a different set up than what small block have with A/C. Those bump the idle when the A/C is on.

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