Can anyone tell me what this thing is?
 

I'm currently starting a 250 rebuild maybe boost ��but for the life of me
I can't tell what this is.
I'm prepared for the shaming.
Screw like object below valve spring.

Re: Can anyone tell me what this thing is?
 

Looks like a cylinder head to me. What specifically are you referring to?

Re: Can anyone tell me what this thing is?
 

Ah my bad
The screw like object below the valve springs center of picture

Re: Can anyone tell me what this thing is?
 

Oldsmobile?

AIR injection ports for secondary air.

Re: Can anyone tell me what this thing is?
 

I updated the photo if that helps

Re: Can anyone tell me what this thing is?
 

Im not sure what it came out of i believe its a 65 250

Re: Can anyone tell me what this thing is?
 

I Did some more digging and it sounds like you may be on to something the block code matches the olds.

Re: Can anyone tell me what this thing is?
 

Looks like Bigdav160 got it. If there is one plug at each exhaust port, they are in the position where the Air Injection Reactor pumped air into the exhaust to help with more complete burning of the exhaust when the choke was engaged. Once the truck warms up enough, the thermal vacuum switch opens and the system freewheels.

That system began to be used in '66 on many vehicles.

Re: Can anyone tell me what this thing is?
 

Cool thanks guys I stripped one trying to get it for a cleaning nice to know it doesn't really matter anyways.