How take off header core

indicates a blown head gasket
have a compression test done
then check for thermostat stuck closed and blocked radiator cores

the heater core needs replaced

You are wanting to put headers on a Blazer? Power to ya, dude! I doubt if anyone can tell you how to do it other than unbolt the existing manifolds and bolt the headers in....hope they fit...

Have you thought about what you are going to do with the REST of the exhaust system? Like the O2 sensors, catalytic converter, etc.? Install headers because it sounds cool and all your buddies will be impressed with all the "power" it gives your Blazer...only to totally mess up your fuel control and have it run like ****???

I don't get it.....

Good luck

You trucks heater core is leaking inside the dash heating vents, the air blower motor blows through the heater core and then you smell the leaking coolant in the form of a sickly sweet vapor. You will need to replace the header core, this is a fairly big job and in most cases best left to a professional.

Not sure what a burning header smells like, but I would expect two possible smells. First, if the blower motor itself is going, you might smell the windings getting hot - like a transformer burning. If this were the case I would expect that the motor wouldn't spin on the low speeds.
The other smell you sometimes get is when the heater core leaks. Then you will get a coolant smell inside the car and sometimes (usually) a wet carpet as well.

You have still got air in the system.Remove the Feed back pipe from the header tank and wait for all the air to come out while the engine is running making sure you are toping up the header tank at the same time Dont allow header tank to run dry while doing this.Good luck

Specifications Core Size: 28-1/4 X 17-1/2 X 1-3/8 Inlet Header: 2-1/2 X 18-3/4 Outlet Header: 2-1/2 X 18-3/4 Inlet Connection: 1-5/16 DRIVERS SIDE Outlet Connection: 1-9/16 PASSENGERS SIDE

no they can't

If you are talking about the brass tubes which are soldered into the core headers, they are not supposed to turn or be removed except with soldering heat. (600 to 800 degrees F.)

This looks like you have a blown header gasket. You probably can smell anti-freeze in the exhaust.
You can verify the problem by have a pressure test of the cylinders. At least one will not hold pressure. The cost of the new gaskets is cheap compared to the labor to install them. Every item with a gasket that is removed to get the header off will require a new gasket.
Valve cover gasket$
Intake manifold gasket$
Exhaust manifold gasket$
Header gasket
etc$