hi,
why am i smelling antifreeze after header install,and only when i have my hvac on,when its totally off,it goes away,turn on vent,its there???cant figure it out,i didnt touch nothing to do with the antifreeze....anyone have any ideas?
thanks
and also,why is my car now sometimes reving around 2000 rpms,like rev the engine,and it stays at 2000 a couple sec. and works its way down??got me on this one

 

Maybe your heater core gave out right after the header install. A big coincidence, I know. But I'm just takin a stab in the dark here. My car does that rev thing too, but really only when I'm driving like grandpa, and shifting it at like 2200. It has a tendency to stay there till I hit the next gear. Never really does it when I just rev it. Then again I don't have headers. Good luck!

 

On the passenger side of the engine bay are metal lines that run from the fire wall to near the battery. These are connected to the water pump with rubber hoses. These metal lines supply the heater core with engine coolant. They are very close to the manifold on the right side of the engine. chances are when you installed the headers you bumped the metal lines hard enough to crack them. However, you should be seeing a puddle or a drip. Also if there is a leak, you should be seeing the coolant level go down.

Be careful, a leak will introduce air into the system and LT1's have problems with air in the coolant system.

Pull the carpet back under the glove box and see if it's wet. check the back of the glove box door and down the firewall also.

 

that is your most likely suspect...also on the drivers side the coolant temperature sensor sits screwed into the block under the headers, and its very easy to bump when putting them in. Make sure this isn't broken off.