finally got my 69 off the ground and took a look underneath. found out why it was so loud and smelly ... one loose nut holding each exhaust pipe to each of the headers!
noticed something unique to the passenger side. between the pipe and the header is about a 1-1/2" thick flange with a knob on the outside. when I spin the knob a half turn, feels like I am opening and closing a damper on a fireplace. is this what is called an "exhaust crossover valve" ?
if not what is it? it doesn't seem to be attached to anything else to "make it work". I don't know how to know if this is helping/working or harming/not working.
any thoughts?
thanks

Its called a heat riser----normally there is a spring or vacuum pot that closes it when the engine is cold to force the exhaust from the right side of the engine to go through the intake under the carb to warm it up quickly then opens to let the exhaust out normally---if its not working the engine will just warmup a little slower.........................Dan

thanks dan ... in your opinion should I replace/repair it or just get rid of it? admittedly in the new york winter it does take a long time to warm up. spring, summer, and fall runs pretty fine.

is an "exhaust crossover valve" a different part that does the same thing? or a different name for this part?

thanks again,
vincent

Its probably the same thing but I'm not to sure on that as I've never heard it refer to in that way...........I think it probably is a toss up on whether to fix it or leave it alone... price and things like if you can get the bolts out without breaking them should dictate whether to fix it or leave it for now---its not a big deal either way..............Dan

If it is not operating automatically, make sure the valve is open. If it is closed all the time, the exhaust gasses will pass thru the engine all the time, even after it is up to operating temp. You do not want that to happen. It will cause the engine to run hotter than normal and could cause other problems.