I have a 1978 chevy scottsdale k10. I put headers and true duels on it, so its strait from headers then about 4 feet of pipe then the flowmasters. Well I was going down the rd one day and my head gasket blew, reason I knew bc it was smoking out the driver side exhaust and not the passanger side. So I drove it on home maybe 10 miles or so easy. I changed the head gaskets on both sides and put er back together and seemed like she was doing fine when I cramked er, till I noticed it was only heating out the driver side pipe. I went over and felt of the passanger side pipe and it was blowing cold air. This was after I had let her run, warm up and idle down. Please tell me you can tell me what would cause this. The only other thing I did besides new head gaskets and intake gaskets was flip the flap on the carb to where the 4 bbl would open up more than it was suppose to I assume. Thanks for any help!