I recently had a number of over cooling difficulties which caused very poor gas consumption. Like many of us I installed a 160 stat (now 180F) and then modified my dual fans to cycle on at 175 or so. Trouble came because the fans brought the temp down to 125.... this was due to poor sensor placement which resulted in a on\off cycle of some 50 degrees. I also had a very slow warmup period which seems to be a normally feature of the F bodies. The large air dam and the cooling bypass loop appear to be the problem. My bypass loop runs, block (bypassing the TPI) to AC\Heater control valve to Heater core (when on) to oil filter cooler to radiator return inlet. It appears that this bypass loop is more effective then on most cars, I also noted that when replacing the AC\Heater control valve (the plastic gernade) what appears to be a 1/8" bore washer loose inside and I now wonder if this may have been a restrictor to limit the bypass flow rate. To speed up the warmup cycle I have since placed a 3/16" restricter at the radiator return inlet.
Has anyone more information concerning this bypass loop?

 

The bypass is a waste of time, it accomplishes nothing. The purpose of warming the throttle body is to prevent icing of the idle passages and erratic idle. I have posted this more than a few times, but icing can occur on a 70 degree day. My Honda sportbike VTR 1000 has coolant thru the 48mm carbs. I took it off and I could be sitting at a light on a summer day and it just died. Warming the throttle body helps stabilize the idle and offers better driveability overall. At fast acceleration or WOT that little bit of heat thru the TB makes no difference at all. Don't confuse this with a cold air induction package, they are 2 totally different animals.

 

I did it so I wouldn't have to drain coolant to pull off the TB. I seem to do that more often than changing the thermostat as routine maintenance. Other than that, I agree, there's no advantage at all. For some, it's not even an advantage, as they don't mind draining coolant.

 

Thanks for the info, this sounds right as I have noticed that even though I'm sure the IAC adjust is correct my Camaro has died at idle a few times on warm 70F/wet days. High flow air passing small openings can get very cold. I may need to rethink the TPI bypass when our Aussy days get down to a cool 60F.