I recently pulled the heater core out of my car and don't plan on reinstalling it. I want to plug all of the lines I no longer need. The engine is an 86 with TPI. I have the two lines that come out infront of throttle body and one that comes out to the passenger side of the car. I do have a NPT fitting in the top of my water pump. Please let me know which line needs to go into the NPT fittting and which lines I can plug. Pictures of past work would be great! Thank you all for your help.

 

I would just plug both lines. My Z28 is a 92 but my vette is an 86. If it's anything like this, and you want to keep coolant going through the throttle body, ( I think it runs through the throttle body to warm up for some kind of a computerized "choke" circuit) just remember, the waterpump always "sucks" and coolant out of the manifold "blows". That is the best way to remember the direction of coolant flow in most all engines. Do you have a heater connection on the radiator just below the fill neck that is being used? If so, this is also a "return" line and can be considered the same as a waterpump connection ("sucks"). With that rule of thumb, you can plug or route hoses anyway that conforms to that info........BTW, in most performance applications, you would no longer want to run coolant through the throttle body as cooler air makes more hp. Don't know if it would set a code because of lack of warmup or not. Not sure if it would negatively effect the MAT sensor or not. Might want to check that on the ecm forum first. My car was chipped when i bought if with a custom made chip so my computer may not care. Ideal would be no hot water in the throttle body though. Then you can just simply plug all removed hoses. If there's no negatives with the MAT sensor (assuming your car uses that), I know there should be no negative effect on overall cooling. The only hoses then required for coolant are the 2 radiator hoses. The waterpump bypass if the pump is stock or a stock replacement is cast into the pump itself so there are no other hoses necessary. Good Luck and run deleting the coolant hoses on the throttle body past some others on the computer related forum.