nothing is wrong with the heater core. the go i bought the car from said the heater lines are looped so they don't run into core? I have no idea honestly. help me out!

Take a look on the firewall (engine bay side). Look behind the motor, towards the passenger side. You'll see a pair of smaller diameter lines (around 3/4" if I remember right) running to a valve, and then into bulkhead fittings on the firewall itself. Are they actually connected, or tied together other than the picture below?



It'll look something like this. We can safely assume you still have a motor in the way.



If those lines are connected as shown, warm the car up. Both lines on the right (the ones going through the firewall) should be hot. This indicates coolant is flowing through the core assuming the valve is open(or they're looped together behind the firewall...) You can manually open the valve on the left to test if your control cables are broken/seized if it doesn't move when you set the hvac to heat in the cabin. There's a chance the heater core is clogged and may need to be flushed (even if both lines are hot. It may not flow enough to heat the car. Or the air mix door on the blower assembly isn't working)- but with the previous owner saying it's looped you'll need to find out where he made the modification. If it's on the cabin side of the firewall, you'll have to pull the dash apart to check. Hopefully it's in the engine bay.

None of the above should take more than 5-10 minutes to quickly check.

Also, what's the car setup? Stock motor/swapped. Is anything else related modified?

Probably won't solve the issue, but it should help narrow things down. Hope it helps.

The motor is a blacktop 20v in 85 gts. Sorry i should have been more specific!

might not have the inlets and outlets for the heater on that engine, depending on the water line kit being used.

Please upload a pic of your engine.

Ok I will when I get home.