Put a restrictor in that line, though. A big 5/8" line bypassing your radiator completely isn't the best of ideas.

Kind of off topic

But I am keeping my heater core for now because I still drive my car as a street car.

I’m converting to all -10 AN lines and fittings for the Heater circuit. So I welded on AN bungs to an NB heater core and I am going to use AN bulkhead fittings at the firewall. No hose clamp fittings anywhere.
some trivia.
NA copper brass heater core weight = 2.0 lbs.
NB Aluminum heater core weight =1.0 lbs.
The cores are slightly different shape but they are interchangeable if you swap the whole mode housing. Everything else on the mode housing is the same NA to NB but the shape and material construction of the heater core.

The other thing I did is put a thermostat in the Heater core line. It shuts the flow to the heater core to a trickle when the coolant temp gets over 190 F sending all the flow to the radiator for more efficient heat transfer.

Bob

when you do this can you post up pics? i hate hoses and clamps. lol

The NA copper heater core can be converted to AN without too much issue. A 1/2" copper female FTG fitting fits perfectly into the end of the copper heater core tubes. Solder that sucker in there and grab a couple 1/2" to -10 fittings. I already soldered the fittings in and the AN conversion is coming soon as my old hoses are starting to balloon near the end.

I know it wouldnt be to difficult, i just like pictures! :giggle:

Who doesn't love pictures :p ... just offering another solution as opposed to tearing the dash out and swapping to an NB unit and welding AN bungs to the core itself. Soldering is a lot easier than TIG.

The dash isn't coming out for a few weeks yet but I have all the parts worked out and the heater core modified. Should have the motor swapped on my 323GTX this weekend to have another driver then start working on the winter projects for the Miata.

Bob