I have an 85 TA with 305 TPI, the distributor has a regular looking cap, with no coil on top.
Does my car have a coil mounted somewhere else?
What is the difference between the distributor cap I have, and the HEI distributor cap?
Would HEI be an upgrade from my setup?

I'm doing a complete tune-up.

 

"HEI" kind of got over-used by the factory, sort of like they did with "Vortec".

"High Energy Ignition" is what they called their first general-use non-points, electronic ignition. Even that is a bit of a misnomer, but I digress.

At first, all "HEI" distributors had a large cap with the coil in the cap. Later they made some small-cap versions that had the coil mounted remotely when under hood space became a problem, but still called it "HEI".

So, if yours is a "regular" looking cap, it's probably of the latter variety and has a coil mounted remote to the distributor.

 

The in cap coil HEI was a bad idea, epoxy coils are prone to fail by default as the epoxy holds in heat, heat kills coils, they then crammed it under the cap where it gets no air, bad idea.

Why it was removed.

Though still an expoxy coil, get a oil filled can coil.

I know people think its some old design, but it works better, as the oil cools the coil.

 

Thanks for the help.
I'll keep the oil filled coil in mind when I start buying parts.