Back when my throttle return spring was lost going down
the road it knocked off the heat riser spring as well.
I had it unhooked over the summer and just hanging on
the shaft. Well with it getting colder I noticed it's
taking longer to get the idle smoothed out so I wanted
to add the spring back to the heat riser. I'm cheap and
wanted a less pricey solution than the $18-27 from the
vendors plus shipping. I began to wonder if a choke
thermostat spring would work if it was removed from the
plastic housing. I spent an hour going through all the
pictures on Autozone's website for choke thermostat.
I found one that visually was similar to the picture of
the heat riser spring. Since it was less than $10 I
thought why not take a chance and see if it'll work.
So I ended up ordering a BWD # TH77 from O'Reilly's
since they could have it the next day.

Saturday morning I set about removing the spring from
the housing. Before & after.
I had to get a razor blade down between both sides of
the spring and the plastic shaft to get it loose. Once
it was loose the inner coil was smaller than the shaft
on the heat riser so I had to work a screw driver in
the coil and get it enlarged. But other than that it
fits perfectly on the heat riser shaft and hits the
post above it. Best thing is once it's warm it allows
the weight to fall over into the closed position where
the previous spring didn't unless the throttle was
goosed. My camera didn't take a clear picture of it
installed I'll try another camera at lunch and link a
picture if I get one.

If you want to get one of these chokes the vehicle I
remember it fitting was a 1970 AMC Gremlin, or its BWD
# TH77, Standard has it as # CV77.