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Re: 1951 Packard 200, 288 engine. Yesterday I was enjoying an under hood experience of many, many months without any significant problems or heartaches.....Just kinda looking around at the engine. I noticed the coiled spring on the forward facing part of the exhaust manifold, that engaged the shaft of the heat riser valve, is lying on the floor... it is in pieces. How can I tell if the valve is frozen in an open or closed position? Can I just wire it open? I understand why the valve exists, however I am concerned with the exhaust gas restriction and don't particularly care if the valve works as designed....Just as long as it's open... Your comments please.
Regards, Steve.

Yeah, unless you're in an exceptionally cold climate your car can function satisfactorily with the valve removed or permanently open. If the counterweight is still on the other end of the shaft, it's open when the counterweight is down. The bimetallic spring holds the valve closed when cold and as it heats if releases part of it's tension by unwinding and allows the counterweight to overcome the force of the spring. Of course the shaft must move freely for this to occur. Some folks have removed the exhaust manifold and drilled it to accomodate stainless bushings for the shaft - usually not necessary but elegant.

I just took a look at my NOS and yet uninstalled exhaust manifold. When the weight is down the flapper plate blocks most of the hot exhaust gas from hitting the bottom of the intake manifold. In operation when the engine is cold exhaust gas warms up the intake gas charge, as the engine warms up the flapper diverts the hot exhaust away from the bottom of the intake. My old exhaust manifold was missing the flapper and it made hot starts a real pain as it would boil the gas in the carb and dump it into the intake. I wouldn't remove the flapper Just run it with the weight in the down position.

It would be best to wire it open if it is not functioning.

But you should replace the spring and get it working.

Years ago I did this on a slant 6 Dodge.It had a heat riser valve, a tin stove on the exhaust manifold with a vacuum flap on the air filter, and an automatic choke.

It started and ran like an old car. Kind of balky but not too bad. So I did a tuneup which helped a bit.

Then I fixed the heat stove replaced the thermostat in the air filter, and replaced the automatic choke.

What a difference! I was amazed. The motor started and ran like it had fuel injection and warmed up in half the time.

Since then my policy would be to put the choke and heat riser back the way the factory had it and tuned to factory specs. It does make a difference to the way the car starts and runs.

Phil, good point about not removing it, I agree fully. If you must, wire it open. The heat riser on my 34 Eight is functional and the engine performs flawlessly; on the 56 Carib I removed it completely and regret it, though I have no hot start problems; next time I do an exhaust system I'll put it back - in the winter (below freezing) it's a little balky for the first 90 seconds or so.

G'day Steve,
for including your '51 200 Touring Sedan in the Packard Owner's Registry.

And also for including your '53 Clipper Deluxe Touring Sedan, looks good!

Hi Rusty O......I've been rethinking my action on whether to replace the heat riser spring and if needed the valve too. I don't know why, maybe it is as easy as......I can't stand having something broke" Would you know where I might find a replacement spring???

I'm not Rusty O, can I answer anyway? You can buy the spring from Max Merritt, his catalog is on-line. And I think it's a wise decision to decide to repair it, it was there for a purpose and it's nice to have all the features of our cars functioning as intended. Part# 419425, $25.00

Owen, thank you for directing me to Max Merritt.