ancient tech

[Chopper]

Question for my wrench-type friends:
'49 Hudson Commodore 6....straight 6 w/ intake and exhaust on the right...almost intertwined. The carb sits atop the exhaust manifold and there is a flap, actuated by a (bimetal?)spring, that connects carb and exhaust.
WTF??
Exhaust reburning ? Can't be a choke thing since it's temp controlled....no electronics...no vacuum...no cables. Completely automatic and mechanical. I can't even tell if it works, but the car starts and drives just fine.
Heating the incoming aircharge? Is this where Smokey Yunick and GM got the idea?
I'm stumped.
***I gotta find a Hudson nutter....they're out there somewhere. This car is beautiful. Ron got himself a nice old ride. I need to find a heater core for it and the cable driven wipers barely work. It's been a showcar for some time...it'll be good for it to be driven again....When I get it all sorted

[Y33TREKker]

Why do you think it's not a choke? Not so long ago on a 1983 Mustang GT with a four-barrel Holley carb, that's very similar to the way it's cold start choke was set up.

[Bulldoggie]

It's part of the choke. When the bi-metal heats it allows the choke to fully open.
Many cars and trucks had them.
Was part of the linkage missing?

[Bulldoggie]

I believe they worked with a spring to close the choke when you stepped on (or tapped on) the throttle peddle before starting, when the engine was cold.
If it was warm it would stay open.

[bigblock8396375]

http://www.dodgepilothouseclub.org/know/riser/Exhaust%20Heat%20Risers%20Debunked.doc. Maybe this will exlPlain it?

[Chopper]

THANK YOU Big Block

That explained it perfectly.....It didn't seem like a choke, because it only seemed open when it's warm, and why would you choke a warm engine. I've seen the same sort of thing on a couple Packards here, but it was always deactivated for some reason...usually with a hand choke added under the dash or somewhere. The intake and exhaust runners are actually fastened with shared bolts. That incharge is WARM.
Too many of these old engines are going away. These old guys want Vette power in everything, and this one's no exception....everytime he comes to visit it he makes a comment about a LS3 swap. I have a perfectly lovely straight eight out of the Packard roadster he ruined two years ago....sitting in my garage. I'll take this boat-anchor six and store it out there too...when the time comes.
***This arrangement looks NOTHING like anything from a mustang... Flapper, spring, and Sheetmetal box up around the carb. It actually looks homemade.....it belongs with the oil bath air cleaners and swamp cooler A/C. Fred Flintstone tech.

[Y33TREKker]

***This arrangement looks NOTHING like anything from a mustang... Flapper, spring, and Sheetmetal box up around the carb. It actually looks homemade.....it belongs with the oil bath air cleaners and swamp cooler A/C. Fred Flintstone tech.
I only said the setup you were describing seemed to operate in a similar way to the fuel intake choke on that Mustang. There were also metal flex tubes that ran from both exhaust manifolds up to snorkles coming out of both sides of the air intake cleaner assembly. There were valves in each snorkle that were vacuum operated rather than bimetal spring operated, but since that vacuum source came from a portion of the carb where the startup vacuum was determined by the position of a flap over the front two barrels (controlled by a bimetal choke spring), the overall intent was pretty much the same.

Glad you found the specific information you were looking for. Hey bigblock, any chance you have any similar write-ups that would explain how some of those structures were built way back when that they've showed on Ancient Aliens? ;)

[bigblock8396375]

Funny you should ask,Y33. I do have the blueprints for those structures,but I'm having trouble deciphering them. They are in ancient alien hieroglyphics!!

[blacksambo]

Ancient Porsches had the same idea. Hot air off the exhaust was blown at the carb intake. Supposedly far better than a mechanical choke which you invariably forget to turn off soon enough and cause richness damage to things below.