Question About '75 Rochester Quadrajet.
Thread Starter
Racer
Joined: Sep 2001
Posts: 407
Likes: 10
From: Maryville Tennessee
Question About '75 Rochester Quadrajet.
Hello,
Did the quadrajet's that came on '75 Corvettes have the round, plastic choke assembly or the "all metal" assembly? Will either type work on a '75? Thanks for any information.
Robby
Did the quadrajet's that came on '75 Corvettes have the round, plastic choke assembly or the "all metal" assembly? Will either type work on a '75? Thanks for any information.
Robby
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Question About '75 Rochester Quadrajet. (75SHARK)
My choke housing is metal, but the "lid" used to adjust the choke setting is black plastic. I believe my carb is all original. The original choke has a heater that draws heat from the intake manifold and passes it into the choke housing...a plastic choke housing would melt or at least get brittle and break. I suggest getting the metal housing, unless you want to retrofit with an external automatic choke, or convert to manual choke.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Question About '75 Rochester Quadrajet. (75SHARK)
75 -
Rock is right: The actual housing is cast aluminum, and was a natural silver color when new (the carb itself was a goldish color from the iridite finish). The round cover on the outside of the housing that contains the bimetallic spring is made from a thermosetting hi-temp plastic compound resembling the old "bakalite." It is heat resistant and very brittle, and is naturally black in color.
There were 3 different styles of chokes used: Early cars used the "divorced choke" consisting of a bimetallic spring enclosed in a cover bolted to the manifold heat riser. This spring was connected to the carb choke mechanism via a rod.
In '75, a big, round choke housing attached the the side of the Q-Jet. Inside, was a bi-metallic spring connected to the choke mechanism. This housing was heated with metal tubes coming out of the manifold exhaust crossover, feeding hot air into the choke housing attached to the carb.
Later models used the same big round choke housing, but utilized an electrical connection to heat the bimetallic spring instead of hot air.
Rock is right: The actual housing is cast aluminum, and was a natural silver color when new (the carb itself was a goldish color from the iridite finish). The round cover on the outside of the housing that contains the bimetallic spring is made from a thermosetting hi-temp plastic compound resembling the old "bakalite." It is heat resistant and very brittle, and is naturally black in color.
There were 3 different styles of chokes used: Early cars used the "divorced choke" consisting of a bimetallic spring enclosed in a cover bolted to the manifold heat riser. This spring was connected to the carb choke mechanism via a rod.
In '75, a big, round choke housing attached the the side of the Q-Jet. Inside, was a bi-metallic spring connected to the choke mechanism. This housing was heated with metal tubes coming out of the manifold exhaust crossover, feeding hot air into the choke housing attached to the carb.
Later models used the same big round choke housing, but utilized an electrical connection to heat the bimetallic spring instead of hot air.
