CXarb
Racer
Joined: Jul 2013
Posts: 307
Likes: 19
From: Kirkland WA
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,334
From: North of Toronto - Ontario
Assuming a qjet, doesn't the 68 BB have the hot slot on the intake? There was the thin metal shim to help transfer the pre-heat to the front of the carb (Felpro 60731)
Lars added another gasket to the 2 stock ones to provide a better seal between the shim and the qjet to seal better
Felpro 60043 (bottom), Felpro 60731 shim, Mr.Gasket 4256G (top)
M
Lars added another gasket to the 2 stock ones to provide a better seal between the shim and the qjet to seal better
Felpro 60043 (bottom), Felpro 60731 shim, Mr.Gasket 4256G (top)
M
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
Assuming a qjet, doesn't the 68 BB have the hot slot on the intake? There was the thin metal shim to help transfer the pre-heat to the front of the carb (Felpro 60731)
Lars added another gasket to the 2 stock ones to provide a better seal between the shim and the qjet to seal better
Felpro 60043 (bottom), Felpro 60731 shim, Mr.Gasket 4256G (top)
M
Lars added another gasket to the 2 stock ones to provide a better seal between the shim and the qjet to seal better
Felpro 60043 (bottom), Felpro 60731 shim, Mr.Gasket 4256G (top)
M
Q-Jet Carb Base Gasket Tech Info: The "Hot Slot" Manifold Problem
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
Another popular way to solve this carb heat problem is to thread the two exhaust holes in the "smile" on the intake and install a couple of pipe plugs but a gasket on BOTH sides of the heat shield is the best way to prevent vacuum leaks. If you forget the metal shield you will know it pretty quickly as the engine will barely run due to exhaust gasses being sucked in through the base of the carb.
Last edited by CanadaGrant; Jan 26, 2016 at 10:56 PM.
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Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
Another problem is if you try and use a later carb on your original "smiley" manifold. The base plates are slightly different and you will get a big vacuum leak between the front of the carb and the front edge of the "smile" on the intake. The later carb base plate does not completely cover the intake heat passage.
