[my65]

Hi All,

I have a 65 coupe w/ 289 2V, with AT and automatic choke.
Questions is: The upgrade to 360 degree inlet air filter (K&N), what should I do with the warm air duct coming from the right-side exhaust manifold?

If not mistaken, this duct is usually used to send warm air to the carb. and auto-choke, to tell the choke when it is time to shut itself off.

I have made the air cleaner upgrade, and car keeps high idle much longer when compared to stock air cleaner w/ duct hooked to air cleaner air intake nozzle.

Thanks in advance for your feedback and help!

[Jeff65]

Originally posted by my65
Hi All,

I have a 65 coupe w/ 289 2V, with AT and automatic choke.
Questions is: The upgrade to 360 degree inlet air filter (K&N), what should I do with the warm air duct coming from the right-side exhaust manifold?

Mine doesn't have a snorkel so I'm gonna tell you want the snorkel does: The snorkel ducts warm air into the carb under conditions defined by engine vaccuum and a heat sensor. Here's how it works: there's a vaccuum motor that controls a butterfly in the snorkel. When the engine is cold, the butterfly is tilted to favor air inlet across the exhaust manifold. As the engine warms up, a vaccuum switch located on the intake manifold switches when the coolant temperature gets hot. Intake vaccuum via a line from the carb passes through the switch and cause the vaccuum motor and hence the butterfly in the snorkel to open allowing cold air into the carb. Warm air is better for atomization of fuel during cold starts and engine warm up. Cold air being denser than warm air produces more power hence it is used once the engine warms up.

If not mistaken, this duct is usually used to send warm air to the carb. and auto-choke, to tell the choke when it is time to shut itself off.

The carb choke thermocouple is a bimetallic that expands when heated. A small tube from the exhaust manifold ducts heat into the choke body and causes the bimetallic to unwind. This causes the choke butterfly to move from near closed to full open during the time the manifolds go from cool to hot.

I have made the air cleaner upgrade, and car keeps high idle much longer when compared to stock air cleaner w/ duct hooked to air cleaner air intake nozzle.

You need the tube between the exhaust manifold and the choke body to be connected else the choke won't open correctly. The fast idle linkage cam is connected to the choke linkage. When the choke is closed, the fast idle screw rests on the highest side of the cam. As the engine warms and the choke opens, the cam will step off in stages as the butterfly opens, provided you tap on the accelerator. If you don't tap on the accelerator, the fast idle screw stays stationary on the cam and until it lifts, the cam can't turn. If your new air cleaner installation can not accommodate the tube to the choke body, you'll be better off with an aftermarket carb (Edelbrock, Carter or Holley) having an electric choke body.


Thanks in advance for your feedback and help!