[parsival]

Hi, After a long search I finally found a 1970 and up dual snorkle air cleaner for my 69 GTO. It's the best thing I can find here. It needs a re-paint end re-chrome but the rest looks good.

I wonder what the valves in the ducts are for and where do I connect the two hoses attached to them ??

Thans,
Arno

[Overkillphil]

They are part of the cold start (aka fast warm up) system. A aluminum flex hose connects them to the heat shield on the exhaust manifolds. When cold, the flaps close, forcing air to be drawn up around the outside of the exh. manifolds (they are first to get hot) and through the tinwork, up the flex hose and into the air cleaner.

A vacuum hose connects the flap to a thermal switch on the intake. When the thermal switch is satisfied (coolant sufficiently warm) it opens the flaps and air is drawn through the snorkels in normal fashion.

[70pontiaction]

On my 69s and 70s the thermal switch is located right on the bottom of the air cleaner and measures the air temp around the top of the carburetor, so it senses when the carb is warm enough to idle properly. The vacuum hose that feeds the switch goes directly to manifold vacuum at the small vertical fitting right in front of the carburetor.

The vacuum switch on the intake manifold water crossover turns the vacuum advance on and off depending on coolant temperature. I'm pretty sure it turns the advance on fully when either really cold or really hot (too hot) and ports it in between (normal operating temps).

[parsival]

Thanks guy's. I only drive the car in the summer so i'm not going to connect the vacuum doors.

[bobunit9]

Originally Posted by Overkillphil

They are part of the cold start (aka fast warm up) system. A aluminum flex hose connects them to the heat shield on the exhaust manifolds. When cold, the flaps close, forcing air to be drawn up around the outside of the exh. manifolds (they are first to get hot) and through the tinwork, up the flex hose and into the air cleaner.

A vacuum hose connects the flap to a thermal switch on the intake. When the thermal switch is satisfied (coolant sufficiently warm) it opens the flaps and air is drawn through the snorkels in normal fashion.

Can this type of air cleaner be used without the heat riser tube (got headers) and still function properly?

[rolling money pits]

Originally Posted by bobunit9

Can this type of air cleaner be used without the heat riser tube (got headers) and still function properly?

what do you mean by function properly, able to ingest air at all, or utilize the cold start part of it?

the flappers in the snorkles are defaulted to being open, no vacuum applied, theyre open. when vacuum is applied they close off directing it from the exhaust manifold heat shield. on dual snorkle air cleaners originally on ram air ( IV at least, possibly III ) cars both snorkles had provisions for preheated air. non ram air cars had only one, the drivers side. if vacuum is applied under that type the passenger side is blocked and air can only come from the drivers side snorkle. so yes, they will work w/o a preheater tube, but you either want no vacuum at all going to the flapper motors or a functioning thermac switch in the air cleaner.

if you mean working as in using the preheat function on cars with header, they will also work. the factory heat shield on the head studs would work. if you dont have one hedman i think makes a gizmo you clamp around one of the tubes and attach the preheat tube to it. that might pose a problem on pontiacs due to the head design and header routing. i dont see why a factory one wouldnt work though, heck, you could poprivet on some extensions just to be safe.

[bobunit9]

Originally Posted by rolling money pits

what do you mean by function properly, able to ingest air at all, or utilize the cold start part of it?

the flappers in the snorkles are defaulted to being open, no vacuum applied, theyre open. when vacuum is applied they close off directing it from the exhaust manifold heat shield. on dual snorkle air cleaners originally on ram air ( IV at least, possibly III ) cars both snorkles had provisions for preheated air. non ram air cars had only one, the drivers side. if vacuum is applied under that type the passenger side is blocked and air can only come from the drivers side snorkle. so yes, they will work w/o a preheater tube, but you either want no vacuum at all going to the flapper motors or a functioning thermac switch in the air cleaner.

if you mean working as in using the preheat function on cars with header, they will also work. the factory heat shield on the head studs would work. if you dont have one hedman i think makes a gizmo you clamp around one of the tubes and attach the preheat tube to it. that might pose a problem on pontiacs due to the head design and header routing. i dont see why a factory one wouldnt work though, heck, you could poprivet on some extensions just to be safe.

That's what I needed to know. Thank you.