Originally posted by b4black
Are we talking about the same thing? I always knew a "heatriser" to be the butterfly EFE valve in the exhaust maniofld which redirects exhaust gases thru the intake manifold. This EFE valve was replaced by the electric EFE (heated gasket). The "heatriser tube" Jim was referring to is for THERMAC air cleaner.
The THERMAC tries to maintain the incoming air at 115°F. Without it, I notice bogging when the ambient air is below 50°F, even when the engine is at operating temp. It seems the EFE and THERMAC do the same job, heating the incoming air. The EFE heats up quickly for cold-start conditions and then turns off. The THERMAC doesn't work immediately, but continues after the EFE has turned off.
BUICK83-T, whats your outside air temp like where you live?