Heat Riser modification?

[sdkar]

Hey guys,

I have a stock 350/300hp in my 69 Camaro with the factory exhaust system.  On the passenger side there is a heat riser with a little flap inside.  How much does this affect the exhuast and more importantly, performance of the engine.  Though I would like to keep my engine compartment stock looking, would it beenfit me to remove this flap entirely?  Would the benefit be noticed or is any gain made really not worth it?

Thanks,

Steve

[L78 steve]

Its there to improve drive ability during warm up. Unless your racing I would leave it. In this case you would have headers anyway.

[rich69rs]

Personally - I'd get rid of the thing.  The ones available today tend to stick.

Might find the follwoing informative:  

http://www.camaros.org/forum/index.php?topic=9159.0

[69pace]

Do you still have the original intake manifold with the "Hot-Slot" feature still intact?
Do you start the vehicle in cold weather? 
If so you might want to keep the system intact to avoid hard winter starting, so the divorced choke gets heated nicely.
If everything is working as designed it will open allowing pass side exhaust to flow out tot he tail only once operating temp is reached.
It closes to allow exhaust to back-flow through the manifold under the Rochester Q-Jet and choke to  prevent carb icing.
Just make sure you are using the correct heat shield under the carb base on top of the fiber gasket that has the slot punched out to match the Hot-Slot.

It was a common old school fix to remove the flap and use plugs or weld shut the two ports in the Hot-Slot to prevent carb failures.
This was a major GM recall but many survive in the wild today. 

[sdkar]

I brought this up because the coil spring on my heat riser broke and I was unsure if it was worth fixing.  I can see now that it is there for a good enough reason and will just buy a new one as opposed to gutting mine.  Here is the old discussion on the "Hot Slot".  Well, it all makes sense now.  So, I guess I will replace the heat riser since the rest of the system is still there and intact.

http://www.camaros.org/forum/index.php?topic=9142.0