Exhaust heat risers, yea or nay?

[ksierens]

Do most of you just weld up the heat riser holes in the exhaust manifold, or do they really help to heat up the engine?

[Burdar]

The heat riser forces more exhaust through the heat crossover under the intake manifold and into the DS exhaust.  This helps heat up the intake on cold mornings.  I'm going to guess that most aftermarket intakes don't have an exhaust passage through the intake.  The heat riser will be doing nothing if you don't have that passage.

If you are using an intake with a heat crossover and drive in cold weather, then you might consider keeping the heat riser.  With todays gas however, keeping the intake and carb cool is more important than quick engine warm up. 

On my stock manifold, the flapper broke loose from the shaft and I didn't weld it back on.  I still kept the shaft in place for a stock look on the outside. 

[Chryco Psycho]

 
I agree , in most cases it is detrimental

[RUNCHARGER]

Never a priority other than for looks.

[AAR#2]

https://forum.e-bodies.org/exhaust/17/340-exhaust-manifold-condition/5058/msg71554#msg71554

Posted up this option with photos for a stock look that appears functional and no restrictions.

[Hambone1]

So I just purchased a 1970 440 6 pack and it has been sitting for a number of years. The heat riser seems to be rusted. What are the implications of driving with it rusted shut?

[RUNCHARGER]

Not good, rusted open is okay, rusted closed will force all the exhaust up the intake manifold and out the left side. So, that would mean your 440 is only breathing through single exhaust.

[Dakota]

If it's rusted fully closed and doesn't move at all, one side of your engine is going to have a tough time exhaling and will run like crap if it runs at all.   As stated above, you're better off removing the plate.  The remaining shaft won't matter much as long as it doesn't leak where it passes through the walls of the manifold.

[Hambone1]

Yea thanks. I believe it's not fully closed but, rough.

[Chryco Psycho]

Welcome to the site Hambone !

[CudaMoparRay]

Welcome to the site Hambone !

Yes indeed, a big  from Riverside, CA