The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Will these stock ex manifolds seal off without heat riser?

68c10airstream · 01-22-2016, 09:20 PM

Recall from about 30 years ago i think there is an exhaust donut for eliminating the heat riser. I believe it looks like a donut (that you eat) sliced in half and there is a metal flange that has been formed inside the throat and has 3 raised nubs that stick up and when installed the nubs grab the inside throat of the manifold and hold it in place till the exhaust pipe is installed. Obviously the drivers side gets the full height donut to fill in the recess in the manifold and leaves a raised donut to seal up against the down pipe. To sum it up when both sides are ready for a "Y" pipe to be installed BOTH sides look the same and if you didn't look close you wouldn't know the passenger side had a flat flange.

The passenger side will need shorter studs.

01-22-2016, 09:20 PM	#4
68c10airstream Registered User Join Date: Mar 2013 Location: Marquette michigan Posts: 828	Re: Will these stock ex manifolds seal off without heat riser? Recall from about 30 years ago i think there is an exhaust donut for eliminating the heat riser. I believe it looks like a donut (that you eat) sliced in half and there is a metal flange that has been formed inside the throat and has 3 raised nubs that stick up and when installed the nubs grab the inside throat of the manifold and hold it in place till the exhaust pipe is installed. Obviously the drivers side gets the full height donut to fill in the recess in the manifold and leaves a raised donut to seal up against the down pipe. To sum it up when both sides are ready for a "Y" pipe to be installed BOTH sides look the same and if you didn't look close you wouldn't know the passenger side had a flat flange. The passenger side will need shorter studs.