I have an exhaust leak where the butterfly valve rod comes through the manifold.
Is this normal? It is wiggly and loose. For a lot of years I assumed the exhaust leak was coming from between the block and and manifold.
What are my options to eliminate this small by annoying exhaust leak? I don’t want to go with a dual exhaust setup because I want to preserve the origin looked of the Thriftmaster.
Last edited by ChevyDarren; 04/18/20219:29 PM.
Darren Current Project - 1950 3100 5 Window with a rebuilt 216 and 3 speed trans
Easier said than done. I suspect you would have to remove the manifold from the engine to remove the heat riser shaft. The valve or flapper could be rusted solid to the shaft. BTW, the orientation of the valve in the picture may not be correct so don't use it as a reference.
The over-sized shaft has this note: NOTE! This item is not available now, however we are accepting names to add to a list to be notified when we can get or produce this item. My take on this is that they need several orders before having some made. I would call and ask.
I wasn't able to find the bushings in the Chevy Master Parts List but with a little research on the Internet, you should be able to find what you need from a bushing supplier.
When the valve is closed, I suspect you have exhaust backpressure hence the most noise. Is the noise that bad when the valve is open?
If this is a car/truck residing in the warm state of California, you may not need a heated manifold. A person could fix the valve to remain open and pack the gap around the shaft. Just a thought.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
I don’t know we’re you would get bushings from but maybe a bushing from a door pin can be matched up. Here is what I found on a broken manifold that I kept the heat riser
Found mine at Ace Hardware but that was about 7 years ago....I also made my rod from a piece of rod stock and then using my dremel cut the slot....and had a friend to tack the butterfly with a welder. It takes a little time but well worth the effort.
...you may find when you get it apart that the "slop" in it is caused due to the bushing worn out on one side. Just be sure to make the positions as you take it apart... even draw you a picture! Let us know how you do.
Too bad I’m not in Fresno anymore to help you. One of my bushings was completely worn through, other leaking. I remade a stock size stainless shaft. With lathe turned stainless bushings and drilled manifold for thicker bushings. Maybe you or friend has lathe?
I cut a new shaft from some stock stainless steel rod slightly oversized, drilled the cast to fit for easy but tight movement, ran the bit through the flap, hacksawed a slot in the rod for the thermal spring, drilled and tapped the flap and rod for a small stainless screw and peened the end after put in place. i added a little more length to the slot end of the rod to not need a spring retainer.
Larry Old man᠁Old truck᠁neither one goes very fast. All you need in life is TIME, PATIENCE and MONEY. If you are missing one component, you'll need an abundance of the others two.
