Intake question: What is this thing?

rcmaniac791

rcmaniac791

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Real quick question because I am very curious. When I replaced the carb on the 5th, I noticed this check-valve type thing in the left carb port in the intake. (see the picture I found below)

What is this for?
IMG_0928.PNG
 
I believe (if my memory serves me right) that is your EGR feed into the manifold runner. So basicaly, once your EGR valve is activated and starts re-circulating the exhaust this port in the floor will start flowing that exhaust gas into the engine.
 
It always confounded me why it was so high on passenger side of intake.
It looks more like a restrictor at first glance – and for the one side.
The only thing I can think of is there must be engineering and testing for the reason that part is so tall.
BudW
 
It's because the floor of the plenum is so high there and close to the butterfly that any upwards gas pressure from the exhaust might blow air/fuel back up into the air cleaner. That part redirects the flow into horizontal jets that shoot out all sides instead upward. The other side is much further away so it's not that important.
 
I have heard that story before.
The intake is generally under a vacuum – even when under WOT (Wide Open Throttle).
The exhaust is under some pressure – but not a lot.
The vacuum circuit of EGR valve will shut it off anytime the engine is under a load – the most exhaust pressure present will be at idle or cruising (so, not a lot of pressure).

I can see re-direction of EGR flow, but at first glance - it still looks more like a restrictor than it does anything else (note: I’m applying what comes logically in my head).
There is a reason (maybe several reasons) for doing it that way – But logically, I don’t see it.
BudW
 
That makes a lot of sense. I agree with you Bud that at first glance it looks strange, but we will just have to trust that the engineers knew what they were doing.


This is why I love this site. Lots of good knowledge and I love learning all about it.
 
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