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Old 05-14-2004, 12:43 AM   #1
sactoC10
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What is this part?

This was on the 1970 350 I parted out, driver's side, coming off the exhaust manifold. What was it's function? Is it worth using still, or should I just add it to the parts bin for nostalgia reasons? Thanks!

Jeff
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Old 05-14-2004, 01:49 AM   #2
454_72_4X4
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That's the heat riser, (or that's what I call it anyway).
It blocks of the exhaust forcing the exhaust to got through the heat riser passage in the intake under the carb to warm up the carb faster, (or something like that).
As the spring on the side of it gets hot it opens up and lets the exhaust flow normally.

I usually just toss it unless the exhaust manifold doesn't have the angled recess for the exhaust doughnut. If the manifold surface is flat you have to use it or change manifolds. In those cases I cut out the butterfly valve and put a bolt in the hole where the shaft used to be.
I'm sure somebody else can explain how it works better than I can.
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Old 05-14-2004, 08:08 AM   #3
JimKshortstep4x4
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Smile

I toss the heat risors, also. If the manifold has the flat gasket surface, I will grind an angled recess with a die grinder for the doughnut to fit in. Works very well!

Jim
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Old 05-14-2004, 08:16 AM   #4
Dean
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I use them. They help in the cold winter months. I guess it depends on where you live and when you drive your truck.
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Old 05-14-2004, 10:18 AM   #5
sactoC10
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OK. It was already removed on my daily driver. Must have been done when the exhaust was split. I'll have to check this out to make sure everything is flush and smooth.
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Old 05-14-2004, 12:20 PM   #6
Timmerduder
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Heat riser is important

It evens the heat flow when the motor is cold... like a previous post lists, it depends on where you live and when you drive. I live in Oregon and have a 15yr daily driver that goes to the mountains almost every week and it is a MUST. You don't HAVE to have it but it does shorten the life of your motor without it.

My 2 pennies
Tim
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