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sactoC10 · 05-14-2004, 12:43 AM

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

454_72_4X4 · 05-14-2004, 01:49 AM

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.

JimKshortstep4x4 · 05-14-2004, 08:08 AM

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

Dean · 05-14-2004, 08:16 AM

I use them. They help in the cold winter months. I guess it depends on where you live and when you drive your truck.

sactoC10 · 05-14-2004, 10:18 AM

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.

Timmerduder · 05-14-2004, 12:20 PM

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

05-14-2004, 12:43 AM	#1
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,055	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 Attached Images

05-14-2004, 01:49 AM	#2
454_72_4X4 Registered User Join Date: Apr 2004 Location: N.E. MO Posts: 1,749	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. __________________ 72 C20 4X4 454 4 speed 89 Trans Am (was) 305 TPI 700r4 93 C1500 2wd Extended cab 350 700r4 98 Sonoma (TPI outa the Trans Am) 03 Yamaha 660 Raptor 03/04 660 Raptor 07 700 Raptor 85 Honda Odyssey

05-14-2004, 12:20 PM	#6
Timmerduder Registered User Join Date: Aug 2003 Location: Oregon Washington Posts: 30	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

05-14-2004, 08:08 AM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	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

05-14-2004, 08:16 AM	#4
Dean Senior Member Join Date: Jan 2000 Location: Cincinnati, Ohio Posts: 1,492	I use them. They help in the cold winter months. I guess it depends on where you live and when you drive your truck.

05-14-2004, 10:18 AM	#5
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,055	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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