What is this and do I need it?

[skokie]

Circled in blue.

[sjarrett71]

That looks like a heat riser and I've never seen one that was in working condition. Most of them were wired open.

[The Hard Way]

That's a heat riser. It helps your truck warm up faster. If it's working well and you live in a cold area it might be easier to leave it in, but obviously they're obsolete since vehicles haven't used them in ages.

[C10-Driver]

That looks like a heat riser valve (not sure of the correct term). It closes when the vehicle is cold so that warm air is forced up through the riser into the air cleaner and carb. I would say it isn't required but may help your truck run better when it is cold outside. If you aren't running a factory style air cleaner, it probably isn't serving any purpose whatsoever.

I'm not bad with mechanics but you should probably wait for another, more knowledgable board member to confirm.

[skokie]

Sounds like I wont be needing it. The exhaust manifolds are coming off to get blasted and painted. It will be heading to the garbage can.

Thanks

[wheels67]

I know somebody will "Pipe" up .......get it, PIPE up.
My uneducated guess is its a vavle to help your truck warm up faster by closing the exhaust tube until temp is reached. You may not need it if you live in a warm area or have no emmision laws.

[Luvlegs]

it restricts the exhaust flow until the engine heats up - like a mechanical choke - at least that's what I've always been led to believe. On all the old cars I had as a kid, that was one of the first things we took off. Then again, we also put on dual exhausts with no cross overs either. If they get too rusty they might stick in the partially closed position. That's about all I can tell you.

[Draggn66]

Yes that is a heat riser and you can just leave it off after you remove and paint your manifolds but.....remember unless you are putting new pipes on as well that manifold will be a bit shorter with that riser removed. Maybe your exhaust pipe will still reach but maybe it won't. Don't ask how I know

[GREASEMONKEY72]

[Longhorn Man]

but don't throw it away. With the constant threat of Cali goin back to the old emission laws and testing procedures... you may need it one day.

[Blazer1970]

What that does is forces the exhaust to go through the crossover in the intake manifold to the exhaust manifold on the opposite side. This warms the carb and also heats the choke coil spring so that the choke opens properly. That set-up really improves driveability in cold weather.

[OhNoJoe]

If your throwing it out. I'll take it off your hands for a reasonable price

[skokie]

Andy I hope not. If I have to get a A.I.R system together then I am screwed. I have only seen 1 of those in the last 2 years. OhNoJoe I am not sure I am going to be getting rid of it here shortly until I know that I wont have to get a longer pipe put on.

[1LoC10]

mine was wired open when I bought it

[PumiceMan]

The exhaust on my camaro still has the outside shell, but the flapper had been pulled out of it and the small hole in the sides (where it pivoted) welded up. I assume this was done so the pipes would still fit without modification, and there's less restriction without the flapper in it at all (as oppossed to wiring it open, or removing the spring).

I've since seen than you can buy a spacer and just replace the whole riser - I think there's only 2 sizes, small block and big block. I probably saw them in a camaro parts book - Year One, Classic Industries, Rick's First Gen, something like that. I think they were around $25. The spacers are sometimes called "riser eliminators".

Actually, I just found them in Rick's First Generation - $26.95 for SB or BB.
(Just in case anyone was interested.)

[jerry moss]

if the pipe won't fit, you can go to your local muffler shop and buy a "heatriser block". before you pitch your current heatriser make sure your manifold is machined to accept a donut gasket--not all manifolds are,some are flat.