2885-12

what do i do with the tubes going into the manifolds on both sides.the car running is making noise thru these tubs that the smog pump had hoses connected to

moosie982

Go to Lowes, Home Depot or your local Hardware store & buy some pipe plugs, off hand I cant recall the size, Peace,,, moosie

Steve2147

After you remove the pipes, and before you put theplugs in you have to remove the short tubes that are sitting inside the holes. They are about 3" long and just sit in the holes. You can get them out by threading a self tapping bolt into them and pull them out. I've never seen it happen, but apparently without air running through them they will get very hot and droop into the exhaust manifold.

Steve g

mapman

Welcome to the Forum!

Make sure you get PIPE plugs (tapered thread). You might save the removed parts, never know when you might need them some day.

After you remove the tubing. and BEFORE you cap the holes with the pipe plugs, you need to remove the inserts (tubes) that are inside the exhaust manifold.

I found it easiest to remove the inserts by making a simple tool from a wire clothes hanger. Get a fairly stout hanger and bend a short section the wire 90 degrees. Clip off MOST of the short bend section - what you want is a kind of "hook" on the end of the wire. The "hook" has to be small enough to fit into the hole of the tube. Feed the wire in and the "hook" will catch then end of the plug - then just pull the tube out. (Easier to do than to write!)

Again, welcome to the Forum.

80Baby

You removed the A.I.R. pump? Good for you. They're the bane of all C3's.

2885-12

dont want to sound stupit but are the tubes the small ones that are going into the manifold there are four coming from a large one that had a hose on it from the smog pump.do these four small have to be cut off.can i just cap the larger one that they connect to thanks again

2885-12

do the four small tubes that are going into the manifold on both sides need to br cut off.they come from the large tube that had a fitting with a hose on it that went to the smog pump.thanks again. if i have to remove them do i have to cap all the holes

Mike Ward

Ya, the 1 HP the pump uses really kills performance.

terry82

i would leave the four small tubes in the header.then just cap the hose end .if you have the factory shorty header the little tubes are hard to close off .the header is stainless.they are hard to weld on .you can cut the tube 1/4-1/2 inch up then pinch off with a pair of vise grips .or just leave on and plug all with one round plug in the hose.

bschuus

What do these "tubes" look like when your looking in hole with a mirror after the flare fittings are removed? and will they truelly melt.

maxmachz

You guys lost me here...you are pulling the pipes out of the manifold and putting four plugs in per side? You can just pull these out?



Scenario: if you do have the A.I.R. pump, and it has ceased to function and you did not know, these pipes would melt / droop? From what I have read in the service manual, the pump only pumps air under certain conditions, not all the time, so this should not be an issue?

Steve2147

Sorry, I thought the op's car still had the cast iron exhaust manifolds. For the factory headers I wouldn't worry about it.

But I have to agree with Mike, lot of work for a negligible increase in power. Kinda like reducing the weight by emptying the ashtray.

Steve g

MYBELLA

I was thinking about taking my air pump out this winter on my 81. Is it going to cause problems with the computer?

maxmachz

No. ECM does not have any inputs from that, or the cat converter. The ECM does output to the pump, but does not know it is not there nor cares. Some say it will alter the exhaust enough to make the O2 sensor read out of spec but I have not seen that.

From the service manual:

Pump puts air into the manifolds when the engine is cold, for control of HC and CO, and to help warm the cat; when engine is hot, it puts air into the cat to help it's performance. On deceleration and wide open throttle it puts air into the air cleaner.

You'll see the pump has four out puts, one for each manifold, one to the cat, one into the air cleaner. It also has a vac line from the EFE (Early fuel evaporation) TVS (Thermal vac switch) going to the the EFE valve on the right exhaust header. Just plug the line going to the pump so the EFE works right when the EFE TVS tells it to. Other wise you will have a vac leak and the EFE will not function.

Hope this helps.

rdroe

Before I put a modified manifold on, I just capped the large tube coming from the pump. I bought a new *set* of exhaust manifolds from eBay for a steal that the owner went through the trouble of brazing the little holes shut. Factory exhausts are really good with power! Not really a compelling event for headers right now in my world thanks to them. Don't forget the port leading to the cat.

stevelischynsky

If you send me all these parts, I'll pay for the shipping. Then I'll sell them back to you in a few yrs for around $1000, when the EPA Gestapo gets after you or you want to sell the car "complete". That way you won't lose them. They are numbers and date matching.

Steve L
73 coupe since new

Mike Ward

I'm always amazed by the big rush to remove smog pumps or other innocuous bits of smog gear and the variety of excuses as to why it 'needs' to be done.

commander_47

Air pump contributes almost nothing to cleaning up the environment.

Yet, like a huge wart, it hangs there in the engine compartment.

All of the smog bits on the 81 contribute almost nothing to cleaning the air but collectively suck the life out of the motor.

rdroe

And make the engine compartment *ugly as sin* ! If you don't care about that part of the Vette, leave it there. For me, one of the many parts of the car that I pay major attention to is the engine bay.

Mike Ward

Yup there's the top three 'excuses' right there.