Riceater

Are there any issues with disconnecting the O2 sensor when installing headers :confused Would it be best to swap out carbs at the same time

jaybird81

I don't know if this helps but I put true duals on my 81 but stayed with the manifolds. I got rid of the air pump and am in the process of getting rid of the computer controled carb in replace of a stock rochester. I also have to change the distributor because that is controlled by the computer too. so if you change the carb just keep in mind it may be a project that snowballs.

Riceater

I'm with you. The air pump is removed, as is the AC compressor. The rest of the AC is coming out soon enough. I've also disconnected teh wires going to teh egr valve and the wires that go into the front of the carb. The wire going to the top of the carb is still connected tho. Sometimes the temp sensor for the computer gets disconected, sometimes not, depending on who it is running that day.

My goal is to dump the computer in the trash.

page62

In order to dump the computer in the trash, the carb will also have to go in the trash. It has a computer-controlled mixture system.

Riceater

Right.

But, will the carb work ok if i disconnect the O2 sensor, or do i need to replace the carb when i disconnect the O2 sensor to install the headers. :confused: I wonder if that would effect teh distributor too

That brings up anouther interesting question. The tourqe conveter's lock up is controlled by the computer via a sensor behind the speedo, what happens if i dissconnect that?

BSeery

The carb will not work "correctly" without the O2 sensor. The car should run, but probably run rich.

Also, the computer may control transmission lockup on the 1981, so remember that as well.

Or does the 1981 have the vacuum switch on the firewall that controls lockup? My 1980 has the vacuum switch, but I have not seen a 1981 under the hood.

Riceater

Read the end of the post above yours on the torque lock up. :D

Yep, its computer controlled. Sounds like i will need to add a carb then. :smash:

stickboy

If you want to get rid of the 02 sensor you need to get rid of the whole system. you can move the 02 sensor to after the headers, but I believe you will need to get a heated 02 sensor, which is no big deal. :cheers:

BSeery

You can make the converter lockup with pieces from a 1980 then, if you remove the computer. You will just need the vacuum switch and do a little wiring work.
Yes, you will need a new carb and distributor if you ditch the computer.

tersian

No need to use 80' parts, just wire 12V to a switch and do the lock up manually. I only use mine when I am on the highway anyway. Just remember to turn it off before coming to a stop. :)

VegasJen

here we go again with people throwing perfectly good parts away :rolleyes:
if you insist on discarding the O2 sensor then neither the carb nor the distributor will work correctly. screw the EGR, who cares about that. but if there is nothing wrong with the operation of the computer as it is, why not just get a set of headers with an O2 port? either that or have one welded in like i did.
different cam, heads, exhaust and the car makes a legit 240hp and runs just fine. could probably go higher without problems if i had the money.

UKPaul

I'm with Clutchdust on this one. I've got Headers & true duals with... I'll attach my sig!!! I got a pair of reducers from Summit that fit my Dynomax Headers that have provisions for an O2 sensor. I had to buy a pair of normal reducers & a pair of the ones for the O2 fitting (they only come as pairs). All I've got left from the stock setup is the carb, computer & dist. The TCC lockup I had to change as I fitted a TH200-4r & the computer control of lockup didn't work. There's a simple frig of the wires in the engine compartment that will bypass the computer for lockup & retain the feature of the brake pedal unlocking the converter. If you do remove the computer IM/email me & I can send you details of how I bodged it up & how to add a manual switch for lockup (or you could go the vacuum route).
The great thing with keeping the computer is that it will automatically adjust the carb to compensate for the better exhaust system. This doesn't apply to the secondaries (which work the same as a non-computer Q-jet). I'm starting to suspect that my secondaries are running very slightly lean, but as I cant find any rods/hangers here I can't play around with it to verify that.
Bottom line is that my Vette has much more ooomph than it did as stock &, get this, last weekend I calculated that on a long run I was getting 27mpg!!! Yeah baby, yeah!!!
If you keep the computer and get the reducers with O2 fitting then you've just got to spend $30 or whatever they were. If you buy a new carb, etc you'll be spending a little bit more :)
:cheers:
edit: If you just disconnect the O2 sensor then the system will go into open loop where the carb will run very rich. Power will be down, the Check Engine will show an error, it'll run like a pig,etc, etc. I think it'll be fine at WOT though!!! The O2 sensor is crucial for the computer to work correctly.


[Modified by UKPaul, 4:18 AM 8/15/2003]

Riceater

Thanks for the info. I sleep on what i want to do, but i'm leaning towards new carb/distributor to go with the headers.

adam

Hey Paul;

Which reducer did you use - Got a part number or something?
I was looking at two different reducers. The standard ones that reduce in about
an inch or two. There is also one that does it in about 6 inches. Wondering what's
best...

I'd stick with the same carb and dist and put in the O2 sensor! Definitely cheaper
and I doubt you will gain a lot by going to another carb/dist.

:cheers: :blueangel:

page62

Don't be so sure on the carb/dist swap! I helped a friend swap an intake, carb, and distributor on his '81. It was an Edelbrock Performer intake, a Holley 750 vac. sec. carb, and an Accel HEI distributor.

That guy is now one of the happiest Vette owners I know!!! :steering:

UKPaul

But Page, you know me & I'm happy :lol: :D

Adam, the reducers are 3" to 2 1/2" & the part number is wlk-88314. They are the same length & design as the stock ones that came with the Headers (which reduce in an inch or 2 & are probably about 5" in length overall, at a guess). Cost was $31-99 in the US & I'm sure that they came from Summit.
All they are is the stock reducer with a hole drilled through it & a round nut welded on the outside over the hole. From memory (which is so bad that I never rely on it!) the thread on the O2 sensor is M18 with a 2.5 pitch.
:cheers:

Riceater

Hey Clutchdust, you need an extra O2 Sensor. :D

Ordered some Dynomax ceramic headers today, along with a Road Deamon, Distributr and RPM Air gap