scyzoryk23

I just got 1981 vette. I will be replacing old 350 with build 355 (+new intake + new carb).

I don't have to pass emissions where I live so I wanted to remove all the unnecessary crap. So what I can remove?

Other question is…since I am replacing the engine and/intake/carb and distributor to control vacuum and mechanical advance. Can I remove stock computer (And if yes whet goes out with it...location of the computer/wires/parts that I can take out.)
S.
Ps. What else I can remove from my car (engine bay or inside)…any harnesses?

Tim81

The computer is located in the batt. compartment against the front bulkhead. Very easy to take out, a couple connectors and thats it. The dist will also have to be change to a HEI style with a Vac canister to control the timing. Other then that I think thats it, well the wiring harness if you are going to go that route too. Good Luck

scyzoryk23

So basically computer controls only timing/fuel and if removed it wont mess with any other equipment like : vacuum pumps for headlights/radio etc?

S.
ps. What about emissions? can I remove all of it?

LannyL81

The computer only controls idle mixture and spark advance. Like was said you will have to replace the distributor with an HEI vacuum advance type...about $100. Also need to replace the carb with a non computer controlled type. Either an older QJet or just about anything will work. Just do not go too big as you do not need it.

Oh and get rid of the factory exhaust manifolds...the AIR tubes stick well into the middle of the port. Lose the cat too.

The thermostat housing should just be replaced to get rid of those ugly things sticking out.

SIXFOOTER

TC lockup is controlled by the CCC system if you have an auto.
Virtually all the emisions could come off but I recommmend leaving the evap canister in place and working, all it does is collect gas fumes from the carb and fuel tank and store them until the next start and it does not use any HP.

scyzoryk23

My car has t56 transmission.
Engine: build 355 (~380RWHP)
Intake: Air gap
Carb: Street avenger 670
S.

sakins.02vert

A 76 L-82 doesnt have any emission or computer stuff right?

81pilot

You can remove the smog pump, catylitic converter, all of the plugs going into the thermostat housing can go away and you can put another on without all of that crap (leave the canister it is not a bad thing and keeps you from smelling gas fumes). I also removed my EGR stuff. As far as the computer, it controls the dist, carb and lockup on the converter so you don't need to worry with the T56. The wiring for the CCC has plugs in the engine compartment up front if you would rather leave it incase you sell is, thats what I did, you can still remove the rest of the harness and wires from under the hood that way. The stock exhaust manifolds have the heat risers out of them and they are plummed to the smog pump, so if I were you and changing engines I would go with headers and true duals like I did. It cleaned it up a bunch and helped with performance. Have Fun!

81pilot

No on computer, yes on emissions stuff to a point....81 was the first year for a computer.

sakins.02vert

Great, thanks

scyzoryk23

I will be running long tube headers with true duals chambered exhaust.
S.
Ps. Thanks for help.

81pilot

That is exactly what I have on mine. Long tubes and 2.5 inch all the way back,18 inch chambers, it sounds great!

scyzoryk23

Ok. So I started to remove parts of my engine (new engine goes in on Sunday), but there is too much stuff (all those connectors and vacuum lines). I don't really know what I have to keep and what I can remove.
I want to remove ALL emission equipment, hoses etc as well as computer controlled stuff.
My setup new 670 holley street avenger carb, new HEI with vacuum advance, new air gap intake etc etc.
Any photos of diagrams would really help me.
Thanks.

81pilot

The harness for all of the computer stuff will all go away. All of that is connected by the firewall with two large flat connectors that you can unplug, they go to the carb, distributor and sensors on the thermostat housing and an oxygen sensor in the manifold. All of the plugs to the thermostat housing are to the computer. The air gap most likely won't have an EGR so all the connectors, wiring and vacuum line to the EGR can go. The new Holley will have far fewer vacuum ports, one will need to go to the vacuum advance(non ported), a large one on the front low to the PCV valve system. It will T into the charcoal canister, I suggest keeping the canister to keep gas fumes down...With the new engine you will see what is not needed. Other vacuum lines that will allow use of the other various vacuum assisted accessories, such as the headlights and heater/AC controls. Another large vaccuum source at the base of the carb rear goes to the brake booster, it is real obvious. Be sure to wire in a way to control the torque converter lockup as well. The computer controlled part of that wires into an area on the firewall just in front of the driver.

scyzoryk23

Charcoal canister is going out. It has huge hole in it and I am not replacing it. I will just attach small filter to the end of the fuel tank line.
I reviewed some of diagrams that I found, and vacuum wise I am pretty sure what to remove, and what to keep.
As for computer wires. You mention that I can remove those two connectors on firewall, so both of them deal JUST with computer stuff? (AC/lamps/wipers and other accessories aren't related to those connectors?)


Also...what is that sensor is on the bottom photo. Is it oil pressure sensor?


Thanks.

81pilot

Yes that is the oil pressure sensor. and in your pic I can see one flat connector already disconnected and the other is on the left, those are the two I speak of. One more glaring thing to me. On The L81 motor with stock heads the valve covers bolt on in 4 places on the edge. Yours are center mount covers, ie different heads. I noticed your valve covers were different than mine when it was stock, and unless someone else tells you different, I would suspect that is not the original engine or at least not the original heads. I hope someone else chimes in....

snoopykissedlucy

Sorry for the bad news but I agree, those are center bolt valve covers AND you have a long water pump.......indication that someone stuck a non-Corvette small block with a long water pump(none came with a long water pump). This also means that all the pulleys will be wrong.

The good news, you can yank the computer and still run what you have.....unless you want to go back to Corvette pulleys......then you'll need to change the water pump to a short one and get correct pulleys. Here's a pic of my 1981 with the correct pump and pulleys.

scyzoryk23

I know about the engine. The car was purchased by previous owner as a roller. He put newer 1991 roller 305 engine out of Caprice + t56 tranny, change the v-belt to serpent system and add electric fan. Everything works just fine, but since I have this 400HP 355vci engine I will stick it in my vette and keep long water pump and the the belt system.
S.

81pilot

So he stuck a 91 motor in and used the computer from the original 81? I bet it was not working very good. I am not surprised things are not going where they should. I dont even see the smog harness, there are a lot of wires on a working CCC system that go to the front.truly, lets simplify it.... Put the new motor in, hook up what it needs to run(with accessories etc) scrap the rest, it really is just that simple.

Vetteran'81

On my modified '81 I am not using the computer either. Yet there is still one green wire coming from some sort of sending unit on the thermostat housing. I thought it was to the temp gauge or something. What else if anything might this be used for? I have a seperate sending unit next to the therm housing for my electric fans, so that's not it.

It IS ugly. I've shyed away from removing it for fear of what is could be doing. Now I am wondering, can I just pull this housing and replace it with something nicer looking? Everything else is aluminum. This is a rusty/black chunk of cast iron with a big wire coming out the top.