Kalway

What are all the steps to making an '81 non-computerized? I wanna just make it more like an early 70's setup. Smog isn't an issue. I'll still use a quadrajet, just not the E4ME. Probably just a remanufactured quadrajet with an electric choke. I'm going to get the dual exhaust kit from midamerica eventually, also.

Pauld

I am doing just this very soon, just ordering all the parts from Summit.
You will just need a new carb and a new distributor to eliminate the computer.
My project is a little bit more involved, in that I am changing the heads, Carb, intake, camshaft and distributor. Just looking for more power. I already have the true dual exhaust system.

Kalway

What sort of distributor do I needa get? Just an early 70's HEI type? I'm eventually going to do vortec heads and intake also. Already did my camshaft

2 C-3"s

Yes any early 80 HEI will work --- I have an 81 and I replaced the following
1. New Edlbrock 600 cfm carb
2. New Edlebrock performer rpm intake
3. true duals to only monza tips
4. drop base air filter with a K/n
Just unplug the computor and remove all your smog junk off --- mine runs and sounds much better ---
If you want to hear and see how much better drop me your email address

B

2 C-3"s

Yes any early 80 HEI will work --- I have an 81 and I replaced the following
1. New Edlbrock 600 cfm carb
2. New Edlebrock performer rpm intake
3. true duals to only monza tips
4. drop base air filter with a K/n
5. New Hei distibuto from junk yard $ 15
Just unplug the computor and remove all your smog junk off --- mine runs and sounds much better ---
If you want to hear and see how much better drop me your email address

B

Kalway

What does all the smog junk consist of? I already removed the smog pump, what else is there?

2 C-3"s

From My 81 I removed the smog pump , all the tubes on the tops of the headers , the egr valve--and then just unplugged and removed the computor .

It really does run better now !
B

Kalway

Is that edelbrock similar to a quadrajet? I really want to stick with a Rochester Q-jet. I'm thinking for a quick touch up to just get a pre-E4ME Q-jet and remove all the smog crap.

Doesn't the computer control the lock up convertor for the transmission?

bobs77vet

i think 74 or 75 was the first year for the HEIs

Dalannex

The computer does control trans. lockup. The easiest way to deal with this and still have lockup would be to call bowtieoverdrives and tell them you want one of their bosch relay lockup kits. Install that and your lockup will work without the ECM.


-Justin

MsVetteMan

exactly what does the lockup do?

danno12345

From what I've gathered, the lockup locks the 2 parts of the torque converter together, giving the engine a direct drive to the rest of the transmission. This eliminates the slip inherent to automatic transmissions, and improves gas mileage and lowers heat production in the tranny.

It should only engage when the engine speed is relatively constant, like when cruising at ~40+ mph.

I believe they started showing up in 1981 with the TH350C transmission, and are pretty much standard equipment now. If you drive along in a car with a tach, you can watch it shift into overdrive, then if the speed stays more or less the same, in a few seconds the tach will drop another hundred or so RPMs. That's the lockup engaging.

Somebody please correct me if I'm wrong, cuz I'm still learning. I'm pretty sure my lockup is not functioning since my computer is disconnected. One of my plans in the future is to put in a manual switch. Of course, that may just happen in a year or 2 when I swap in a 200-4r... :P

Dan

UKPaul

Danno is correct on lockup except that it drops rpms by about 300 when locked (and it first appeared in the '80 305?). An easy way to tell if it's locking is to cruise along in drive at about 60mph & gently depress the brake pedal while keeping the throttle in the same position. The rpms should raise by about 300 & road speed stay the same (assuming the TCC brake switch is adjusted correctly - if it needs adjusting then book a Chiropractor b4 doing it or, better still, remove the drivers seat. It's only a couple of connectors & 4 bolts & will save a lot of pain & frustration. Additionally, without the seat in the way, you won't need to use your third hand!).
All the computer does is decide when lockup should occur. Not sure of the decision parameters, but they include coolant temp & maybe speed. The TH350C that was in mine had an internal pressure switch that decided whether to lock or not (even when the computer had told it to). This switch stops lockup in the low gears & at low rpms in "top" gear. Or so I was told (I never verified it as I couldn't get the darn thing to work!).
Getting lockup to work after ECU removal is simple. It all depends on how much stuff you rip out when you junk the computer (if you intend throwing it in the trash let me know as I may be interested in buying it from you). If you leave the wiring pretty much alone & keep the TCC/EGR relay (on a bracket on the d.side of the firewall) then you can hook up a switch in place of the computer. If you remove the d.side console cover & have a look at all the wires under it you should eventually find a black/tan wire that goes back to the computer. Rather than chasing it through to verify that it goes to the ECU, somewhere in the area of the ashtray you'll find a small, black plastic block in the wire. On the side of the block is a partially exposed male spade terminal. This is the TCC diagnostic test point. This wire is the one that goes to the computer to control lockup. All the computer does is to connect it to earth. This throws the TCC/EGR relay & switches 12v through the trans to lock it up.
Now, this is where a pic is better than all my ramblings, but 12v from the TCC brake switch is what passes through the relay to the black/tan wire. So for the relay to throw, the ECU must have earthed it & the TCC brake switch must be closed ie brake pedal not depressed. If this is the case, then another 12v supply that it connected to the trans, passes through the pressure switch & TCC solenoid in the trans & then goes through the relay (if thrown) where it connects to earth. If the relay is thrown then power goes through the TCC solenoid & lockup occurs (don't ask me how, I'm still having trouble getting to grips with how squirting trans fluid can transmit several hundred horses!).
Or, putting it in another confusing way, the relay is just an electrically controlled switch. One circuit turns the switch on/off & another circuit is what gets turned on off by the relay. The circuit that turns the switch on/off is the 12v from the TCC brake switch which gets earthed by the computer. The circuit that the switch turns on/off is the 12v going through the trans & out to earth.

So, if all the wiring is still in place, just take a wire from the TCC diag connector (from the spade so thoughtfully put in the connector), connect it to some sort of switch & wire the other side of the switch to earth. That should do it assuming everything worked prior to ECU removal. Before wiring up the switch it would be a good confidence check to connect a flying lead to the diag connector & get a passenger to connect it to a good earth while cruising. If it doesn't lock then there's no point in wiring the switch to it!
If it doesn't work, or you've junked the relays & wiring, then all you need to do is find the harness coming up from the TH350C. It'll be on the drivers side & comes up the firewall somewhere in the mess behind the rear of the valve cover. There will be a 4 pin connector on the end. Disconnect this from the main wiring harness as chances are it won't be doing its thing anymore. On the connector (with mine) there were 3 wires connected. The one on pin C does nothing, it's not connected in the trans (I looked). Pin A is the 12v supply to the trans & pin B is the return to earth from the trans (the one that the computer & relay tortuously connected to earth). Confused yet? If so then don't look at the connector at the trans, as pin B at the harness behind the valve cover is wired to pin D on the trans, which is just great (in fact, do not disturb the connector on the trans unless you suspect that the terminals are dirty & not making a connection. The tabs on the connector are really easy to break off, mine are in the corner of the garage. Don't say I didn't warn you )
To get it working find the 12v wire that comes from the TCC brake switch. It's the one that goes to pin C on the TCC/EGR relay on the firewall (this is also a convenient point to use an AVO to verify that the TCC brake switch is adjusted/working correctly). Cut this wire at the connector & connect it to pin A on the harness going to the trans. This will give the 12v supply for lockup & also ensure that it unlocks when the brake is pressed. The other pin on the TCC harness, pin B (or D as it's labelled on the trans itself ) needs to be taken inside the car & connected to a switch of some sort. Connect the other side of the switch to earth & you'll have lockup when you throw the switch. With the switch thrown, pressing the brake pedal will unlock the converter.
Rather than running new wires through the firewall you can use one of the old ones. An ideal one would be the black/tan one that has the TCC diag connector on it. This wire goes to pin B on the TCC/EGR relay connector. So cut it off & connect to the TCC harness connector.
This mod worked on mine. My lockup just stopped working. I had my passenger connecting wires to live & earth at 70mph, there were wires snaking their way into the engine bay & under the car to the trans & TCC wouldn't lock. Problem was in the trans. Replacing the pressure switch & solenoid didn't help so I gave up & fitted a th200-4r Altering the wiring so that the new converter would be locked by the computer didn't lock it Earthing the TCC diag connecter manually did lock it (my passenger is getting good at electrics!). I've since found out that the computer can refuse to lock the converter if it doesn't think that the coolant is hot enough. My TCC lockup failed sometime after fitting a 180 stat...... which pretty obvious when you know about it So, any TCC lockup problems on computer controlled L81's could be due to a bad ECU coolant sensor, or an efficient cooling system with a lower temp stat. To have the trans fail at the same time is just sh1tty luck & I've since found a clogged passage in the old TH350C, which proves that my luck is holding If you remove the TCC solenoid (just 2 bolts) & something else behind it (dunno what it's called auto trans are a total mystery to me) then look up inside, you may find that one of the small passages is clogged with fine silver/gray gunge. It's obvious when the trans is on a bench, but is very hard to find when lying under the car with trans fluid dripping in your eyes, up you nostrils & down your throat.
One other point is that the TCC lockup failing has a noticeable effect on fuel economy. When mine stopped working I only realised it due to the extra fuel it was drinking (I didn't even realise that the converter locked up before I read the manual. I hadn't had it long and it was all new to me, big V8, no idea where the front was, no clutch pedal, changed gear on its own, people kept staring, TCC lockup, what's that?). The extra fuel it drank each week was enough to pay for a few pints of beer. And that's a serious problem
Good luck with it, TCC lockup can be a real pita at times.

Kalway

Holy crap Paul wrote a book! Not worried about gas mileage as much any more because I've got the motorcycle coming and the vette is going to be a toy, mostly. Plus I'm going to put the 2004R in next year. There wasn't a lock-up on TH-350s for like 8 years and they worked fine so I'd imagine the TH-350C will work just fine w/o a lock-up. Least that's what the vette shop told me.

Anyways, will removing the EGR valve increase performance at all?

bobs77vet

i guess he doesn't use the hunt and peck method like the rest of us...it would take me week to type that much.

UKPaul

Yeah, sorry about that, I must have been on a roll I figured that as I could have really done with the info when my TCC lockup failed, I'd post all the info I could (& bury it in lots of verbage!).
Not sure if the EGR valve removal will give any increase in performance as mine had long gone when I got the car.
The Th350C will work fine without the converter locked (mine ran OK with it not locking, it was just my wallet that was hurt).
This post will be short

Ybnormal

UKpaul told me how to hook mine up and it worked fine with only +12 a switch and a ground. Now when I'm on the highway and want lock up I just hit the switch and it will lower the rpms. Not a real big difference but every little bit helps with the price of gas now day

Thanks UKpaul
YBnormal...drive a vette

www.angelfire.com/al/swhite7/vette.html

kevinator80

UKPaul, Would this info/procedure apply to an 82 with 700r4 after swapping to a carbed engine?

UKPaul

Hi,
No, the above book ( ) applies to the th350c. My 200-r4 was different & just needed just a switched live connected to it (earth is via the trans case), as opposed to the th350, which needed a permanent live & a switched earth. I'm trying to find the information on the 700 but there's different wiring setups in different versions. Does the 700 fitted in the '82 only have TCC lockup in OD, or does it also lock in 2(?) & 3? How the internal wiring is set up shouldn't matter, as the external wiring will just need some slight modifications so that a switch can be fitted to do the job of the computer.
If you visit Bowtie overdrives website you'll see that they've got TCC lockup kits for the 700, but you'll also see that the internal wiring on the 700's varies according to what model/version it is. These kits cost money & it seems a waste to fit one rather than modify the external wiring to get it to work (which will just cost a few cents for connectors & a switch). What their kits appear to give is a new TCC solenoid & pressure switch that are fitted inside the trans (to replace your working ones) & are then wired up in a simple configuration. Your trans may be wired internally just as their kits do it, or it may not (if you're due a fluid & filter change draw a pic of how the trans is wired up inside). Have you got a wiring diagram for the stock system? Better yet, are there any on the Net that I could get a look at? All we need to find out is how the computer demands lockup. Once we know that then modifying the wiring should be fairly easy.
The way to do this is to use the existing TCC brake switch & fit a manual switch for selecting lockup manually when in OD (or 2 switches can be fitted if lockup is wanted in the lower gears as well - but who ever uses a Vette for towing?! NB. the towing option just means that the TCC is wired to lock in 2(?) & 3 as well as OD).
What I've done on my 200-4r is to wire 12v from the TCC brake switch directly to the trans. I haven't fitted a switch to turn lockup on/off. When the trans changes into OD then, about a second later, it locks & stays locked until I either brake or manually change down a gear. I'm happy with the way it works & probably won't bother fitting a switch at all, but I can see why somebody would want to run in OD with the converter unlocked (with my 2.87 rears I knock the trans into 3 for "spirited" driving). Something with these OD trans units is that they stay in OD when slowing down, right down to about 40mph (1000rpm), requiring a manual shift out of OD when slowing down. Does the 82 700-r4 behave the same, or does it shift down automatically when slowing down?

kevinator80

Apologies to Kalway for highjacking. Thanks UKPaul. I have no wiring info for a 700r4 but will see what I can find. I may give you shout before I swap to the carbed engine in July. I am sure BTO can get me going but I would like to do this on my own if possible.