One piece of info that's missing is the manifold pressure switch. It's there so when you go to WOT the manifold pressure drops and releases lock up selonoid...

 

81$$pit: what comp cams did you go with?

 

I gotta say I am starting to get alarmed in these forums by the number of guys ripping out the ecm, carb and distribs from these 81's. I am about 6 months into rebuilding the 81 I bought from someone who has had it sitting outside on blocks for the last 10 years. I intend to keep as much of her original as reasonable and don't see anything all that complicated about the ecm system from the shop manuals. My biggest concern is that I might not be able to get parts as more and more of these systems are abandoned.

if anyone wants to sell their 81 ecm, original carb or various solenoid, wiring harness or connectors, please drop me a private email with description and price. Maybe if I get a backup of everything I can keep her all original for another 30 years.

Wade
wadebee@hotmail.com

 

There is nothing 'wrong' with the '81 system if the components are all functioning and the system is working as designed. Could it be improved? Sure. That's what the later ECM systems did. But, the '81 system did what was expected of it: better emissions control, better fuel mileage, smoother idle, smoother start ups, etc., etc.

If you can't work with 'wires', pull your computer off and go back to "old school" controls (pre-computer). Otherwise, leave it alone if it works.

 

 

CL12-214 I believe was the model #
Magnum 305H

 

I know it seems my new lot in life is to ask you to prove your assertions when it comes to the 81 computer, so here it goes again.....Where did you ever get the impression that the 81 computer was derived from anything but the new emissions requirements that Chevy was trying to get to in 81? It had nothing at all to do with the small increase in MPG the lock up converter did that and it could have done that with out the CCC. As far as idle goes, that is not at all true, a non computer 80 idled as smooth as silk when new, park them side by side and you would not have noticed any difference. Startability, again, not enhanced by the computer. And as far as etc, etc....what are those? I have no problems with you continually praising the computer, but I do when you make it sound like it was added to the car to "improve" anything that is simply not the case. It was years after the 81 before a computer enhanced the driveability of a car. I don't think the 81 did anything to take away from any of the things you mentioned but it darn sure did nothing to improve upon them. And thats a fact. All it did was add another layer of troubleshooting when a portion of it goes bad, and yes I said when and not if....

And wiring I enjoy, so not the reason I yanked mine. It seemed to be working improperly, and not worth the effort to fix for ME. I have never regretted it. And no that does not disqualify me from having this opinion...

 

WOW, that is a big cam That cam has more duration than my 10 second LSx drag car!

 

Another 81 CCC bites the dust!! I will have the last one soon -- the last Dodo

So why do I keep it (and love it by the way). Because that is the way it was meant to be. I am an electrical engineer and have done some pretty sophisticated stuff in my career (I AM a rocket scientist!) and I can assure you the system is elegant in its simplicity. It was the first ever, and it worked quite well and was extremely reliable. The electronic carb should be shown in engineering schools as the model for simple, elegant solutions to a complex problem.

I keep it because it deserves to be kept. I am proud of the fact that I understand it, can diagnose it, and make it work. I am proud that I can open the hood and show people the ugliest engine compartment of any sports car ever made and describe that NO other corvette was ever like this (for a reason!)

Lets face it, the 81 is no race car and would not have been with or without a computer, 81 was not a good year for american cars -- Slowest fast car ever made. But it is special, unique and so ugly its beautiful and its mine and I love it!

 

I fudged..I checked the box, its a CL12-212..
Its a Magnum but a little smaller.
It still says I need a stall, gears and headers...

I have 355's I think, no stall, factory headers with smog crap removed and welded shut with Pacesetter exhaust so it seems to breath pretty good.

Problem now..I got a Holly 670 Avenger they ordered by mistake, I put it on a few weeks back but then had elec problems but got it started yesterday, drove to the gas station to fill up before storing all winter and it stalled out on me before I could turn into the gas station and it ran like crap on the way home too.

I tried to tune it, bumped idle up to 1200 rpm at idle and it stalls as soon as I put it in gear

 

I've not heard good things about the avenger series..just sayin..

 

You ask someone for proof of somthing they claim, then you spew ---- and say "that's a fact"?

Yes, the computer was born of the need to meet federal emission standards. The old Quadrajet did and admirable job, but it had reached its limit. The computer allowed the system to run more efficiently, burning less fuel to do the same work from start up on. If this was not true, the system would have never made it into production.

Once you know the system, which many of us have taken the time to learn (it's not rocket science), it is very reliable and the computer actually assists you in trouble shooting.

As far as performance modofication, I can shred a set of tires at will, have had the car up to 150 mph (and the car still had more, I just did not) and I still get 23 MPG. That would not be as easy (if possible at all) without the computer, and I still have not even come close to the system's performance limit!


Yes, you are welcome to your opinion, but it is NOT fact!

God bless, Sensei

 

23MPG ??? If mine got close to that I would not have changed a thing.
I could not get mine running right with it and still cant get it running right with out it. I got 10 MPG before and 11 now.

 

I took mine on a trip to Galveston the other day and got 22 mpg, no joke. It is possible. That was mostly highway driving, but some city driving too. But I spent alot of time getting all my vacuum leaks sorted out and made sure the engine was pulling plenty of vacuum (21", before it was only 13") prior to that.

 

EXACTLY! Your car was not running correctly and instead of diagnosing the problem, you threw out the computer etc, and you still have the problem!

The issues with the stock L81 are:
-Restrictive exhaust
-Crap heads
-Dismally low compression
-Anemic cam shaft
-Retarded timing

If you want performance and efficiency, that is where to spend your money.

If the thing is just not running right (which yours is not if it gets 11 mpg), get a factory service manual and follow the littanies to diagnose the problem and fix it.

God bless, Sensei

 

Sensi, I'm sure you have posted it before, but what heads and cam did you select to beef up your 81? I'm bone stock and looking to upgrade both.
Thank you,

 

Just looked at your profile and there was the answer to my questions!
Thanks,

 

I spent several hundred dollars taking it to a few different shops and nobody could figure out why it ..
1) got crappy gas mileage
2) starts slowly when hot.

after 3K later it still has those issues. One problem was someone took out the check engine light. I pulled the seatbelt light and put it in there so it stayed on al the time took it in and the codes would not flash.
After that I drove it to work one day and it started sputtering and would not get up to speed. Took it to a new shop and they said it was the carb and it would be 500.00 for new but couldn't guarantee. That was the problem or the sloppy timing chain, so instead of keeping all that crap on there and trying to diagnose it why not remove it and get a 300.00 carb and 150.00 dist, Then of coarse to change the timing chain it was an engine pull. So "while its out" ....oil pump, fuel pump, cam and lifters, clean up and paint...on and on.

 

I don't think you have to pull the engine to replace the timing chain

 

It sounds to me like some mechanic shop found themselves a goldmine. They do that sometimes..