Golden80

currently have an LG4 with the ECM that controls the carb, tranny, and distibutor. I'd like to put in a ZZ4 and need to stay emissions legal for Air Care Colorado. How do I go about this? Do I just need to use the old distributor and rejet the CC QJet? I'm planning on keeping the TH350 with the lock-up TQ converter for awhile too.


[Modified by Golden80, 7:17 PM 2/13/2002]

KenSny

Isn't an LG4 a 305? If so then I would think the ECM prom, and the carb would need to be upgraded.

Golden80

Yep. 305. I forgot about the PROM. Any ideas on where/how to get one for a ZZ4?

Matt

BSeery

Yes.

Depending upon the CFM rate of that carb, you should be able to use it, once it is tuned for that motor.
I dont know if the same distributor can be used as well by just replacing the one that comes with the motor. Since the ZZ4 comes with a roller camshaft, more investigation as to what drive gear is on the new distributor may be in order. You could take the drive gear from the new distributor and put it on the computer controlled one and then use it. Better yet, transfer the equipment from the old distributor to the new one.

By the way -- my ZZ4 passed emissions just fine -- My results are posted here.


[Modified by BSeery, 5:21 PM 2/11/2002]

Golden80

Looks like it will be a lot harder than I thought. The comp system in mine is too unique. All of the chips to convert it to a ZZ4 intake that I looked at are for later modeled LG4's in the Camaro's with the 700R4. Looks like I'll need to buy an entire comp control setup from a later model, a 700R4, and a chip to make it work. Guess I'll just hold out until 2005 when I can rip all this crap out and stick it in a corner to do an engine swap. :sad: :sad:

My next question I guess. If I were to swap it to a full TPI setup would it be emissions legal? Is this something I'll have to call my local Smog ***** on?

Matt


[Modified by Golden80, 8:58 PM 2/11/2002]

Smokehouse69

Matt,
How sharp are the Colorado smog *****? If you put in a ZZ-4 or a crate, with all the external smog equipment on the thing, are they smart enough to tell the difference. If you still have your pump, your egr (or reasonable facsimile), your cat and and the car is tuned correctly, shouldn't that be enough to fool them. As long as your CO and hydrocarbons are in line, you should pass. If you engine is new, your carb and timing set right, your exhaust ought to be clean.
I know that the many of the guys doing emissions testing in Texas are nearly morons when it comes to a car more that 10 years old. You should have seen them trying to figure out how to pressure test the gas cap on my 69 (vented cap, about 4 inches wide)

Golden80

I'm not too sure on how sharp they are. My friend that I bought the car from said that when they took it to get e-tested that the guy plugged it in as an L48 at first. But my friend corrected him. Maybe I could get away with a regular QJet and distributor. I think someone said that you can run some sort of vacuum line for the lock-up TQ converter too. How would I do that?

Matt

VegasJen

here's a thought and i don't know if it will work but maybe it's worth a try. get the zz4 and a chip for an '81 4-speed car and use a dash mounted switch to lock up your torque converter. the carb should be plenty big enough for a zz4 and probably the worst thing you'll need for the distributor would be a bronze distributor gear.
i don't know if it will work but, hey, it's a thought! :)

Dalannex

The computer controls the lockup of the converter, the timing advance, and the air fuel mixture of the carb. Everything you have should work fine, except for possibly the drive gear on the distributor, like was mentioned previously. As far as the carb goes, you will probably need to swap metering rods, but the only thing the computer does there is adjust air fuel mixture by pulsing the mixture control selenoid to open or close the primaries more. It uses information from the O2 sensor, TPS, and a temperature sensor. All of this will remain the same. You will need to rejet primarily to obtain the maximum HP out of your ZZ4.

-Justin

Smokehouse69

Matt,
I thought that the 81 was the only year to use a TH350L (lock up Convertor) I don't know, maybe the California 80 model had it too.
I personally think you could get away with a standard Q-jet (or even an Holley) and a HEI distributor with vacuum advance, as long as your car passes the pipe. It should pass the pipe as long as the carb and ignition are well tuned and it is warmed up fully.
If your car has a lock up convertor it is easy to rig a toggle switch, or even a vacuum actuated switch to control lockup and another switched tied to brake pedal to kill lockup. Everybody that has a 700-r4 or 200-4r has to do this setup. I think Jegs and Summit carry the stuff you need to convert it.

BSeery

The 1980's had the 350C transmission, with a lock up convertor.
The lockup worked off of a firewall mounted vacuum switch, that was also tied into the brake pedal as well.

I have since switched mine to the 700R4 and am trying to get the lockup to work with the existing setup.

I will post my results when done.

DaveL82

Why not use the L48 or L82 system in your 80. These were legal in all states except for California, which had the LG4 305. Check with the state, but you should be able to use the non computer L48 ignition (change cam gear to match roller as mentioned) and obtain a non computer L48 Rochester carb. I run the rochester on my 1980 ZZ4 with no problems. In fact Edelbrock sells an emission leagl rochester replacement complete with the fule vent ports.

This should be legal, but you must check with the state first. As an FYI, the ZZ4 is not a leagl smog motor, but how careful will they check?

Gator81

Dalannex's reply, above, is pretty complete. I believe the only issue remaining is the compatibility of the ZZ4 cam with the ECM. Your LG4 system, just like the '81 L81 system, uses a vacuum sensor (more properly called a manifold absolute pressure, or MAP, sensor) and it's pretty picky about the minimum amount of vacuum it will allow.

Getting back to your core question, it is certainly possible to just swap a hi-performance long block underneath the original carb and emissions gear (I did it) so as to remain completely or nearly smog legal and to easily pass the tailpipe sniffer test. In my case, I did it with a 330hp crate motor from Summit Racing. It uses the Crane CompuCam 2040, which is the hottest cam I know of that makes enough vacuum at idle to satisfy the MAP sensor and thereby satisfy the ECM. You just pull the LG4 out, transfer all the stuff over to your crate motor (air pump, EGR, exhaust manifolds with AIR fittings, HEI distributor, plus all the thermal vacuum switches and hoses) and drop the new motor back in. Put a Hypertech, Jet, or custom chip into the ECM to give you a timing curve to match your cam and compression, and go.

Take a look:
http://www.rogerscorvette.com/free/morris.htm

If you wanted extra insurance against the rare overly-curious smog inspector, go ahead and paint the new motor that lovely Chevy Blue of the old stocker, and make sure you re-install the old valve covers. You could have a 383 stroker under there, and it would still pass the test just fine and although it would be technically illegal, noboby would ever know or care.

The only catch is, the cam. The cam's gotta make enough vacuum for the ECM to work right at idle, or it'll never run clean enough to pass the test. As I recall, you need a vacuum reading of something like 14 (inches Hg, is it??) minimum for the MAP sensor to be happy. The Crane 2040 will pull 16 easily. What will a ZZ4 cam do? That's your 64-dollar question! If you can count on 15 inches of vacuum out of a ZZ4 cam, then the swap will work. It's been 6 or 7 years since I did all that research, so I may be goofing up the vacuum numbers, but you get the idea.

Mine runs cleaner on the tailpipe sniffer now than the stock L81 ever did. I regret getting "only" a 355 c.i. crate motor; I would never go back into it again for anything less than a 406. And it would still run clean.

Golden80

Gator81-

I'm not sure if the ECM in mine picks up the vacuum from the cam. I could definately be mistaken though. My computer system is the predecessor to the ones they put into the 81's. From what I've read/heard it only controls the carb, distributor, and possibly the tranny lock-up. Does the cam affect one of these parts? Is it affecting the O2 sensor possibly?

Matt

Dalannex

You do have the sensor that reads vacuum. I think the biggest problem you will have with low vacuum will be that the carb will dump fuel in when the car is idling because it will think the car needs more fuel. Actually the fuel will be puddling up on idle. Then when you step on it that built up puddle of fuel will get sucked back into the motor and cause a serious rich condition. I know this for a fact because I had too large of a cam in and experienced just this problem. If your cam has that 15 hg of vacuum you will be just fine with what you have. BTW, that sensor is located at the front of the intake manifold to the passenger side of the thermostat. (I think, it's been awhile since I did any work on mine)

Golden80

I was checking out the Thirdgen.org since there's a lot more LG4 Camaro's than Corvettes. It looks like the best thing to do would be to get the ZZ4, use the stock chip, rejet the carb, and install a Comp XE256 cam for the vacuum. I'll keep the ZZ4 cam until it's emissions exempt and slap it in when I'm done with my last E-test. Or perhaps I'll buy a better cam to put in when the time comes. Who knows?

I guess my next question is how will the XE256 affect the rest of the ZZ4? I know it will give me a performance loss but will it still work?

Matt

Dalannex

What are the specs on the XE256 and on the ZZ4 cam? Or, what are the specs on the XE256 and how much vacuum does a ZZ4 run stock? I am thinking it is lift of around .40 with a 256 duration???? I would think you could go bigger than that.

Oh yeah, isn't the ZZ4 a roller cam? That would probably give you more options on cams that I'm not aware of. I've never dealt with anything but hydraulic flat tappet.


[Modified by Dalannex, 6:11 AM 2/14/2002]

Smokehouse69

Matt,
The ZZ-4 uses a roller cam, so you'll have to go with a roller when you go with the new cam. I really think that you are worrying too much about the emissions testing. As someone stated above, the L-82 and L-48 specs were legal for everyplace in the USA except California, set your car up to look like one of those engines. Just put your external emissions equipment, a non-computer controlled Q-jet and a vacuum advance HEI on your car. If it is tuned to correctly, it will pass the CO and hydrocarbons pipe test. My car came from Colorado, it had a current emissions certificate from Colorado when I got it. The car was no where near correct tune and ran like a dump truck, it passed the pipe test without a problem.

Ganey

The el. Q-J may only need the sec. jetting changed. Easy to do, 1 screw on the top.

Gator81

Golden80,

I'm not aware of any differences between the Computer Command Control (CCC) system on the '80 LG4 and the CCC on the '81. I might be wrong, but I believe they are the same.

While I'm no cam expert, the relationship between cam and vacuum is pretty basic. A high-performance cam makes more power at higher revs by keeping the valves open longer (more duration), giving the stuff more time to get into and out of the cylinder. That also produces more overlap, that is, more time when both valves are open a little bit as the exhaust isn't quite closed yet but the intake is already starting to open. At high rpm, the exhaust charge has enough momentum that it doesn't get sucked back into the cylinder as the piston starts down on intake, even tho the exhaust valve isn't quite closed yet. But at idle, the exhaust charge has much less momentum, and it does get sucked back in. The piston, on it's intake stroke, is actually able to pull through both valves. This results in less pull through the intake valve, and it's that pull that produces vacuum.

Modern cams are able to accomplish the objective of having the valve open longer at higher revs, but without so much overlap, by having steeper ramps; that is, they open and close the valves faster. So the ZZ4 might still work just fine. Call one of the places that sells it, like Scoggin-Dickey, and ask "how much vacuum?". Roller cams, like the ZZ4, are even better at doing this than flat tappet cams like my Crane 2040.

About the emissions test: Your '80 LG4 will have to pass the standards it was originally certified for, I believe. And the tester knows that (if he's using the modern IM240 equipment) because the VIN code that he types into the computer tells him so.


[Modified by Gator81, 9:56 AM 2/14/2002]