Hi All,

I have an 86 Berlinetta that was originally powered by an LG4. The PO hacked the cc carb wiring harness to death and I ended up removing and junking.

I eventually swapped in a crate 350 (sp350/357) and an AVS2 Edelbrock. I know this sounds ridiculous, but I'd like to get another cc carb/harness and try to modify to work with my crate motor.

The Edelbrock is decent, but I've heard good things about the reliability/fuel economy benefits of a QJet. I know it will take some work, but I think the CC carb has a cool factor to it...

That being said, I'm looking for suggestions on what I would need to accomplish this. The sp350/357 utilizes a camshaft with a slightly more aggressive duration than the zz4 (215/223 w/108 lsa). It makes good vacuum at idle so it appears that with some work I could utilize the cc carb.

What I've read I'll need:

• lg4 engine harness
• CC Carb
• change hangers to match fuel demand
• 87-88 el camino HO ECM
• Burn a copy of the zz4 prom (or find one on ebay)
• narrow band o2
• cc distributor
• knock sensor for 350?
• 16128261 spark module?

Let me know your thoughts.

Thanks,

 

No zz4 calibration available. Fitech efi or non ccc would be my vote.

 

I was thinking about following the steps written here: http://www.montecarloss.com/communit...&Number=888945.

I think I saw an older post on here that had the files necessary to make the zz4 prom.

 

I have the carb, distributor, wiring harness mostly complete with sensors and pcv system, also upper & lower radiator hoses, I removed all items in working condition when I swapped to LS this spring on my 82, carb worked really well with no bogs, I installed larger secondary rods & on my mildly cammed 350 air/fuel was right at 12.5. Parts were removed with 58,000 miles on them so lots of life left, I have pictures of carb in classified section, shipping will cost more than parts, pm me if interested.

 

Go to fuel injection. There is very little support for the CCC. Computers are all old as dirt and likely to have component failures and/or circuit board cracks. It's not worth the trouble.

GD

 

I think it really comes down to being able to do a tune that accommodates the lower vacuum of the larger camshaft. The PROM from the GM Performance ZZ4 conversion would probably work fine, but you can't get those anymore. I guess if someone was able to to burn a new PROM for that ECM, that would work, but not sure how possible that is for those ECM's. If getting a proper tune becomes too much of a hassle, then I would just go with a non-computer carb and distributor and call it a day. Set it up right and it will run fine.

 

the stock LG4 prom will likely run fine, although some improvement may be noted with the HO or hotter proms.

the tune differences are primarily in the spark advance. the mixture control is just a dwell change in response to O2 readings. do not assume the ccc-system can be 'tuned' like FI for a more aggressive cam.

I've got a stock 84 LG4 with antique tags that never gets driven and a 85 LG4 with an L31 controlled by the ccc-qjet that hardly gets driven. as old as the ccc-qjet and related parts are, it's getting more difficult to keep the systems maintained.

if I had to source the pieces/parts to put one together, I'd probably go FiTech, like the system on my 87..

 

It's not so much the spark advance of the LG4 vs. the L69, but rather the spark maps are dependent on the manifold vacuum reading from the MAP sensor. With a bigger cam, the idle manifold vacuum will be lower, so the computer will think the engine is under more load that it really is and retard timing. It would be OK at WOT, but everywhere else it would be off. I'm sure it will run and bumping the base timing might help a little, but it won't be right.

An L31 using a stock LG4 chip probably does run well. The L31 cam is pretty small. The intake and exhaust duration is in between the LG4 and L69 cams.

Agreed that the fuel mixture "tuning" would not be within the PROM. The primary side of the carb would be adjusted at the carb for proper dwell and that will let the ECM adjust air/fuel mixture correctly during part load using the 02 sensor as feedback. At WOT or close to it, the secondaries use mechanical metering rods (no computer adjustment) like any other QJet. Changing metering rods on the secondaries will change the air/fuel ratio during WOT.

The CCC carb system is actually works pretty good when it's all dialed in correctly and it's relatively simple.

 

Thanks for all the replies.

Obviously the system has limitations. I already have a sniper EFI setup, but I'm not sold on the reliability/longevity.

I've broken down several times and about 2 years ago one of the injectors stuck open and locked up my 383... The motor was unfortunately ruined. Cold weather starts were great, but I was constantly worried about something electrically going wrong and being stuck on the side of the road. I ended up swapping in the AVS2 and a mechanical pump. The Sniper is now sitting in a box along with an inline high-flow Holley pump.

I'd like to go to a factory setup due to reliability. I've heard the CCC QJET can achieve great fuel economy. I think the key will be getting it to idle with enough vacuum so the computer can read properly.

 

for reliably getting your car to move, the ccc-qjet system is fairly robust. you can yank out the entire ECM and still start and drive the car.

I've run the ccc-system with the XE 262 cam in a 350 using the LG4 prom. idle was a bit rough but I routinely averaged a hair over 20 mpg, above 25 on the highway (3.27 rear). that motor got a hot cam and a T56 later. idle was still a bit rough, at 800 rpm (but no more converter drag). a swap to the zz prom under that combo made no noticeable difference. I suspect most of my idle issues were related to the inadequate idle feed circuit. I had some venturi drip under the hot cam at idle. debated drilling out the circuits or swapping to fitech. the fitech now on it idles smoother.

if you can score all of the pieces/parts..and pay attention to detail when you rebuild and set up the carb, you might be fine. I've never been beside the road because of a ccc-system malfunction. distributor, fuel pump, fuel boiling, yes.

if you need help with anything, or need a fiddly bit or two, ping me. I can't get rid of a whole system as I may have to provide future support for two other LG4s, but I may be able to spare a piece or two.

 

It is a pretty decent and simple system and certainly does help with drivability in all conditions and fuel economy when compared to a standard non-computer carb system. I had an 86' with an LG4 and a 5-speed. It was all stock and it would get about 23 MPG on the highway and it started up and drove just fine whether it was 5 degrees or 95 degrees outside.

 

Honestly the Holley entry level stuff is hot garbo IMO.

But that's definitely not the case with all FI systems. FiTech in particular seems to have a lot of happy customers in my experience.

There are other options too like going to a FIRST manifold and some of the more complete FI systems and standalone wiring harness, etc.

You are talking about going to a factory system for reliability, but then modifying it..... the stuff is old, the parts difficult to source..... what do you do for support? I don't think it's ideal and honestly I'm super amused that *anyone* would actually be pursuing installation of a computer carb system from the 80's with the goal of daily driving it. We remove these type of systems routinely on old carb applications because they are usually a nightmare.

GD

 

I ran the stock CCC QJet on an LG4 with a K1104 Summit cam and it ran ok just didn't idle well at startup and seemed like it was searching in stop and go traffic. Did away with it and went with Holley and never looked back. Today I would look into FI-Tech, that's what I should have probably done with my present car istead of upgrading my TBI but we will see how that works real soon.

 

I am not an aftermarket EFI system fan at all. The best PCM for a small block available for a daily driver type of build would be a port fuel injection intake with factory GM injectors and sensors, run by a LS PCM with an EFI connection 24x reluctor and coil near plug ignition. 2nd option would be using a vortec reluctor and distributor setup. Parts are cheap and available anywhere at a local parts store.

I am slightly over 500 hp with a ported GM Vortec truck intake and GM electronics minus DUI upgrade coil and module. If necessary stock 350 vortec parts can get me home.

 

Update on my CCC Qjet endeavor:

I was able to score the parts I needed thanks to a couple ThirdGen members (including a ccc qjet with larger hangers). I also floated around the montecarloss forums and ended buying an 1228079 pcm.

They have some great write-ups/files for tweaking the pcm and I was able to burn my own custom "zz4" tune. I also changed some timing tables for the vortec heads and removed the diagnostic mode. This should allow me to connect a code scanner and read the dwell/timing/tps values while driving... theoretically.

I'm pulling my engine this weekend to replace my TQ converter, clean up the engine bay and install my wiring harness. If all goes well I should be able to test out the setup soon!

 

Its funny to me you are working on putting a CCC Q-Jet in a car. I had a .ECU file for an Oldsmobile 830 back in the day and ran a 403 under the 307 Vin 9 carb in an 88 Cadillac.

That being said I have built many of the 79-84 850cfm truck Q-Jets. Strip them down completely, new throttle shaft bearings, sonic clean everything, mild acid (vinegar and water floowed by muratic acid), then zinc replate, full recalibrations. One of the last ones I built for a 500 cadillac swapped in place of a formerly 455 oldsmobile powered front wheel drive GMC motorhome was built with the outer primary booster rings removed as well as the primary metering rods and power piston blocked off. The combination gave alot more torque on the primaries via slightly richer mixture and more primary airflow which is exactly what a heavy motorhome needs for torque without having to open the secondaries. Fuel mileage was better with the tweaked carb and 500 Cadillac than it was with the stock olds and stock rv carb. With the gutted primaries it still idled at 14.2:1 air/fuel ratio, ran in the low to mid 13s with an open throttle and dropped into the mid 12s at heavy throttle and WOT. Couldn't ask for a better fuel curve for the application. That RV had no problems cruising 80 mph on the primaries on flat road. The stock 455 was into the secondaries at 65+ mph.

 

Fast,

My car originally had an LG4, but the previous owner ruined the computer harness/carb. I tore everything out and stabbed a dummy fed 383, but now I've come full circle in search of reliability/mpg...

Sounds like you're quite the expert on these carbs! My biggest concern is the idle vacuum in gear. I've been told that increasing the initial timing could help, but I'm afraid I may have to make some physical mods to the carb. Any suggestions?

Also, the carb hasn't been used in some time, but was working fine before storage. Is there anything I can do to prep it before use?

 

I'm VERY interested. Keep posting your progress.

 

You are going to have to physically modify the carb to get where you want to be. The CCC system mearly trims out the fuel mixture in closed loop. The WOT and open loop mixture is still setup in the build. You have to get the carb circuits somewhat correct so that it functions properly in open loop and then dial in the rich and lean stops. The CCC Q-Jet actually gets worse mileage than the non feedback carbs. The CCC Q-Jets are better only from an emissions standpoint because they oscillate the mixture richer and leaner than 14.7:1 to allow a 3 way catalytic converter to function properly. A well dialed in non feedback mechanical Q-Jet can cruise in the 16-16.5:1 air/fuel ratio range at light throttle.

 

It's been quite a few months but I did get the original setup to work on the engine stand! I was actually impressed with the idle quality and I think it went into closed loop because I could hear the mixture control solenoid working. Testing was done with a computer from an 82 but I'll be using an 8079 (LG4 HO) computer with a custom tune once it's in the car. If I can figure out how to upload a video I will.

 

There are quite a few people who still specialize in the older Non-Electronic Rochester Quadra-Jet.
It would be worth while to have the Carburetor gone through and tuned by one of these people.

You can then finalize the Carburetor with a PROM/ Tune.

 

Update for anyone interested:

The car is finally driving again. I'm fighting a slight lean condition but overall it's running quite well. Idle quality is really nice and the Quadrajet secondary's seem to make a big difference over the Edelbrock AVS2. FYI the TPS voltage seems to really affect the off-idle acceleration. I'll post a final update once I get it dialed in more and calculate the gas mileage.

 

Fantastic, the CCC Qjet is a great carb, keep us updated

 

Where does it run lean? Have you checked the MCS duty cycle?

 

Fast,

I'm having issues getting the dwell set. It reads just 20 after warming up. I've adjusted the IAB all the way in and it will still read 20 - I've also pulled the mixture screws out 7 turns from seated and it has no affect. Idle quality is great (park or drive), but sometimes under initial acceleration and full throttle It's stumbling/hesitating. At full throttle it feels like a lean misfire.

 

It’s a bit tough admitting this, but part of the issue was self-inflicted. The air horn torx screws were loose and causing a bit of fuel seepage. If anyone knows the torque setting for these it would be greatly appreciated. Also, one of the vacuum ports under the tps was uncapped... between the two I’m sure that’s enough to cause a lean condition.

After the engine warmed up the dwell was reading 10-20. I ended up turning the mixture screws in one full turn and the dwell is now 25-40 (five or take a few)! I increased the TPS voltage to around .70 and the car is driving great! No lean spots and off-idle acceleration is very smooth. I’ll report back when I get some mpg info.

 

What rods? What hanger? Often a lean miss feeling at WOT is from an air door setting that is too loose or a secondary cam (one that moves the secondary rods) that is worn. The wrong taper on the secondary rods, too small of a power tip or a hanger that is too far up the alphabet will all contribute to lean WOT especially as the secondaries open. Finally most Q-Jets need modification to the secondary air doors as well as the secondary POE to get good response.

 

I just wanted to give a quick update - I was able to get everything running well enough to take the car on a vacation from Florida to Texas and back. I think the secondaries could use some tuning but I was pleasantly surprised by how well the system works together. I averaged about 20 mpg on the trip but I'm hoping with some fine tuning I can bump that up.

 

That's awesome, the computer controlled carb does not get nearly as much love as it should. Too many Edelbrock downgrades out there I love seeing someone upgrade back to what it should be.