Checkerbelly

Hi everybody.

I bought an 85 camaro z28 with a 305 engine recently. It seems to run OK right now except for when I put my foot down on the gas pedal any more than typical daily driving. If I stomp the gas it bogs down.

Bear with me, I know next to nothing about this stuff and I'm really new. I'll try my best to explain my question:

The carburetor original to the car was electronically controlled. The carb currently on the car is NOT (it's also a quadrajet). So I have plugs just dangling around in my engine compartment not doing anything but collecting dirt.

I've read stuff on the internet about the difference between electronically controlled vs non-electronic and it seems to me that the situation my car is in now will make my car run rich, get lousy performance/mileage, kill the spotted owl, etc, etc.

Is that true? If my car's computer can't see what's going on in my carb, is it destined to run like crap? Or can it be tuned?

Part 2 of my question:
A buddy of mine GAVE me an electronic controlled quadrajet to try out. It seems to have all the correct receptacles for my loose plugs. I'm worried that some of my dangly plugs might be so crapped up with crud that they won't work properly when I plug them in. Or that there was some issue with a sensor or the computer or wiring that made the original owner want to abandon the computer anyway... If I install this carb and plug everything in and it still runs like poo, what are my options?

Basically - can I ever get my car tuned properly?

Thanks for any advice.

naf

iTrader: (7)

Some of this can be checked without swapping the carb in.

First: Does your motor still have the electronically controlled distributor? It should NOT have a vacuum advance can on it.

Is the ccc-qjet you have in good shape? You can plug in the Mixture Control Solenoid (two-wire connector on top) and with the ignition in 'run' it should begin clicking. If the engine isn't started in about a minute the ECM will command the MCS to stop.

The three wire Throttle Position Sensor pigtail should be providing five volts on one lead and a ground on the other. The third lead is the signal back to the ECM. I'd have to look up which is which but if you find five on only one and continuity to ground on only one you should be good as it's unlikely they'll jump legs.

Aside from that it shouldn't take more than 20 minutes to swap carbs. (Always make sure you use two wrenches on the fuel line to keep it from twisting). Clear your ecm trouble codes prior to swapping by disconnecting the ECM connector which should come off the positive cable near the battery. Start it up with the ccc-qjet and report back how it goes.

There's some sticky info at the top of the carb forums on servicing the qjet you may want to peruse. There may be some adjustment required swapping your ccc-qjet on and you may want a dwell meter (or scanner) to verify that everything is working properly.

Most ccc issues are with the carbs and can be resolved with a rebuild. I've found the TPS sensors in the carbs to be the most troublesome part. Outside of the carb are the O2 sensor, Coolant Temp Sensor, Vac sensor and baro sensor. The O2 should be changed regularly, the others rarely fail although the pigtail to the CTS can be an issue. I've replaced quite a few. I would encourage you to try to swap back.

BahN

just an added note, it sounds like the secondaries are coming in to soon on the non-cc qj. Try adjusting the secondaries to open later

Checkerbelly

Cool, thanks guys. I'm going to tinker around with it and maybe slap the new carb on it this weekend. I'll need to look and see whether I have a vacuum distributor or not. I'll also need to look for my oxygen sensor. The previous owner did away with the cats so I'm not sure how my computer feedback is going to work out. Maybe thats why he put the non CCC carb on in the first place... ugh.

Checkerbelly

I peeked under the hood tonight and it definitely looks like a vacuum disk thingy on the side of my distributor. I checked and it's connected to the metal piece that the distributor cap mounts on. Also, I have since replaced this cap and rotor and when I had the rotor off, I remember seeing a piece in the center with two springs.

Anywho, there's a 3 or 4 socket plug dangling just off to the right of this distributor. Could that be an input that was used with a computer-controlled distributor?

I'm starting to think that the original owner did more work than he let on. And I shouldn't try this free CCC carb I got. Any thoughts?

Here's my engine bay before I touched anything. See the gray vacuum disk thing on the passenger side of the distributor?

naf

iTrader: (7)

Yes the dist has been swapped out for a vacuum advance unit. The four prong connector next to it is the ECM connection to the computer controlled dist.

Simplest First: you've got alot of varnish and gunk on your carb and linkage. Get some spray carb cleaner and clean it up as well as you can. This gunk can gum up the linkage and cause sticking chokes and air valves which could cause your problems.

Next I'd check your timing and ensure it's set properly for a mechanical dist. Try 18 BTDC with the vacuum line to the advance can DISCONNECTED (and PLUGGED at the carb port). Verify that the mechanical advance is working by revving it with the timing light on it and seeing that it advances to around 35. You may have to estimate the amount of advance for now because the timing marks won't go that high, but the important part is that it does advance.

Take it to a spray car wash with a brush and some engine degreaser in a spray can, maybe two. Spray that baby top and bottom and scrub that gunk off. You can place a plastic bag over your carb which should be shiney from it's previous cleaning. Use the magic car wash spray wand to transfer all of that oil and grease into the car wash's grease trap.

Are there headers on there? The O2 bung would be in the driver's side exhaust manifold. A reman computer controlled dist runs around $90-100. If you get into spending much more than that on the system you've got you may still consider the swap. Could probably glom a used computer dist cheap on these boards as well.

I recently converted one back to computer control. Had to rebuild the wiring harness cause it had been hacked off. For me it was worth the effort.

Checkerbelly

Thanks again. I thought it was a good thing that I had a mechanical carb and a mechanical distributor. What I don't understand is whether a mechanical carb can be matched up with a computer controlled distributor and vice versa.
Can I run my buddy's CCC carb on my car with a mechanical distributor or will it all go to hell in a handbasket?

Yeah, it has Headman headers. I haven't looked for the O2 sensor yet. I've blasted about a half a can of spray cleaner in and around the carb since those photos and it seems to idle a little smoother. Still bogs down if I push the pedal past a certain amount though.

I'll research the timing advance stuff and figure out what all this 18 BTDC stuff means. Remember, I'm new

I'll get down to the carwash pretty soon here and shine it up.

Here's the rest of the beast. And yes, the entire car was as grungy as the engine bay when I bought it.

Awesome-X

Looks pretty nice I really like the rims!

naf

iTrader: (7)

A Haynes or Chilton manual is a good thing for a beginner to have. It will walk you through a lot of the basic stuff with photos that a more thorough manual will assume you already know. BTDC-Before Top Dead Center.

Do a little reading up and come back here with specific questions. The best way to learn is to do.

G-4ce

iTrader: (1)

im not sure if im seein this right but it looks like one of the fuel lines are twisted at the bottom of the pic to the left of the carb

five7kid

iTrader: (14)

It sure looks twisted to me. The fuel line nut was turned without the inlet nut being held from turning.

The barametric sensor is visible in the engine photo, so it probably was originally a computer controlled carb.

naf

iTrader: (7)

...and the EGR valve appears to be plumbed straight into manifold vacuum. Disconnect that and plug that vacuum port-see how it does.

Checkerbelly

Hey guys. Well, I tried a few things. My girlfriend's dad told me to drive the car down the freeway at 4000 rpm for awhile and see if it starves for fuel. it didnt. But it sure did warm the engine up. (and once warmed up it had a LITTLE less bogging/stumble). It only bogs when I push the gas pedal down past a certain point.

I also tried disconnecting the EGR and plugging that vacuum line. No luck. Same deal.

I got to looking at the vacuum hoses and realized that it doesn't match up with the schematics for either the mechanical or computer controlled carb/distributor. It's kind of a hybrid of the two with hoses plugged into a canister control valve instead of the canister itself. And some of the TVS units are gone. The distributor hose looks like it's plugged into the left-hand side of the carb. I switched it to the right-hand side, like shown on the schematics, and it didn't seem to make a difference.

Anyway, I've got a bit of chop job here. I'm not sure what to do. I have no frame of reference because it doesnt match either the computer controlled or mechanical carb diagrams. Sorry to digress. here's some pics (at least it LOOKS a little better now):





see my twisted fuel line and vacuum distributor plugged into the left side of the carb The hose come from the distributor and connects just under the fuel connection of the carb.


This is a mechancial carb with a canister control valve. Doesn't match any of the standard schematics...


Right-hand side of the carb. showing some of the vacuum plumbing. My fingers are around the vacuum line coming from the canister. There is one more line coming from the canister and going back to the fuel tank (I think)

Checkerbelly

Here's another fun thing I discovered. A threaded hole in my engine. It looks clean like something was recently removed from it. Its to the right-hand-side of the carb. Any clue what it is?

naf

iTrader: (7)

We can help out with the vacuum routing, let me get some photos together and go over them. In the meantime you may want to disconnect and plug every vacuum port on the carb except for the brake booster, dist advance and PCV (make sure the little ball in the PCV valve rattles when you shake it) then give it a drive. You can even reconnect them one at a time while it's idling and sometimes be able to tell if one is leaking. Disconnect and plug the accessory vacuum port on the manifold rear of carb too.

A brakebleeder/vacuum pump can be 'rented' from Autozone or one of the other chains and used to test the integrity of each of your vacuum circuits. Use it to test the dist advance and brake circuits we had to leave connected earlier-along with double checking the others.

The purge doesn't look off but I'd have to compare it to another to tell for sure. The top port on the carb to the purge is the bowl vent and is not subject to any vacuum. There IS a line to the canister from the tank that collects vent fumes.

The bolt hole is for the brace that runs to the AC compressor bracket.

Checkerbelly

Cool, thanks a bunch! My main issue is just understanding what the vacuum line's functions are and where they are supposed to go. In the meantime I'll tinker with it some more and do some book-learnin.

I really appreciate the help.

Checkerbelly

I haven't tested vacuum lines yet, but I put in a new PCV valve. No real affect on performance there.

I got searching for the oxygen sensor and could NOT find it. I don't think it has one anymore. The previous owner installed Hedman headers and a Flowmaster exhaust. I got under the car and searched up and down to no avail.

Does a non CC quadrajet even need an oxygen sensor? I can't find an answer for that one.

DoubleV

Yes. In fact it's one of the most important ones. It senses how rich/lean your exhaust is.

Checkerbelly

Thanks. what happens with the signal from it? How is that signal used? I think a CC quadrajet uses the signal to control the primary metering rods, but a non-CC quadrajet?

five7kid

iTrader: (14)

A NON-cc q-jet does not need an O2 sensor.

///DAN///

iTrader: (1)

i don't see the kick down cable that should be there to tell the trans to downshift, which if indeed you are missing that it could cause some problems when you mash the pedal down.The empty bolt whole is for a air conditioner compressor support your compressor is gone so you don't need that. Hope this helped you out some .

Checkerbelly

every little bit helps! I'm a complete newbie.

It's a manual transmission. I'm guessing I don't need the kickdown cable.

G-4ce

iTrader: (1)

no manual does not...but if i remember right the kick down is done by vacuum

///DAN///

iTrader: (1)

sorry missed that it was a stick.Are you downshifting the right way when you mash the gas if you have it in 4th gear it will stumble when you mash it until it gets the RPM's up high enough. Silly question have you had any body else take it for a ride to see if not to be mean maybe you just need to get used to the shifting . Don't get discouraged I had a 83 monte carlo with a butcher 305 in it where all the emissions and vacuum lines were burned out it may take a while to get it straight but when you do it will be a fun car to drive.good luck

DoubleV

Hmmm. I obviously missed the 'non' part.......

naf

iTrader: (7)

A few thoughts:

Your EGR valve will not function correctly as it is connected and likely isn't functioning at all anyway. At this point I'd recommend capping the vacuum port to it and removing the lines.

The EFE valve would have been removed when the headers were installed. It was controlled by the TVS (thermal vacuum switch) on the water neck. Anything connected to that switch can be removed and the switch replaced with a threaded plug, if you want to go that far.

The plumbing for the evap canister looks correct. It should be controlled by the TVS in the manifold, up front by the water neck, and a vacuum switch. Check the condition of these lines, especially around the switch.

Your accessories are plumbed from the vacuum source on the manifold behind the carb. You don't have cruise so your vent doors for your ventilation system should be the only thing using this source. The line runs to the vacuum reservoir under the evap canister up front, driver's side. This provides enough vacuum to keep the vent doors in position during short, low engine vacuum spurts. A vac tester connected to the line at the port may take some pumps to show a drop because of the reservoir.

The vacuum port near the top of the carb that is plugged with a short piece of hose provided vacuum to the stove pipe on the stock air cleaner. It provided air to the cleaner that was preheated by exhaust manifold heat during warm up. The diagram will show it running to a little TVS that was in the air cleaner. You can pick up a proper set of vacuum caps from the parts store and cap that line.

Your ECM is no longer controlling anything. It resides up under the pass side hush panel. The ECM wiring harness can be removed in it's entirety (don't hack it) by pulling it through the pass side fender and unplugging it from the ECM. There is the slight chance that your car was fitted with an in-tank helper pump that could still be receiving a signal from the ECM. If so it would have an oil pressure switch (2 wire) in addition to the oil pressure sender can (1 wire) behind the distributor. In 85 these should only be on L69s which also came with electric fans, so I doubt it's there.

Checkerbelly

Hey guys. I did something drastic. I started out by replacing vacuum lines, plugging the EGR and trying to adjust my carb. Well none of that helped the bogging issue. So I went to JEGS (local to me) and picked up a remanufactured Quadrajet (non CC, electric choke). They make ones that are mostly tuned for your specific car. I put it on my car and put a block-off plate over the EGR mount. What a difference! The car accelerates smoothly now no matter what throttle position. It feels like I have more power off the line, and generally feels like a new car.

The only issue I have now is the idle. It started out idling at 2000 or 2500 rpm when I first fired it up. While the car was running I went over and tapped on the linkage on the passanger side of the carb with my finger between the carb and the choke, and something moved, and the primary air plate opened up a bit, and the idle went down to 1,000 rpm. Starting and stopping the engine after that I had an idle that sometimes was 1,000 without tapping on the carb. Sometimes bouncing around between 1,000 and 600.

Anyway, I'm at the point now were I have to go out and tap the linkage with my finger to get it to a decent idle speed after a cold start. I think it has something to do with the high idle kickdown whatchamacallit getting hung up on something.

Anyway, I thought this was good news. I know a new carb isn't the best prescription, but I just wanted to try installing it. So far it seems to be working out well.

note: I blocked off the EGR because it interfered with the chrome valve covers from the previous owner. He had put 2 spacers under the valve mount in order to clear the valve cover and I didn't want to screw around with replacing that mess. I'll probably buy an EGR in the future and look into mounting it back up to see if it does any good.

naf

iTrader: (7)

Did the reman come complete with choke? Sounds like it's getting hung up on the fast idle cam that engages when the choke is closed. Even after the choke opens it the throttle will stay on this fast idle stop until the throttle is opened enough to let the fast idle cam drop away. Look at it and fiddle with it some and you'll see what I mean.

Also make sure your choke wire is connected. The choke should be closed when the engine is first started cold then slowly open as the engine runs. After a few minutes the choke blade should stand straight up and allow the idle to drop back down off the fast idle cam so it can be controlled by the idle set screw on the opposite side.

Checkerbelly

Yeah, the carb has an electric choke. And I know what you mean with the cam getting hung up. I talked to JEGS on the phone (EXTREMELY HELPFUL!) and turned the choke a little to loosen it up. It worked, for the most part. I think I need to turn it a little more because it still revved high this morning.

Anyway, once I get that settled I can work on my idle. Right now I think its rich. There's white/gray smoke coming out the exhaust only at idle. And my tach bounces around from 1,000 rpm to 800 rpm. From what I understand the idle adjustment is an idle speed stop screw on the drivers side, and two screws or tabs located in holes at the very bottom front of the carb. I'll be getting into those next.

89RsPower!

I didn't read all the way down so Im not sure if anyone answered this already or not but it does matter which carb you have with which dist. If you are running a non cc carb you should also be running a non cc (vac advance) dist and the other way around, you should be running a cc dist with a cc carb.

naf

iTrader: (7)

He's good with the vac advance dist.

The idle speed set screw is under the throttle arm on the driver's side. The idle mixture screws are bottom front. Looks like the tamper proof plugs have been removed already so you're good there. Make sure your timing is set in the ballpark of 12+ degrees base (with vac line disconnected from the dist) and make sure the timing is advancing to around 32-36 degrees at 3000-3500 rpm. You may not be able to tell exactly where it's at as the timing marks won't go that high but the important thing, now, is that it IS advancing and by approximately that much.

Adjust your idle mixture screws evenly (same number of turns on each) to get the smoothest/fastest idle or the highest vacuum reading. This should get your carb, at least at idle, in tune.

If it's still noticeably running rich off idle you may consider a re-build to include epoxy of the well plugs, which tend to leak fuel as they age. These can add unmetered fuel into the manifold, especially at higher manifold vacuums.

Play with your idle mixture screws after verifying timing and see where you're at.

Checkerbelly

Well I bought a timing light and it didn't work. I don't know if it was defective or what. So I finally got around to adjusting the idle mixture screws and had no success.

I tightened the screws all the way in. No change. Still idling rough around 1,000 rpm. I backed them each out about 5 turns, slowly. Idle slowed down to about 900 or 800 rpm and put lots of smoke out the exhaust. Still rough.

My guess is that there's either air or fuel getting in where its not supposed to. If I put my hand over the primary air, the car dies.

If I have the idle mixture screws mostly IN, and open the secondaries a crack with my hand, the car slows down. If I do the same thing with the idle mixture screws backed out, the car speeds up.

But I bascially couldn't get the car under 1,000 rpm. The big screw on the drivers side that holds the throttle linkage is backed out all the way.

Checkerbelly

UPDATE:

Well I exchanged out for another quadrajet carburetor rebuilt by JEGS. This one idled well, but didn't drive so great so I took it to a mechanic that said the accelerator pump was not working correctly and a couple of other things.

So I bought a remanufactured carburetor rebuilt by Holley. Put it on last night and it runs great! Idles well and the car accelerates smoothly and seems to have a lot of power.

Soooooo lesson No. 1: Pay the extra $50 for the nicer rebuilt carb.

naf

iTrader: (7)

I've seen a lot of carb issues from guys that have recently purchased and installed a rebuilt carb. It's hard to find fault with a carb you just spent ~$300 on. Did you send the bad one back?

By the way, I'm kinda digging the old style wheels. 15"ers?

Checkerbelly

I'm local to JEGS so I'm going to drive it back. The mechanic that looked at it for me said if JEGS gives me any trouble - tell them to call him.

I believe the are 15". The rears are wider than the fronts though. I'm having very little luck finding tires that come in the sizes I want. I've gotten a couple of compliments on them. I guess some locking lugnuts should be my next purchase