I just got my hands on an 85 Camaro Z-28. Was told it has a 350 motor and a TH350 trans. Was NOT told what kind of carb. Supposedly previous owner to previous owner etc. swapped the motor. Anyhow, it won't idle high enough to stay running unless the heater is off and it is nice and toasty. Have to keep playing with the throttle to keep it going. Since I don't know what kind of carb (but I can at least tell it's a carb) I have, can someone help me with that? I think the 350 motor is right because (please don't groan) it looks like the one in my mom's Tahoe except with a carb and different intake. Where exactly can I find the casting numbers to acertain if this is true? If it is a 350 (emissions sticker and vin say it was origionally a 305) how can I tell what wiring harness, computer, etc is in my car? I currently have a check engine light on (P.O. says it was always on) and when I first start the car I have a light showing "CHOKE". I'm guessing this means whoever swapped the motor retained the origional carb and electronics. HELP!?!?

 

You've got a lot of problem variables there, but everything pretty much points to the carburetor. Quite sure your car has an electronic mixture control soliniod(M/C) Rochester 4 barrel. If the engine is different than the stock carbs calibration, who knows how she'll run. Also Quadrajets have some well known problems. The most common being internal leaky pressed in fuel well plug seals. Also the M/C solinoid rubber metering tip can break off over time. Both of these are quite easy to fix, but the M/C soliniod isn't cheap. Doesn't sound like you're much on auto repair, so it's repair shop time. There's a pretty good independant shop on Hoover & 14 area, but can't remember the name. Another option. A guy called Lar's(larstune) travels the country and holds older car tune up seminars for $150. He supplies the knowledge and parts, with you doing the actual work. Mostly for older muscle cars, though. Not sure if he does M/C carbs. For $150, it's worth looking into.

 

305's and 350's look identical, along with every other gen 1 small block chevy. Can you post a picture(preferably a good one, not a crappy camera phone pic) of the carb with the air cleaner off? There are so many variations of so many different carbs that a picture is very useful, as are any numbers stamped/cast into the carb.

There should be a pad behind the alternator with some numbers stamped there, they'll be gone if the block was decked though. They can be VERY hard to read sometimes. If you can't find those look behind the drivers side cylinder head, if it says "5.7" it's a roller cam 350, if it says "5.0" it's a roller cam 305, if it just has a long number it's a flat tappet block and we'll have to look the number up. It would also be helpful if you took off the valve cover and got the casting number of the head. www.mortec.com is the best website for chevy casting numbers.

How many times does the transmission shift when it's in drive?


If it has a not working CC-Qjet, personally, I'd replace it with just about any non CC carb.(assuming you're not in cali or some other state with ridiculous emmisions laws) Do you have the stuff to check ignition timing?

 

I don't have a camera for the carb pics, I don't have the equipment to check the timing. I'm actually half decent with mechanical, but this is my first chevy and first carb setup so bare with me. I will get to the numbers on the motor and see if I can identify the carb some other way and get back to you guys.

 

Look for an electrical connector on the carb, I believe it's 4 prongs.

 

Between me and some of my friends (one ASE mechanic), I have a 350 motor, my timing was adjusted slightly and now it idles better, but still occasionally stalls, and the idle is still erratic. I have the original rochester carb, I'm guessing it is similar if not the same one that was on the original 305. With the timing adjusted the engine performs better, but between the three of us we believe that there is not enough carb for the motor. Any other ideas of what could be hampering performance?

 

A stock or near stock 350 will run fine with a 500cfm carb, as far as idleing. If its a quadrajet, its more than enough carb, you can be sure of that. That being said, when you set the timing, how did you go about that? Does the carb have an electrical plug on it? If so, what does the distributor look like. You may have he wrong distributor for the carb. They must either both be CC or non-CC.

 

As mentioned earlier in this post, you've possibly got something internally wrong with your carb. This forum has a pretty good carburetor section. Probably worth a look.

 

We set the timing by ear, just slowly rotating the entire distributor assembly with the car running until the idle smoothed out. None of us could find timing marks. The carb has several "slide on" electrical connectors, and several vac lines. The distributor had a 4 prong connector that mated with a harnes that disappeared into the firewall, and three press in connectors on the drivers side of the distributor. On that was approx, 4cm wide, and then two that where half the size.

 

hmmm, sounds like you have a CC distributor in the car. If you are running a non-cc carb, you are fighting a losing battle.

 

How can I tell if I have a CC carb?

 

if it has a lot of wires attached to it, it CC, if it has one wire for the coke only, then its a non-cc

 

There are at least three wires that I can remember off hand. The carb has "Rochester" stamped into it.

 

this picture is a representation of a standard rochester, its not necesarily the same as yours.
Your carb if its a CC qjet will have a MCS solenoid on it, with a plug that attaches to it.

 

That carb looks nearly identical to mine. Except mine has a single prong electrical connector in front of the linkage that is connected to a harness linked with emissions equipment.