I have a 1978 vette with the L82 motor and I am planning to rebuild my carb. This is my first attempt at this so before I start this project, I would appreciate any advice from anyone who has done this. Any recommendations on a rebuild kit? I saw one on Ecklers that looks pretty good.

 

There are a couple of How To Rebuild Your Quadra-Jet books. Buy one.

You can possibly get your rebuild kit from AutoZone, NAPA, or other geeric auto parts places.

 

How much time should I allow for the project?

 

If your carb is original to the car...and you don't intend to rebuild any other Q-Jets...you can save the money on the books. Just go to NAPA with the numbers that are stamped into the left-rear corner of the carb. Tell them you want an Echlin rebuild kit for that carb and you also want a new Nitro-Fil float and an accelerator pump with a Viton seal (tolerant of Ethanol). {Unless they can assure you that the accel pump in the kit has the Viton seal, buy another one which does.}

The rebuild kit will have instructions in it, along with a diagram of the carb parts. Read through the instructions thoroughly, AHEAD of doing the job, so that you know what is involved. It would be good if you purchased a gallon can of carb cleaner (with parts basket inside), so that you can do a good job of cleaning the parts. It would also help to purchase a pressurized can of air (or other non-toxic gas) so that you can blow out the passages in the carb [assuming that you don't have an air compressor in your garage].

Take your time as you disassemble the carb and take digital photos to assist in the reassembly. These are particularly valuable with the choke assembly and secondary linkage. A few photos of the carb as it sits now will help considerably.

Keep all parts/gaskets that you remove. The kit comes with several gaskets/seals and you MUST use identical parts as removed with new replacements. Parts with minor differences can have very negative effects. Take time to be certain of the replacement parts you select.

It is best that you DO NOT paint carb parts to make them look 'better'. It can be done, but do it wrong and parts don't work properly. It's best just to clean everything with a stiff brush (non-metallic) and let it go at that.

The only difficult part of reassembly is the choke rod link. It is hidden down in a 'well' and is difficult to keep oriented at the same time you are trying to engage it. Stay patient and you will eventually get it assembled. Use a light to make sure it is correctly assembled when done.

Good luck!! [This being the first time....allow the whole day to complete this task.]

 

7t1's instructions/advice above are pretty good.

NAPA is the only store I know of that's backed by any of the Top 3 (Lars/Henry/Cliff). Personally, I go with Cliff's kits (Cliff's High Performance, search for it) as he sells some really high quality stuff and will also help you out should the need arise.

The primary metering rods are also a difficult spot in addition to that choke link. The metering rods need to be resting inside the jet well and then a plastic collar on the power piston shaft staked in place. With the big float cover on the M4Ms it can be a little difficult to see the rods. Once you have them in the hole, you should be able to cycle them up and down with your finger with light effort. Make sure to catch them on the way back up; the collar can come loose as the act of the metering rods returning can act like a slide hammer on it.

In regards to the choke link, I find it easier to put the choke link on before the air horn is on.

For tools, I recommend:

• 1" wrench: for holding the filter nut while you remove the fuel line. Remove the filter nut after this. You need a 1" wrench as a slip jaw wrench will be too big to fit between the nut and carb body.
• 5/8" line/flare wrench: Used to remove the fuel line and the power brake line on the back of the carb.
• 3/4" line/flare wrench: used to hold the 1/4NPT adapter that the brake line attaches to while you remove the brake vacuum line.
• 3/16" flat head screwdriver (for some of the smaller screws)
• 1/4" screwdriver: for some of the larger screws, jets, and accel pump check ball retainer.
• 3/8" screwdriver (I believe) for removing the stock float needle seat.
• Drop calipers or a machinist's scale for measuring float height. The kits do include a measuring stick typically, but I prefer the other tools.
• Phillips screwdriver(P2): some QJets use these on the bottom of the carb to retain the throttle body to the main body.
• Long needle nose pliers: Helpful for lining the jets up, the check ball retainer and removing the 2 screws inside the primary venturi when you inevitably drop them.
• Small allen key set (1/8" I think is the one needed) used to loosen the set screw on the secondary air valve spring.
• Small flat head screwdriver: not sure the size (a jeweler's set should cover this) used to hold the secondary air valve tension screw and adjust it.
• A pick: can be helpful for extracting stuff that gets dropped in one of the carb venturi.
• Carb cleaner
• Shop towel
• Lots of gloves
• An aluminum cooking pan: the gallon of carb cleaner likely won't fit anything but the QJ small parts, so I dump the stuff in the pan and then put the big parts in the pan.
• Eye protection, particularly during the compressed air part.

I'm sure I've forgotten something.

I highly recommend Cliff's book, it's a small investment and has some nice helpful pictures to get you going. A supplement to the stuff supplied in the rebuild kit instructions.

Lars's writeup on QJet tuning also has some helpful hints for getting the airhorn off and calibrating the choke system afterwards.

Good luck. I can help out later when the time comes.

Also, here's two galleries of some carbs I rebuilt so you can get an idea what you're in for:

http://elucidus.smugmug.com/Car-Proj...0424&k=bw55Dtp

http://elucidus.smugmug.com/Car-Proj...5124&k=B6vb9FJ

 

Carb kits on various cars usually say to open the idle mixture screws 1 & 1/2 to 2 turns. It took 6 turns out on my 79 Quadrajet to get it to idle well and it idled a little better yet at 8 turns out.

 

I'm about to start a Q-jet rebuild myself, so I will watch as you progress. I actually have 2 carbs, one on the car and one in a box to practice on. Have Cliff's book and kit, and Lars "tuning paper". Also FSM, though it isn't a whole lot of help, IMO. 1975, manual, L-48, power, AC.

 

Get Cliff Ruggles(sp) book and Lars' tuning papers. You may also want to purchase a set of pin drills in the 65 thru 40 size, and use them to freshen the small apertures in the carb. There are other item to watch for such as, the staked screws retaining the butterflys and bushings for the primary shaft-all items mentioned in Cliff's book. If there's any rust on the carb, get some Evap-O-Rust form Harbor Freight and soak the entire carb in it. Wal-Mart sells aluminum baking pans that are 10"X10" and about 3" deep and come with a plastic top that are excellent for soaking the carb. If you have any questions, post here or contact Lars at v8fastcars@msn.com. He's a real gentleman and always answers questions sent to him.

 

Take lots if digital pics, don't worry about the carb being camera shy. Take it apart and reassemble before shop rot takes place or your memory fads. Use the plastic straw that comes with the cleaner to spray into the small orifices to make sure that they are clear.

 

Lars posted this in January about a 78 L82 (post 3):

http://forums.corvetteforum.com/c3-t...et-gasket.html

Only difference is I think he meant Napa crb-25795a instead of 995 which I could not find. But the store will narrow it down for you.

 

If you are working on the car's ORIGINAL carb, you don't really need those books. They ARE good books if you are modifying the Q-Jet carb. But, if you don't intend to change any air bleed hole sizes, jet sizes, rod sizes, etc. (assuming they were set properly by the factory), you don't need all that information.

If you want to learn about Q-Jets...go for it. Otherwise, it will be a $30 investment that you will gain nothing from [for rebuilding a factory-original carb].

 

If you pay close attention you don't need the instructions in the rebuild kit either. When you forgot to take one important picture though, it's nice to have a few backups.

Odds are if the carb IS original and he's in an area with ethanol gas that a little tuning wouldn't hurt.

 

Odds are you could tune your carb enough to keep the engine running, not well but running, knowing nothing about it.
Better is to know how it works and thereby how to tune it properly for best operation.
Sure you can take it apart and put it back together, monkey see monkey do style.
If it were mine I would prefer to know what I could to get it to run the best I can for my application.
The knowledge in this book is worth far more than the $17.56 you'll pay for it.