Swapping from EFI to a Carb in Camaro or Firebird

Parts required:

• Carburetor
• Carb intake manifold
• Non-computer controlled distributor (complete)
• Either:
  • 3-port AFPR and fuel pressure gauge
  • A carb fuel pump and in tank pickup
• A set of intake manifold gaskets
• Some small pieces of sheetmetal
• A throttle return spring and bracket
• Assorted nuts/bolts, brass fittings, hose clamps, etc.
• A good set of mechanics tools
• Some basic knowledge and skill working on cars

WARNING: I am going to assume you know how to do basic modifications like remove and replace a Firebird’s or Camaro’s distributor and intake manifold. If you do not, there are other Firebird and Camaro articles devoted to that, but I would suggest you reconsider doing this swap. It is easy for a somewhat experienced amateur, but would not be advisable for a novice.

The first thing you will need to do is remove the old fuel injection system from the intake manifold up. On a Firebird or Camaro TBI, this if very easy, TPI takes a bit more. Once you have it off, clean the surface of the heads and lifter valley edges of all gasket material, taking care that no debris falls into the lifter valley or down the ports. I stuff rags in them to be sure nothing gets down there.

Install the carb intake manifold. As for choosing which manifold is best for you, that is largely a matter of personal preference. Most likely you will want a dual plane such as an Edelbrock Performer or Performer RPM. Personally, I used a Wieand Stealth, and am very happy with it. Most likely, your car is equipped with 87-up cylinder heads (in other words, your car is a 1987 or newer). If you look in any performance catalog, you will see that most manifolds are offered in both 86-earler and 87-up options, and the 87-up is always a lot more expensive. EITHER one can work for you. The only difference between the two is the angle the four middle bolt holes are drilled at. To use an earlier manifold on later heads you must simply elongate those bolt holes (in the manifold) a bit with a dremel tool or die grinder. A dremel bit chucked into a drill would even suffice. This is what I did, and it was much cheaper than buying the prescribed manifold.

The next thing you’ll want to do is drop in the distributor. There are basically 3 options for this, junkyard, remanufactured, or an aftermarket. GM used the one you need from 74 to around 83 I believe. I used an Accel aftermarket one. It needs to be complete with the Firebird or Camaro ignition module, wiring harness, cap, rotor, and coil. Drop it in the engine, being sure to get it on the same tooth as your old distributor. The old coil has 2 wires going to it, you will need to connect these wires to the connectors on the new coil. If you can find the proper plug assembly in a store or junkyard for it then great, I simply used two crimp on female spade connectors to clip them onto the new coil. It will have only 2 connectors to go to, the red/pink wire goes to the one labeled BATT, and black wire goes to the connector labeled TACH. Connect all spark plug wires, being sure to get them on the right terminal and in the right order.

Next, install the carb and gasket on the manifold, and tighten the bolts to spec. Be sure to install the throttle return spring in the most convenient place (mine is under the rear drivers side bolt that holds the carb on), so it keeps tension on the throttle at all times. The linkage will take some fabricating on your own to get to fit properly. On TBI models, this is fairly easy, what I did was take 2 small pieces of sheetmetal, about .5" wide by 1.5" long, and drill small holes in both ends. I used small bolts to attach one end to the carb, and the other to the throttle cable and TV cable. The TV cable snaps over the head of the bolt, while the throttle cable has a hole already drilled in it. For TPI, I’m afraid you’re gonna have to figure that out on your own.

Connect all vacuum hoses. As you probably used a vacuum advance distributor, don’t forget the one that has to go from the distributor to the carb. Most carbs have a timed vacuum port designed expressly for that purpose, consult your manufacturer. My Holley has a port in the passengers side of the primary metering block. Also, be SURE not to forget the vacuum line to the power brakes. I used the PCV port on my carb for my brakes, as I also replaced my PCV tube with a breather. Every manifold and carb is a little different when it comes to vaccum ports. Just use common sense when routing the lines. Double check to be sure that all vacuum lines are intact, and that all ports on the carb are either used or plugged. Carbs don’t like vacuum leaks very much.

Finally, you will need to route fuel to you new carburetor at an acceptable psi, for a carb, that means 5-8 psi. There are two ways to do this. The first is installing a 3 port, return style AFPR inline before the carb. The second is to install a carb fuel pump. Both options will work, and cost about the same. The AFPR is much easier to do, but the aftermarket fuel pump is probably better in the long run, especially if you plan to go to a bigger motor later that the stock pump won’t be able to keep up with.

AFPR option:

There are two AFPRs at the time of this writing that I know of. One is made by Mallory (p.n.: MAA-4309) the other by Barry Grant (p.n.: 132-171021). Again, which is better is mostly personal preference. Note that there are three lines from the fuel tank on the drivers side under the master cylinder. One is fuel delivery, one fuel return, and the other goes to the charcoal canister behind the headlights. The fuel delivery line is slightly thicker than the return. Go to your local hardware store and buy some 3/8" pipe thread to 3/8" hose nipple fittings, and put one in each port of the AFPR with a good coat of thread sealant. Plumb a hose from the fuel delivery line to the suitable port on the AFPR, and do the same with the return. Finally, run a line from the pressure port on the AFPR to the carb. Remove the hose that’s on the line going to the charcoal canister (remove the whole canister if you want), clamp a length of 3/8" hose onto the end of the hard bent line, and rout it out of the engine compartment somewhere. Mine exits in front of the left tire. This is necessary to vent pressure buildup inside the tank.

Firebird or Camaro Fuel pump option:

This one requires dropping the fuel tank. You must replace your stock in tank fuel pump with either a carb pickup from an older carbed f body or simply a section of hose. A good pump to use is the Holly Red or Blue in-line electric pumps. Install it according to the included directions.

Other things you should know. Your SES light will come on, and stay on. Since it no longer controls anything, it means nothing, ignore it or remove the bulb. Also, if you have an automatic, the computer will no longer lockup your torque converter. All this means is that you will lose a little gas mileage when cruising in 4th gear over 35mph. You can either live with it, rig your own lockup switch (see the article in Tech Central), or there is a kit available that will take care of it.

Well, you’re almost to the moment of truth. Double check all connections. Make sure your lines don’t leak. Now, crank her over. If you did everything right it’ll fire right up and purr. The first thing you should do is set your timing, then start to tune the carb, but that is a whole other article. Go under your passenger side dash, pull out the ECM, and remove it. Start a bonfire, get naked, have some beer. Throw the ECM in the fire, dance around it and chant, for you have just joined the world of raw, primitive POWER!!!!