| First, a note
on my experiments with the self-made intake. During last winter, I
reduced the size of the plenums by molding some epoxy on the plenum
floor. This appears to be a change in the right direction, as it
stopped popping in the exhaust at low rpm's, and idle isn't so shaky
anymore. I also roughened the surface of the epoxy, to avoid fuel
dropout. If you look at the plenum floor of any V-8 intake, you will
see that the floor is heavily textured. The engine still isn't too
responsive to the throttle, and needs full accelerator pump shot from
both carbs. I think I could yield further benefits from filling the
plenums even more. My basic design "error" was the plenum design. The
fact that one carb only feeds 4 cylinders now, slowing down the flow in
the carb, makes it even worse. So, anyone who's going to build a
multi-carb intake, would better avoid excessive plenum areas, and try
to arrange a progressive setup, so that only one carb feeds all
cylinders at idle, and other carbs step-in later. I have always been fascinated about constructing an EFI system on my Cobra, to yield better drivability, mileage, and tuneability. A friend of mine, Anssi, who built a Cobra much like mine, talked me into group purchasing DIY EFI kits, namely the Megasquirt. In Finland we have a forum just for Finnish Megasquirters. Megasquirt supplies the PCB (Printed Circuit Board), PROM chip, and MAP sensor, while you can download the schematics and instructions from their website, and purchase all other components locally. Also, you'll have to fabricate all hardware yourself. So I let my buddy try it out first, and his setup has worked great for over a year now. I cooked the engine of my Cobra a long time ago, and it needs a complete rebuild. But, I decided to try the Megasquirt on my Buick! Somehow the idea of adapting EFI into an ancient engine just thrills me! It's like Jurassic Park come real. While I was still working for GE last winter, I modified the intake manifolds to accept 4 fuel injectors. I also prepared a few other things as you will see. Due to lack of time, I am not going to finish the EFI setup this summer. I'm just going to drive the heck out of my Buick. Update 2008: After consulting people who have tried a batch-fire EFI on a Buick-8, I'm having second thoughts. It seems like the siamesed intake runners require a sequential-fire EFI, to avoid mixture variations between cylinders! |
 Mark Sanders gave me some stainless nipples that are presumably intended for a Ford (USA). I appreciate it - thank you very much! These nipples feature a clever lock plate that keeps the injector in place. The nipples can be seen here welded in place. The same nipple can be used on the fuel input side as well. VERY NEAT ! Being located far away from the intake valve, the injectors act more like a TBI system rather than EFI, except that the injectors are located below the throttle blades in this setup. Kimmo, one of the members of our "group purchasing gang", handed me some leftover Bosch injectors, which served as mock-ups. They might even be suitable for the actual job, but I haven't checked their flow rate yet. |
 Here you can see how I molded the plenum floor with epoxy, and once cured, opened up a path for the injector squirt, by rotating a drill bit through an arc. Also note the texture that I scratched on the epoxy. IIm going to use the existing Strombergs as Throttle Bodies! While not the most optimum solution, they will retain the old appearance, and should the EFI system give me fits, I can always convert it back to old fashion yet reliable carbs. |
 The mandatory Intake Air Temperature (IAT) sensor is a standard GM part, installed through the air cleaner base. The computer uses the information from IAT sensor, Manifold Absolute Pressure (MAP) sensor, and engine RPM, to define how much oxygen the engine is breathing. This kind of system is called "speed density" system, while the other alternative is the "mass airflow" system, commonly used by the OEM's. The mass airflow system uses a Mass Airflow Sensor to measure the actual amount of air entering the intake. The MAP sensor came with the kit, and is mounted on the PCB. So you'll have to run a vacuum line from the intake to the controller module (ECM). The other sensor here is the Throttle Position Sensor (TPS). It is not mandatory but advisory. The computer uses its input to determine if you are accelerating or decelerating, enrichening the mixture or cutting it off, respectively. I removed the starter switch from the other carb, to reveal some throttle shaft, and mounted the TPS sensor in place of that switch. |
 I drilled and tapped a hole in the water neck for the coolant temp sensor, which is also a standard GM item. The ideal location for this sensor would be in the head, but there's no extra holes in the Buick head available. The controller uses the input from this sensor to determine the need for extra fuel (choke) during cold starts and warm-up, as well as the need for additional air (fast idle). I am not going to use any valve to feed extra air. Instead, the fast idle cam on the Stromberg will take care of it. |