I figure since I’m here on the forums and play enlisted a lot, that I’d start documenting my 1978 Omega car project. I guess I’ll just use this as a journal for stuff done and issues I’ve run into. It may be useful for someone, who knows. Anyway here goes what I got.
I bought this 1978 Oldsmobile Omega for $8,300 from a minister who fancies modded cars. It has a brand new slightly built 350 small block engine with high rise cams, forged internals, and long tube headers. The body is 90% stripped. Transmission is a Turbo 350 with a ratchet shifter, 4.57 gear rear end, drag radials, and Jegs torque bars. All the electrical is analog controlled by switches installed on a switch board on the dash.
Upon picking this up, the alternator would not charge the battery. After troubleshooting for several days, determined that the #2 wire for the alternator, which is the voltage regulator wire, was wired backwards through the ignition. The easiest fix without rewiring everything was to run the ignition wire to a stand alone toggle “on, off” switch. After that repair, the alternator was charging the battery.
Next issue was while driving. When the throttle was pushed down hard, the engine would backfire and lose power. There was a small pool of fuel on the intake manifold. The damaged part was something called the accelerator pump located on the bottom of the carburetor. This is a small rubber diaphragm pump that pushes extra fuel into the carb when you step on the throttle. This part was bad and leaking, causing the carburetor to run very lean when you stepped on the throttle which in turn caused the backfiring. This part I just replaced tonight July 16 2022. After testing, it resolved the backfirong issue.
Note my carburetor is a Demon 750 double pumper. If you have a carb that is a double pumper, you will have 2 of these accelerator pumps. Make sure that you order 2 components and not just 1. Learn from my mistake.
Anyway the accelerator diaphragm pump is held in with 4x Philip’s head screws. Remove those and you can remove the cover plate and lever. Under the diaphragm is a spring, leave the spring there, don’t lose it. Place the new diaphragm on over the spring and reinstall. Done.
Next problem. The engine runs hot, like very hot. The OEM radiator will not suffice for this engine. Replace with a new polished aluminum radiator, I got mine from Summit Racing. I have not installed it yet, so that will be another update.
