I have asked this on Oldsmobile specific boards and I haven’t gotten a response yet since those boards are slowing down lately.
I took my 72 Olds for a trip down the 1/8 mile drag strip recently. Now, the times are not great and I believe the problem is fuel related. About 1/2 way through 2nd gear the car feels like it runs out of fuel, RPMs drop off. Let off the gas and then kick again it pulls on through the rest of the track. This motor has 5Kmiles on its rebuild. The carb has about 500 miles since it was last rebuilt following a book from Cliff Roggles (probably spelled that wrong) specifically about Quadrajet carburetors. The one thing I cannot remember is fuel inlet seat size being measured.
The engine is in a completely restored car. New fuel tank, new hard and soft (fuel rated) hoses from tank to carb.
4 areas of concern for this:
- fuel pump to weak to provide the flow required due to possible damage from having the fulcrum under pressure against the cam button for about 6 years before the engine was ever started or from just a too low GPH rate for this motor
- the inlet diameter on the needle and seat not large enough to support the amount of power this car makes. Some gains over stock but by no means a race car, the Qjet book talks about this being a big restriction on these cars
- I run a 71 fuel filter style system. This has a diverter valve for pressure relief in the fuel filter that dumps back to the tank. I am concerned this is dumping too much pressure under load, suggestions have been made to clamp off the return line but I am not sure if it will blow the needle off the seat because of straight pump pressure. I can try this soon
- Sock in the tank getting uncovered and just sucking air under acceleration. I have done hard acceleration testing in this car with varying levels of gas and I don’t remember this making a difference. This weekend it did feel like it fell off sooner in RPM on the second run than the first with a better 60 ft time leaning towards a tank pick-up issue possibly.
I want to fix this because it is not a good idea to run a motor out lean under hard acceleration. That is what this car was build to do and needs to be able to do it. Anyone seen and fixed something like this problem?