My Greenbrier '64 has a nasty habit of stalling when I am waiting for traffic lights. The engine is in quite good condition with refurbished carburetors. Everything tuned according to section 7, engine-tune-up. I have an electric fuel supply system with pump in tank, and a pressure regulator in a return line to the tank. System pressure is set at 3 PSI. I have had it at 6 PSI but the problem stays. I am not quite sure about the condition of the distributor, cables and coil but the spark plugs look fine and I have sparks on all distributor terminals. Car starts perfect and runs fine, sometimes with a hiccup but always that stalling on very, very inconvenient moments.
But now I found something that puzzles me. If I disconnect the spark plug cables on the right side of the car (nrs. 1-3-5) one after the other, each disconnected wire causes the engine running irregular. If I do the same at the left side of the car there is no effect at all. Even with 2-4 and 6 !! disconnected at the same time. The engine runs moderate with a to my idea somewhat sluggish reaction on the gas pedal. Although to my knowledge. Maybe I have never heard this engine running with six cylinders. But is it possible to drive a Corvair on just cylinder 1-3-5? Could it be that the engine runs fine with 6 cylinders at speed and falls back to 3 cylinders at idle? Anyone with a clue is my hero.
Could it be that the engine runs fine with 6 cylinders at speed and falls back to 3 cylinders at idle?
It could be as simple as mixture adjustment and synchronization or that carburetor's idle passage could be clogged. I had a main jet plug up once. You could also have a stuck float. Anything that restricts fuel on that side can cause your symptom.
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It is not uncommon to discover that your Corvair engine is running on six but idling on three. The Rochester HV can be suffering from clogged idle circuit fuel passages on one carburetor only — leaving one bank of cylinders running on air while the opposing cylinders do all the work in keeping the engine spinning at idle. The idle speed adjustment is simply cranked up on the side that is getting fuel at idle to compensate for the dead cylinders that are starving on the other side. Since many Corvairs have both exhaust manifolds combined into a single muffler on one side, the difference in exhaust sound when listening to the left vs. right side is hidden. You discovered the absentee bank of cylinders when you disconnected the spark plugs on one side at idle — only to discover that the missing cylinders had no impact on the engine at idle.
The faulty carburetor likely has a full float bowl, but its contents is not contributing to the job at idle. You will likely have to disassemble the carburetor and carefully soak the faulty carburetor body in carburetor parts dip and then flush out the fuel passages with water and air pressure to hopefully clear the way for the missing idle circuit.
The attached booklet, DELCO ROCHESTER - Models H, HV Carburetor Service Manual, has an informative opening section that carefully describes the differences between the idle circuit and high speed circuits, which will help to explain how your engine power returns with an open throttle feeding all six cylinders, but at idle three of those cylinders likely go to sleep.
- DELCO ROCHESTER - Models H, HV Carburetor Service Manual.pdf
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Lake Chatuge, North Carolina
1966 Corvair Corsa Convertible