I want to thank all for the help so far on my new baby. a 1930 Roadster. I've owned many an old car, truck and motorcycle, but this is my first old Chevy. There are a few mysteries I'm curious about.
The metal tube coming from the oil fill tube. Is that some kind of breather for the crankcase? If so, it doesn't (on my car) extend below the frame like most do and if it is a breather, can I extend it as it seems like the oil smell is being directed basically into the cab. Not a nice odor as we all know. In the owner's manual, it says it's some kind of what we call, a pcv valve, but the one on my car is not attached to the manifold. It's curved down to the catch-all panel below the carb.
On the carb, the lean/rich large adjusting screw....the car when I got it was burning very rich as the plugs were very sooty. I turned the adjustment in all the way and out about 1 and a half turns. Hoping that should do it.
Last for now, the old gentleman said he had disconnected the spark advance, but it looks to be connected but froze in its cable. He's been running the car for a few thousand miles, after a complete rebuild, with no apparent problems. I know from owning a Model A you have to adjust the spark while under load. This set up, while froze is at least in full retard position, so no kick back at start up. Should I try to free it up or leave it, as I didn't notice a problem either, when I drove the car?
Oh.....and I assume the hub caps just pop off the rims? One is a bit loose, and I want to try and secure it tighter so It won't rattle around.
The metal tube from the oil fill tube is indeed for crankcase ventilation. It should connect with a port on the air cleaner so fumes are directed into the carburetor.
The large spring loaded screw adjusts the amount of additional air that blends into the air/fuel mixture drawn up the low speed jet (aka idle tube). If there is little change in idle speed when adjusted from closed to 1 1/2 turns open there is a problem in that circuit. The majority of used carburetors have the screw closed to only slightly open, primarily due to wear on the throttle shaft and carburetor body. As long as a reasonably smooth idle is found the extra expense to replace the throttle shaft and bush the carburetor body is not justified.
Because of the octane rating of modern gas 85+ it burns slower than the engine is designed to use. That was in the 50 - 60 range which burned much faster. The result is incomplete combustion or carbon formation. That can be reduced or eliminated by increasing the timing to ~ 18 deg. btdc and increasing the gap on the spark plugs from 0.025" to 0.040". The hotter spark at the plugs and timing increase recovers the power that higher octane gas causes.
Your 1930 distributor has a mechanical advance in addition to the spark retard cable. With the mechanical advance working properly there is little reason to even touch the "spark" knob on the dash. It is there to be able to retard the spark if hand cranking the engine. Chevrolets have advanced features compared to Model A Fords.
The hub caps use spring loaded retention tabs. If the springs are weak or tabs worn the caps can be loose on the wheels. Some have used electrical tape or other materials to shim out the space and tighten loose caps.
