Last fall, I picked up a 1964 Chevy II 300 with 194ci-6cyl and 3 speed manual column shift. I've been driving this ol' beauty as a sunny weather daily driver. (Here in NC, that's most days.) When I first got it, it ran pretty rough and was only getting about 14 MPG. Since then, I replaced pretty much all of the normal tune-up / maintenance parts:
Also, a previous owner had replaced the fuel pump quite recently.
I've been running high octane gas, and I've been including lead substitute in every other fill-up. The car has improved from 14 MPG to 20 MPG (highway+city driving), so the tune-up work definitely seems to have helped.
I initially adjusted everything to factory specs, including the valves, dwell, timing (8 deg BTDC), plug gap, idle mixture, idle RPM (500), choke/high idle, etc. At these specs, the car tends to stall at idle -- especially when the engine's cold. I've had to turn the idle speed up a bit to help. It seems to be fine at about 570 RPM low idle.
The problem is, there is almost always a slight hesitation when accelerating in first gear. This is especially annoying when I'm stopped going up a hill. I have to feather the clutch a lot to keep from stalling. Once the car is moving, the "power curve" kicks in, and it's fine. There is plenty of power, and I don't have any hesitation at all once the car is moving. It's only an issue starting out from idle.
The timing seems to advance as it should. Vacuum levels seem about right, and there don't seem to be any vacuum leaks anywhere. When I disconnect the vacuum advance and accelerate, the dwell angle remains pretty constant -- only varying about one degree. So I figure the distributor is still in good shape.
I'm inclined to believe the problem is with the acceleration pump, since that seems like an obvious culprit -- even though I've replaced the spring and plunger. My brother told me that he remembered hearing something years ago that this is a common problem with this type of carburetor, and that there is a special kit (heavier spring?) to jazz up the accelerator pump a bit.
I was wondering if any of you all might have some ideas about this. I'm not looking to burn rubber necessarily, but I do want it to perform a little better out of first. If this problem is common for the Rochester B4C, I'd be willing to try modifications or a different carburetor if need be.
I'm otherwise very happy with this vehicle. It's a pleasure to drive -- especially on the open road.
- spark plugs and wires, cap, rotor, condenser
- PCV valve
- fuel filter
- air filter
- battery wires, ground straps
- carburetor rebuild (Rochester B4C 1 bbl)
- heater hoses
- thermostat
- fan belt
Also, a previous owner had replaced the fuel pump quite recently.
I've been running high octane gas, and I've been including lead substitute in every other fill-up. The car has improved from 14 MPG to 20 MPG (highway+city driving), so the tune-up work definitely seems to have helped.
I initially adjusted everything to factory specs, including the valves, dwell, timing (8 deg BTDC), plug gap, idle mixture, idle RPM (500), choke/high idle, etc. At these specs, the car tends to stall at idle -- especially when the engine's cold. I've had to turn the idle speed up a bit to help. It seems to be fine at about 570 RPM low idle.
The problem is, there is almost always a slight hesitation when accelerating in first gear. This is especially annoying when I'm stopped going up a hill. I have to feather the clutch a lot to keep from stalling. Once the car is moving, the "power curve" kicks in, and it's fine. There is plenty of power, and I don't have any hesitation at all once the car is moving. It's only an issue starting out from idle.
The timing seems to advance as it should. Vacuum levels seem about right, and there don't seem to be any vacuum leaks anywhere. When I disconnect the vacuum advance and accelerate, the dwell angle remains pretty constant -- only varying about one degree. So I figure the distributor is still in good shape.
I'm inclined to believe the problem is with the acceleration pump, since that seems like an obvious culprit -- even though I've replaced the spring and plunger. My brother told me that he remembered hearing something years ago that this is a common problem with this type of carburetor, and that there is a special kit (heavier spring?) to jazz up the accelerator pump a bit.
I was wondering if any of you all might have some ideas about this. I'm not looking to burn rubber necessarily, but I do want it to perform a little better out of first. If this problem is common for the Rochester B4C, I'd be willing to try modifications or a different carburetor if need be.
I'm otherwise very happy with this vehicle. It's a pleasure to drive -- especially on the open road.