This is a 1973 Spider with slightly racy cams, 45DCOE Webers, and Crane ignition.
The original SPICA fuel pump is used, with a fuel pressure regulator set at 3-5psi (there is a fuel P gauge), and a return line back to the tank.
The car is new to me, and I have only driven it on 6 occasions.
Of concern is that 3 times (50% of the time) that I start the car when the engine is cold, it will start right up and sound good. I can even gun the engine and it sounds good.
BUT WHEN I START DRIVING, it is anemic in power, acting and sounding like it is running on 3 cylinders or like the plug wires are incorrectly hooked up, with kicking and some backfiring. Chitty chitty bang bang.
On two occasions while this was happening, there was a 5-8 second run of static and zapping sounds from under the hood, almost like a MIG welder stitching some plates.
I have even let the car sit and warm up a few minutes before driving, and the underpower/backfiring will STILL happen.
The underpower and kicking persists for several miles (maybe 1-3 miles?), then suddenly it "straightens up" and will run perfectly the rest of the time.
BUT, sometimes under identical weather conditions (cooler to cold weather), the car will start right up from cold and run perfectly with none of the kicking and power loss.
Once the car starts running smoothly, there are no further problems. I can stop the car and have left the car for up to an hour, and it will restart and run perfectly well. There is no further loss of power while driving -- until the next morning.
I have checked the plug wires and they are firmly in place on plugs and dizzy cap. I don't see any loose wires coming from the ALT or the coil.
Of possible significance, when starting, I get a lot of water and black carbon-soot onto the ground from the tailpipe, although there is no smoke (like I would expect from an overly rich mixture, stuck choke, etc).
I have checked the oil and the radiator coolant, and there is no evidence of oil or water mixed in the fluids.
I cannot see any type of choke mechanism on the carbs; there is no cable linkage indicating that there might be a manual choke.
I guess there could be water in the gas tank, but I'd think the car would always be running poorly, right?
Any suggestions what might be causing this intermittent problem loss of power when driving the car with a cold engine?
Can something be sticking in one of the carbs that loosens only once the engine is hot?
Can this possibly be an ignition problem? (the zapping sounds under the hood on 2 occasions)
Appreciate any recommendations or specific tests I should do?.
Thanks.
The original SPICA fuel pump is used, with a fuel pressure regulator set at 3-5psi (there is a fuel P gauge), and a return line back to the tank.
The car is new to me, and I have only driven it on 6 occasions.
Of concern is that 3 times (50% of the time) that I start the car when the engine is cold, it will start right up and sound good. I can even gun the engine and it sounds good.
BUT WHEN I START DRIVING, it is anemic in power, acting and sounding like it is running on 3 cylinders or like the plug wires are incorrectly hooked up, with kicking and some backfiring. Chitty chitty bang bang.
On two occasions while this was happening, there was a 5-8 second run of static and zapping sounds from under the hood, almost like a MIG welder stitching some plates.
I have even let the car sit and warm up a few minutes before driving, and the underpower/backfiring will STILL happen.
The underpower and kicking persists for several miles (maybe 1-3 miles?), then suddenly it "straightens up" and will run perfectly the rest of the time.
BUT, sometimes under identical weather conditions (cooler to cold weather), the car will start right up from cold and run perfectly with none of the kicking and power loss.
Once the car starts running smoothly, there are no further problems. I can stop the car and have left the car for up to an hour, and it will restart and run perfectly well. There is no further loss of power while driving -- until the next morning.
I have checked the plug wires and they are firmly in place on plugs and dizzy cap. I don't see any loose wires coming from the ALT or the coil.
Of possible significance, when starting, I get a lot of water and black carbon-soot onto the ground from the tailpipe, although there is no smoke (like I would expect from an overly rich mixture, stuck choke, etc).
I have checked the oil and the radiator coolant, and there is no evidence of oil or water mixed in the fluids.
I cannot see any type of choke mechanism on the carbs; there is no cable linkage indicating that there might be a manual choke.
I guess there could be water in the gas tank, but I'd think the car would always be running poorly, right?
Any suggestions what might be causing this intermittent problem loss of power when driving the car with a cold engine?
Can something be sticking in one of the carbs that loosens only once the engine is hot?
Can this possibly be an ignition problem? (the zapping sounds under the hood on 2 occasions)
Appreciate any recommendations or specific tests I should do?.
Thanks.