Hey guys,
Over the winter I had the carburetor rebuilt on my 70 Newport for purely preventive measures. The car ran/drove perfect prior to the rebuild so I feel confident this issue I am about to describe is carburetor related.
On to my issue....
I finally got to take the car out now that the weather is warming up but I have a bogging issue during the first 20 or so minutes of using the car. It happens upon take off from a stop or under light throttle. Under very light throttle ( 5-10 mph) you can feel the car pulsating. Under light acceleration from a stop the engine will bog down and almost stall but then the engine catches and is fine at heavier acceleration. Acceleration at full throttle is always perfect. It seems like the issue is happening at off idle/partial throttle under any load because if in neutral the engine revs up and idles great. Anyways, after the 20 minute or so time frame things get better and feel normal at all throttle positions while driving.
Stock air cleaner set up is still in place with the preheat pipe working. I have a decent understanding of how to tune carburetors. I have the carb set to run at a steady vacuum around 16-17 . Idle is nice and smooth always. Choke works. Fast idle set etc.
For curiosity sake I have set the idle mixture screws in various positions rich and lean and cannot get this bog to go away. The only thing I can think of is possible the accelerator pump may need to be adjusted? You can see the fuel squirt in the carb so I know it is working but maybe not well enough when cold. I would like to get advice before taking the carb off and bringing it back to the re-builder who is very reputable and I have never had an issue working with before. Usually his carbs are dialed in very nicely right out of the box.
Any help would be appreciated.
Over the winter I had the carburetor rebuilt on my 70 Newport for purely preventive measures. The car ran/drove perfect prior to the rebuild so I feel confident this issue I am about to describe is carburetor related.
On to my issue....
I finally got to take the car out now that the weather is warming up but I have a bogging issue during the first 20 or so minutes of using the car. It happens upon take off from a stop or under light throttle. Under very light throttle ( 5-10 mph) you can feel the car pulsating. Under light acceleration from a stop the engine will bog down and almost stall but then the engine catches and is fine at heavier acceleration. Acceleration at full throttle is always perfect. It seems like the issue is happening at off idle/partial throttle under any load because if in neutral the engine revs up and idles great. Anyways, after the 20 minute or so time frame things get better and feel normal at all throttle positions while driving.
Stock air cleaner set up is still in place with the preheat pipe working. I have a decent understanding of how to tune carburetors. I have the carb set to run at a steady vacuum around 16-17 . Idle is nice and smooth always. Choke works. Fast idle set etc.
For curiosity sake I have set the idle mixture screws in various positions rich and lean and cannot get this bog to go away. The only thing I can think of is possible the accelerator pump may need to be adjusted? You can see the fuel squirt in the carb so I know it is working but maybe not well enough when cold. I would like to get advice before taking the carb off and bringing it back to the re-builder who is very reputable and I have never had an issue working with before. Usually his carbs are dialed in very nicely right out of the box.
Any help would be appreciated.
