Qft carburetor help
OK.
Try to accelerate as gentle as possible and see if it still happens.
If its does, then the beginning of transisition is too lean. Could be as simple as a slight adjustment of the throttle position at idle and a slight change in initial timing.
If it does not happen on gentle acceleration from stop, then an accelerator pump cam change is probably the answer.
So that gets us back to the chart.
If the throttle is halfway opened, that's about 45*; and if its fully open, thats close to 90* or straight up and down.
The throttle blade doesn't start at exactly horizontal, so the zero on the graph is the idle position, not true horizontal.
To accelerate from a stop on a local street, the throttle isn't going to be opened very much. Lets say its 10 degrees.
Look at the bottom of the graph, go to 10.
Then take your finger and go up from the 10 degree mark to the pink line.
Look all the way to the left. That's on the first line.
Now keep going up from the 10 degree mark and we see most of the other cams are around the second line.
What this means is in the first 10 degrees of the throttle opening, the pink cam lifts the pump lever 1/2 as much as the others. So the pink cam causes the least amount of diaphram movement and so pushes the least amount of fuel out of the nozzles at the smallest throttle opening.
Screenshot from the 2012 Catalog.
You can see the shape of the pink cam is very gentle at the begining compared to the green and blue cams - both have a very abrupt initial lift.
Then you're talking about street driving.
OK.
Try to accelerate as gentle as possible and see if it still happens.
If its does, then the beginning of transisition is too lean. Could be as simple as a slight adjustment of the throttle position at idle and a slight change in initial timing.
If it does not happen on gentle acceleration from stop, then an accelerator pump cam change is probably the answer.
So that gets us back to the chart.
If the throttle is halfway opened, that's about 45*; and if its fully open, thats close to 90* or straight up and down.
The throttle blade doesn't start at exactly horizontal, so the zero on the graph is the idle position, not true horizontal.
To accelerate from a stop on a local street, the throttle isn't going to be opened very much. Lets say its 10 degrees.
Look at the bottom of the graph, go to 10.
Then take your finger and go up from the 10 degree mark to the pink line.
Look all the way to the left. That's on the first line.
Now keep going up from the 10 degree mark and we see most of the other cams are around the second line.
What this means is in the first 10 degrees of the throttle opening, the pink cam lifts the pump lever 1/2 as much as the others. So the pink cam causes the least amount of diaphram movement and so pushes the least amount of fuel out of the nozzles at the smallest throttle opening.
Screenshot from the 2012 Catalog.
You can see the shape of the pink cam is very gentle at the begining compared to the green and blue cams - both have a very abrupt initial lift.
