Tweet
After I got a good accelerator pump shot going in my squaretop, I ran into ANOTHER bog problem, plus having to run with the choke halfway out to get any sort of light acceleration.
This did absolute wonders for fuel mileage- down to 4-5 mpg, even though the plugs looked slightly lean. I started looking for a big air leak or blocked fuel passages, but found none.
What I did find was the Accel Pump's Evil Twin- Skippy, the Stepup Jet. This circuit "steps in" where the accel pump leaves off, and provides light-duty accel requirements. Pic #1 shows what it looks like in the E7F1 & E7S1 carb- it's in the same location in the Roundtop carb, but is smaller in size. The spring-loaded rod is held down by a tiny vacuum piston until acceleration weakens engine vacuum and allows the needle to rise out of the jet.
Pic #2 shows the Squaretop jet on right, and an E7T2 jet at left. My problem was that my jet had never been drilled out! Pic #3 shows the normal E7T2 jet on the right and my solid metal E7F/S1 jet on the left The correct hole size is .0492" (1.25 MM), but I tried .046", as it was the closest number drill size I had on hand.
This made a considerable difference- just a very slight hesitation, and no auxilary choke requirements. I may try playing with float levels a bit before drilling out the jet any larger. Stay tuned...
This did absolute wonders for fuel mileage- down to 4-5 mpg, even though the plugs looked slightly lean. I started looking for a big air leak or blocked fuel passages, but found none.
What I did find was the Accel Pump's Evil Twin- Skippy, the Stepup Jet. This circuit "steps in" where the accel pump leaves off, and provides light-duty accel requirements. Pic #1 shows what it looks like in the E7F1 & E7S1 carb- it's in the same location in the Roundtop carb, but is smaller in size. The spring-loaded rod is held down by a tiny vacuum piston until acceleration weakens engine vacuum and allows the needle to rise out of the jet.
Pic #2 shows the Squaretop jet on right, and an E7T2 jet at left. My problem was that my jet had never been drilled out! Pic #3 shows the normal E7T2 jet on the right and my solid metal E7F/S1 jet on the left The correct hole size is .0492" (1.25 MM), but I tried .046", as it was the closest number drill size I had on hand.
This made a considerable difference- just a very slight hesitation, and no auxilary choke requirements. I may try playing with float levels a bit before drilling out the jet any larger. Stay tuned...
Comment