richen the secondary jet as the barrell cracks open the stock carb goes slightly lean and can cause a buck or jerk

Ok

1. It could be pinging because your vaccuum advance comes on too quickly (get your distributor recurved) or
2. it's running lean on acceleration, the accelerator pump jets need drilling out, or replacing with larger ones..
3. What Teratonga says...

Chris

The jerking is probably just the 2nd barrel opening if you have the standard carb - mine does the same and if I hold it right at the point of opening it plays up. Mash it past there and away she goes. Pinging either indicates low octane gas or timing that is too far advanced. If you have checked your timing and it's at 7 degrees then look at the inside of the dizzy. Make sure the vacuum advance is hooked up and working.

Ive got a little A-14 that i have checked the timing co's stuff like that.My problem is that if im at half acceleration its jerking slightly as if there is something blocking the jets but im not sure,but on full accelaration she goes like a bat out of hell any suggestions? there is a slight ping aswell come to think of it.Help please its driving me nuts!!