Most of the time when an almost stock VW is pinging its running too lean or the timing is too far advanced. Check your spark plugs they should be a nice light brown color on the porcelain, if they are white or have small black specks it's too lean and detonating.
I purchased a 65 with an 1835 and kadrons, about half way home from Clear Lake on my way to Danville CA (3 1/2 hour trip one way) I could smell the hot engine and pulled over, it was baking! A VW shop in Clear Lake had just tuned it and changed the jets for "better fuel milage" after reading the plugs on the side of the road I knew I was in trouble. I drove very slowly the rest of the way home, after tuning the carbs I found they were 4 jet sizes too small! This made the car way faster as a side benefit.
That same car I later found had the shift rod bailing wired up near the shifter to help with a worn shift rod bushing hidden under the carpet!
Good luck with your cool car!
VR
