New Guy, checking the place out Options

[Sk8erBri]

I bought a 1975 914 2.0 and just found out about this sight. I am having a problem with getting my timing set properly. i change the points cap and router and now i am having nothing but problems getting it timed. i only have a TDC mark on the fan. I measured out where 27 deg BTDC would be and tryed to set to it, but here is what is happening.

it starts and runs fine, i can take off from stop at a normal speet and it sounds good, but if i really try to get on it (like we all know that is how it wants to be treated), it starts to knock and sounds like the engins is about to crack.

i have tryed to time it all different ways, before 27 deg after 27 deg, i have not played with the vaccume system yet, but all was running fine before i changed stuff around, so i dont thing i would have a problem with the vaccume system since i did not change any thing there. Any ides????