I hope some body can help me determine if I need to shave my intake on my 351c. I have it together and it acts like it has a typical vacuum leak, but I'm unable to find any. When I installed this it seems the front and back ends of the manifold appeared to be a little higher off the block. I have afd 2v heads with an air gap manifold. The holes line up to were they bolt to the heads, but they are not exact center, end up a little low in the intake bolt bore, any ideas or suggestions would be great thanks. The engine seems to shake a little more than it should also.