4 link adjustment

took my 70 dart tube chassis four link car out to a test n tune for the 1st time yesterday. 1st pass just drove down and car drives nice and straight. 2nd pass left off the brake at 4000 and car comes up and wants to go left, let off easy. 3rd pass put more air in the left tire, left on the brake 4000 comes way up wants to go right, let off hit it hard at the 1/8 mark and went 10.48 @ 139mph. i know I can get it to go straight, any info on how to get the front to stay down? Would I be going in the right direction by lowering the front bars? It's my 1st big tire chassis car any help would be great.