Electrical Gauges Help

[Drake]

I have a 1985 Blazer that I just put a V8 carb with a 7004R. Everything works fine except for the dash gauges I used all the sending unit from the 2.8. Sometime the gauge will peg out and or go half way or back to zero When I step on the brakes the gauge moves but do not read correctly. I have the ground strap to the block. Please HELP!

[IceQueen]

sounds like a bad ground check your grounds in the cab aswell as in the wire harness going to the engine bay your probably missed one.