[TX_BEAST]

I need to know approx. what reading i should get off compresssion guage for the motor in my bronco. it si the 351m still has stock heads and pistons but i didnt run test on it after rebuild so i dont know what to it should be.
thanks justin

 

[BigWheelz]

Not much, I would estimate 120-150 psi. Pressure is not really what you should be concerned with on a compression test anyways. What you want to see is that all cylinders are reading within the same pressure +/- 10% and that each cylinder bumps up to 90% of its maximum pressure with a few strokes. If there is a signifigant difference between cylinders and/or some cylinders are slow to build compression, then you have a problem.