I have a 351 putting a new pan on with pick-up,but the pick-up sits on the main girdle so I have to bend it up.
Can someone tell me how far the pick-up is supposed to sit off of the oil pan bottom?
Sounds as if you may just have the wrong pickup tube and/or style of pump for that oil pan. I know that the 260/289/302/5.0L series had several different OEM pans, pumps, and pickups available, and lots of aftermarket ones, but I'm not up on the 351's. If at all possible, try to get a pump/pickup/pan combination that will work without modification, as there is a lot more to it than just bending a piece of pipe. (see below)
Try to measure a stock oil pumps' pickup depth to that engines' pan. That is the safest guide. If you can get a better fitting pump/pickup/pan combination, shoot for not closer than about 1/4" from the bottom of the pan as a general rule. A slight bit more may be better, but not much more, or the pump will be more prone to cavitate at higher rpm, heavy braking or acceleration, or in higher "g" turning.
Also, that way even if you get a slight bend or dent in the bottom of the pan, (from running over something like a 2"x4" in the road for example) the pickup will still function reasonably well. If it's parallel to a flat part of the pan and marginally too close to the bottom to begin with, any slight damage to the bottom of the pan in that area and it's suction (and your engines' oil pressure) may well be compromised.
In any case, when you get the pieces in hand, put a small piece of thin plywood or rigid styrofoam in the section of the pan where the pickup extends pan and see if the pan goes up all the way. With the styrofoam, it will probably make a dent that you can measure by cutting straight through. If the pan doesn't go up all the way, and the pickup is hitting the pan without any spacer in the pan, measure how much you'll have to bend it to get decent clearance.
If you think that you'll have to bend it more than a half an inch or so, it will be a very lucky day for you if you don't kink it somewhere to the point that the flow is adversely affected, and the pickup will probably end up being at much the wrong angle to boot, so in that case, get someone to cut and weld or braze it for you. If it only has to bend maybe a quarter of an inch or so, you may be able to do it without hassling with major tools and causing serious damage.
If you don't have a proper tubing bender, you'll probably have to heat the tube to soften it in order to bend it in the direction that you want it to move, and it may still distort enough to cause restriction. Bend it a little at a time and apply heat to it CAREFULLY, or you'll be liable to break or melt one of the brazed connections or kink the tube.
In any case, if you start bending the tube, getting it to end up level in relation to the oil in the pan still isn't guaranteed, and if it angles up too much, either front to back or sideways to the static level of the oil in the pan, it will cause pump cavitation and oil starvation much more easily, so it's important that it be at the same angle that the original condition oil pump pickup was before bending it.
The pick-up is the right one for the pan,the problem I am having is the pick-up has to bolt up next to the main support instead of the main cap,so it is lowering the pick-up lower into the pan.