[SusieQ]

I read that the oil pump pickup screen for a Pontiac 400 should be anywhere from 1/2" to a 3/8" from the bottom of the pan. But then I read in another place that it should be closer at 3/8 to a 1/4" from the bottom. So I thought I'd ask the pros on PY Forums! What do you guys recommend?

Susie

[steve25]

There's a cast in locating boss ( small nub ) on the pump body that sets up how far above the bottom of the pan the pick up can go when installed.

[Tom Vaught]

Originally Posted by steve25

There's a cast in locating boss ( small nub ) on the pump body that sets up how far above the bottom of the pan the pick up can go when installed.

Agree with above.

If you had a deep pan depth and a custom oil pick-up would would adjust the screen height to get close to that 3/8" dimension.

I personally like the 3/8" number and will take the 7/16" number as the pick-up is typically not totally flat on Pontiac pumps with factory pick-ups. I try not to be below the 5/16" number and prefer not to be even be there. I avoid having the pick-up at 1/4" from the bottom, if I can.

Others might have different opinions. The notch in the pump is a pretty good locator though.

Tom V.

[TedRamAirII]

I would want somewhat thicker metal for the bracket. But the design is good. Maybe 2 holes, to weld through to the tube. Punch a hole in the strap, then weld through the hole to the tube.

[SusieQ]

Ok guys, here it is.

Sorry for my absence, but I'm a multiple hobby person and I stretch myself thin. Back to the "Goat!"

I'll be aiming for a distance from the bottom of the pan of 3/8" +/- 1/16" and for all the reasons stated during your discussions.

About that bracket that I planned to make? Here it is. I plan to tack weld the bracket around the tube itself and do another tack weld from pickup to bracket so it won't twist. Maybe two tack welds on the tube for extra security?

Anyway...what do you guys think?

[Tom Vaught]

Originally Posted by SusieQ

Ok guys, here it is.

Sorry for my absence, but I'm a multiple hobby person and I stretch myself thin. Back to the "Goat!"

I'll be aiming for a distance from the bottom of the pan of 3/8" +/- 1/16" and for all the reasons stated during your discussions.

About that bracket that I planned to make? Here it is. I plan to tack weld the bracket around the tube itself and do another tack weld from pickup to bracket so it won't twist. Maybe two tack welds on the tube for extra security?

Anyway...what do you guys think?

Some nice fabrication work there. Agree, put a hole in the strap where it lays on the tube and weld it on the inside of the hole to the tube. Same deal for the edges of the strap to the tube. Small bead welds will hold it fine.

Tom V.

[SusieQ]

Originally Posted by Tom Vaught

Some nice fabrication work there. Agree, put a hole in the strap where it lays on the tube and weld it on the inside of the hole to the tube. Same deal for the edges of the strap to the tube. Small bead welds will hold it fine.

Tom V.

Originally Posted by TedRamAirII

I would want somewhat thicker metal for the bracket. But the design is good. Maybe 2 holes, to weld through to the tube. Punch a hole in the strap, then weld through the hole to the tube.

Thank you Tom.

The thickness is 22 gauge. You don't think that would work Ted? What's your opinion on that Tom?

Good idea on the holes to the tube. I was already planning on drilling a hole to fasten the strap to itself where it wraps around the tube, but was going to just have it welded on the edge to the tube itself. Good idea guys! Thank you! But do I understand you right Tom that I should put a weld bead around the perimeter of the strap to the tube? I was just going to put a couple of spot welds on it.

[mrennie]

My experience with a stock pump and replacement oil pan was that with the screen in the notch where it should be, I was getting more like 5/8". This was measured by putting a loose ball of aluminum foil on the pickup then bolting down oil pan to crush it, then take back out and measure. Adding the oil pan gasket would have added another 1/8" of clearance.

I found that trying to get closer by rotating the pickup just tilted it and readings were close on one end and too far on other end.

My point being that if the pan and pickup tolerances are off a bit, you may be limited on adjusting it any closer.

[SusieQ]

Originally Posted by mrennie

My experience with a stock pump and replacement oil pan was that with the screen in the notch where it should be, I was getting more like 5/8". This was measured by putting a loose ball of aluminum foil on the pickup then bolting down oil pan to crush it, then take back out and measure. Adding the oil pan gasket would have added another 1/8" of clearance.

I found that trying to get closer by rotating the pickup just tilted it and readings were close on one end and too far on other end.

My point being that if the pan and pickup tolerances are off a bit, you may be limited on adjusting it any closer.

Initially, I did the same thing with the ball of aluminum foil just to get an idea of how far that notch was from the bottom and came up with the same results...which I'm thinking is way too high is it not?

[grivera]

Originally Posted by SusieQ

Initially, I did the same thing with the ball of aluminum foil just to get an idea of how far that notch was from the bottom and came up with the same results...which I'm thinking is way too high is it not?

What is your measurement?

[SusieQ]

Originally Posted by grivera

What is your measurement?

It was roughly a 1/2"

[Tom Vaught]

I have never been a fan of Aluminum foil as it does not hold its deformed shape exactly after being compressed.

I have some chrome metallic tape used to seal up dryer discharge tubes that send the dryer moisture outside. I tape a couple of pieces of that over the pick-up screen. It
keeps the "Play Dough" from entering the screen.
I put a 1/2" block of flat "dough" inside the pan and the bolt up the pan/gaskets to pan torque specs.

I then remove the pan and then measure the different heights on the dough.
Different way of doing it vs other ways but I know exactly in one operation
where the pick-up screen is vs the bottom of the pan. Kids play dough from
Hobby Lobby is cheap and never wears out.

Tom V.

I remove the chrome metallic tape and the play dough from the pan, lol!

[SusieQ]

Originally Posted by Tom Vaught

I have never been a fan of Aluminum foil as it does not hold its deformed shape exactly after being compressed.

I have some chrome metallic tape used to seal up dryer discharge tubes that send the dryer moisture outside. I tape a couple of pieces of that over the pick-up screen. It
keeps the "Play Dough" from entering the screen.
I put a 1/2" block of flat "dough" inside the pan and the bolt up the pan/gaskets to pan torque specs.

I then remove the pan and then measure the different heights on the dough.
Different way of doing it vs other ways but I know exactly in one operation
where the pick-up screen is vs the bottom of the pan. Kids play dough from
Hobby Lobby is cheap and never wears out.

Tom V.

I remove the chrome metallic tape and the play dough from the pan, lol!

So Tom, you suggest that I adjust it past the notch if the notch is too high correct? (Which it is.)

I'm making a bracket as we discussed a few weeks ago to hold the tube so I'm not concerned about it moving out of place. I bought the metal just yesterday. Just haven't got around to fabricating it yet. I'll share a pic when I'm done and you guys can tell me what you think.

I made a little measuring device to check pan depth and pickup clearance, but Play-Doh sounds like a lot more fun! Thanks for the tip!

[SusieQ]

I did some final measurements. Measurements that I'm sure you'll all find very interesting.

Of course, as the pickup is turned up or down, so does the screen. And small changes on the inboard side result in radical changes at the outside tip of the screen.

The tip of the screen, when the back of the screen touches the top of the gear cover plate (with the engine on the stand upside down,) leaves the tip only 1/8" from the bottom of the pan. And it actually sits inside the little dip where the drain plug goes. So it comes darn near to touching that drain plug bolt. So we're talking really low in the pan. If I sit the back side of the screen in the notch on the underside of the plate, the tip measures 3/4" directly from the tip to the little dip.

After all of this discussion, as I see it, there's only one option, unless of course I alter the cover so the screen can be adjusted with more accuracy, and that's to sit the backside of the screen in the notch which will leave it way high.

Forgive my inability to write this using proper engineering nomenclature and parlance. I hope all of you were able to follow me on this.

Suggestions?

[lust4speed]

The inside area of the 3/4" outside diameter pickup tube is about .33 square inch. The area available under and around the pickup sitting a quarter inch off the pan is about 2.75 square inches which is a very safe amount. Or did I blow it on the math?

[Tom Vaught]

Not by very much, LOL!

Pick-up screen diameter is 3.6 inches.
Area of the pickup if no solid plate across the screen = 10.2 square inches.
So you subtract out the blocker metal bar which is 3.6 inches long by 1.3 inches wide
so that piece blocks 4.68 square inches of the ideal screen area.

So 10.2 square inches minus 4.68 inches = roughly 5.5 square inches of screened pick-up area.

5.5 square inches vs the oil pump screen pipe diameter .600" diameter

Lots of screened area vs the pipe flow area.

Tom V.

[Tom Vaught]

The .600" is the inside diameter which affects the flow rate.

Ideally you would be quite a bit larger on that suction pipe inside diameter dimension for best flow rate with smallest restriction before the pump. Very common on modern small engines to have a 3/4" inside diameter inlet to the pump.
Aston Martin V-12 engines used a inlet pipe closer to 1" inside diameter.
The .600" inside diameter is designed for a low rpm engine.

Tom V.

[chiphead]

That's why I like the Milodon scoop type pickup, it has a very large and short intake pipe between the scoop and the intake of the pump. It does have a 90* turn, so that's not great. There's always a trade off

[Tom Vaught]

One radiused 90 degree turn is not going to hurt you on flow very much.
Charlie66 did a very nice job modifying a 90 degree sharp turn "Box" pick-up into a softer radius
turn for his turbo 4 cylinder engine. It looked great.

This is a 455 SD pick-up with a nice radius turn into the pump but it needed to have a different design entry to make it work well.

Tom V.

[lust4speed]

Getting back to the original question which was how far off the bottom of the pan could the oil pump pickup be placed. The problem might be looked at like computing the area of an air filter, and using this to figure out the capacity under the pickup when 1/4" off the floor. Thinking of this area like the circumference of a cylinder that is the diameter of the pickup and the height being the distance off the floor. We can use Tom's 3.6" screen diameter and this produces a circumference of about 11". Take the 1/4" height from floor to pickup and that gives 2.75 square inches of effective area the oil has available to pass through. This is only about half the capacity of the screen area but many times over the flow rate of the pickup tube area which will be the choke point.

So thinking 1/4" would be totally safe? Distance could be less according to the math, but no reason to push the clearance any tighter.