Engine 90 GT 5.0 engine pull / rebuild questions

Justin87

Active Member
Aug 7, 2017
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#1
Hello all,

With the weather finally starting to get warm here in Wisconsin, I am going to begin working on my 90 GT. I have a lot of projects planned, one of which is fixing all the oil leaks by pulling the motor.

The oil pan, front/rear main seals, and valve covers are all shot and leak terribly. The questions I have are all related to what else I should be replacing besides just gaskets.

1. The oil pan has two very stripped drain plugs. So I am planning on replacing the oil pan itself. I'm considering getting the Ford Racing High Volume Oil Pump and associated parts but it mentions on the LMR website that the stock pan would need to be "clearanced" and I am not sure what that means or even if it's really nessecary at this point. Does anyone have an experience with this?

LINK: https://lmr.com/item/M6600D2/50L-High-Volume-Ford-Racing-Oil-Pump

2. With the motor out of the car and the oil pan off, what else should I be looking for in terms of excessive wear or damage?

3. Replacing the heads with a set of GT40's off an Explorer. They have already been cleaned up with upgraded springs. Motor is going to be N/A with a few more bolt on's (Explorer intake, cam) I'm assuming at this relatively low power level a basic head gasket set should work, correct? Was thinking something like this:

LINK: https://lmr.com/item/M6051D50/Ford-Racing-Head-Gasket-Bolt-Kit-Mustang-79-95-50

4. Assuming no major problems are found, I am looking for a bottom-end rebuild kit that would use the stock rotating assembly. I have seen a couple different brands on Summit and my local parts stores, just wasn't sure if one was better than the other. I am just trying to freshen things up with new bearings and rings, not trying to build a 331 stroker right now. Any recommendations?

I have been trying to do my research by lurking on previous threads so I apologize if I missed something.

Thanks for all your input.

-Justin
 
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RaggedGT

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#4
I’d vote to go with a stock replacement oil pump. I would keep the stock GT cam or buy a new upgraded cam.
Are you tearing it down to just the block?
 

jrichker

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#5
The high volume oil pump is a Melling pump that has been rebranded.

The oil pan needs to be dimpled with a ball peen hammer to get clearance for the oil pump bolts. Then you can actually install the oil pan on without having it hang on the bolts. With the oil pan off the engine, use a propane torch to heat the pan cherry red where the bolts rub. Then you hammer the inside of the oil pan until it no longer hits on the bolts.

Thanks to Stangnet member bubba-dough for helping to educate all of us by finding this article... :nice:

http://www.mellingengine.com/Portals/5/pdf/pdf_catalog/high-volume-pumps.pdf You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

From the Melling site, for those who didn't follow the link & read the tech note...



High Volume Pumps: Advantages, Myths & Fables

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.


It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.
 
Last edited:

Justin87

Active Member
Aug 7, 2017
40
17
28
31
#6
I’d vote to go with a stock replacement oil pump. I would keep the stock GT cam or buy a new upgraded cam.
Are you tearing it down to just the block?
My plan is currently to pull the motor, pull the whole top end off (I have an explorer upper/lower, and a set of GT40’s), and pull the cam to swap with something (not sure what can yet).

I will be replacing the oil pan, oil pump, oil pickup (possibly with the “high volume” one as mentioned separately) along with the related seals because those things are leaking like a river.

Depending on how things look when I am in there, I would like to do new bearings, piston rings, and clean up the cylinder walls (just because I’m already that far in) but I am not totally sure what I should be looking for other than an OBVIOUS crack or something.
 

John Dirks Jr

5 Year Member
Jun 28, 2013
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#7
X2 on keeping the stock cam if it’s in decent condition. Get a new timing chain. Then get 1.7 full roller rockers. That will nudge the stock cam up a notch and then your entire valve train will be roller.
 

Justin87

Active Member
Aug 7, 2017
40
17
28
31
#8
The high volume oil pump is a Melling pump that has been rebranded.

The oil pan needs to be dimpled with a ball peen hammer to get clearance for the oil pump bolts. Then you can actually install the oil pan on without having it hang on the bolts. With the oil pan off the engine, use a propane torch to heat the pan cherry red where the bolts rub. Then you hammer the inside of the oil pan until it no longer hits on the bolts.

Thanks to Stangnet member bubba-dough for helping to educate all of us by finding this article... :nice:

http://www.mellingengine.com/Portals/5/pdf/pdf_catalog/high-volume-pumps.pdf You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

From the Melling site, for those who didn't follow the link & read the tech note...



High Volume Pumps: Advantages, Myths & Fables

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.


It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.
This was a super detailed and very helpful response. Thank you very much!
 

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