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drilled oil gallery

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513178 by Roy Didn't someone claim to solve this problem by feeding the center main cap from the oil pump ? CRS

That's certainly a direct approach.
But that would be unfiltered oil, OK for a racecar ... for a street car, maybe not so much.

Plus the oil pump delivers a fixed volume per RPM.
Any too much extra oil sent to the center main, is less available to all the rest.
So now maybe #1 or #4 rod bearing will fail more often instead of #3.

The goal is to distribute the oil uniformly, so that none of them fail more often than the others.

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colodad Avatar
colodad Silver Member Calvin Williams
Grand Junction, CO, USA   USA
1979 Triumph Spitfire 1500 "Spitty"
In reply to # 1513167 by clshore I concur with the pressure results you observed through the bushing, I've observed similar drops but less precision.
But I disagree with your conclusion that the size or surface roughness of the 'waist' is the cause of the pressure delta.
But the experiment you propose should help to uncover what is actually happening, by supporting/disproving your conclusion.

I'd like to instrument a Spitfire oiling system.

Copper capillary tubing is easy to obtain, 0.026" ID x 0.072 OD is the smallest common size, a 16 ft roll is $17 on Amazon.
Fittings or bolt seals used on the oiling system can have a #49 hole drilled into the center, so that a length of capillary tubing can be soldered in place.
The inner length can be 'snaked' into the passages, cut to length to place the open (sensing) end deep inside the motor.
This enables actual running pressure readings in areas of interest, perhaps even right where the passage delivers oil to the main bearings.
The outer length can be soldered to a connection fitting, for attachment to gages or to pressure measurement sensors.

Could hook up a 4 channel Data Acquisition like this one for $59

https://www.dataq.com/products/di-1100/

Using 4 pressure sensors like these:

https://www.mouser.com/ProductDetail/Honeywell/ABPMLNV150PGAA3?qs=sGAEpiMZZMvhQj7WZhFIAIc6zRP3uSZW4YfvQBxlQvwGGBtuQHUmKw%3d%3d

And capture the datastream on your PC, for review and analysis.

Hmm, am I obsessing again?

Hmm, making it rocket science...

The taps are already in the oil passage, just pull the plugs & connect the tubing for the gauges.

Or run a line from the front tap to the rear tap, it should equalize the pressure difference.


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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513195 by colodad
In reply to # 1513167 by clshore I concur with the pressure results you observed through the bushing, I've observed similar drops but less precision.
But I disagree with your conclusion that the size or surface roughness of the 'waist' is the cause of the pressure delta.
But the experiment you propose should help to uncover what is actually happening, by supporting/disproving your conclusion.

I'd like to instrument a Spitfire oiling system.

Copper capillary tubing is easy to obtain, 0.026" ID x 0.072 OD is the smallest common size, a 16 ft roll is $17 on Amazon.
Fittings or bolt seals used on the oiling system can have a #49 hole drilled into the center, so that a length of capillary tubing can be soldered in place.
The inner length can be 'snaked' into the passages, cut to length to place the open (sensing) end deep inside the motor.
This enables actual running pressure readings in areas of interest, perhaps even right where the passage delivers oil to the main bearings.
The outer length can be soldered to a connection fitting, for attachment to gages or to pressure measurement sensors.

Could hook up a 4 channel Data Acquisition like this one for $59

https://www.dataq.com/products/di-1100/

Using 4 pressure sensors like these:

https://www.mouser.com/ProductDetail/Honeywell/ABPMLNV150PGAA3?qs=sGAEpiMZZMvhQj7WZhFIAIc6zRP3uSZW4YfvQBxlQvwGGBtuQHUmKw%3d%3d

And capture the datastream on your PC, for review and analysis.

Hmm, am I obsessing again?

Hmm, making it rocket science...

The taps are already in the oil passage, just pull the plugs & connect the tubing for the gauges.

Or run a line from the front tap to the rear tap, it should equalize the pressure difference.

I think you are missing the whole point of the capillary tubing.
The challenge with any measurement is to avoid errors introduced by the instrumentation itself.
We seek to assess pressure losses in the oil passages, by measuring pressure at various points along the flow path.
Many of the passages are deep inside the motor, so snaking a sensing tube from the external ports inside gives us access to those points.
Since the passages are relatively small, using large diameter tubing would partially block the flow, and introduce errors.
Capillary tubing allows remote sensing of pressure, as there is no material flow, it need only transmit pressure, so the minimum diameter can be used.
Our cars use 5/16x24 hex screws with copper washers to seal the passages, with a 1/4" or 3/8" NPT fitting in the middle port.
The reason that I suggest those plugs be drilled and soldered is cost and convenience.
Standard threaded fittings in those sizes for capillary tubing is specialized hardware, either unobtainable or expensive.

As for rocket science, the basic technology was worked out for steam engines and industrial machinery in the 1800's.
Data Acquisition is more recent, and you can blame NASA and the Space Race for all this electronic and computer stuff, although military needs were the real drivers.
The equipment I've suggested is cheap and capable of capturing and searching and reviewing hours of data in precise detail, with 4 channels, 250 snapshots per second,
and signal bandwidth that reveals every pulse, spike, sag, ripple, and nuance, requiring no tending, no adjustment, no fiddling.
It can even do so while I drive the car in real world usage under all conditions.
Can you say the same for watching the needles on multiple mechanical gages, perhaps recording your observations on a pad, hoping you didn't miss something
while you were writing or flipping the pages?

But there's no technology I've suggested using that does not exist in abundance under the hoods of every single new car on the planet.

Electronic pressure sensors? Check
Digital sensor data capture and storage? Check
Playback and analysis of events? Check

The whole reason we are even engaged in any of this is because of bearing failures that we suspect are due to issues with either oil flow, oil pressure, or both.
We can easily measure the pressures at the ports, but not so with the internal parts of the system.
Don't you think that measuring and knowing what the oil pressures are at the entry to the bearings themselves is useful in understanding the problems?
Don't you think that measuring and knowing the actual pressure drops existing within the oil distribution system is useful in understanding the problems?

The method I've proposed allows exactly that.

Until we can measure it, we are basically just guessing.

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colodad Avatar
colodad Silver Member Calvin Williams
Grand Junction, CO, USA   USA
1979 Triumph Spitfire 1500 "Spitty"
well science ya put it that way.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
You can mesure the oil pressure to the point that it enters the crank shaft. What about the rod bearings?

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
One of the things I've been thinking about is increasing the bore of the main oil gallery - the bore as standard is 7/16" (11.1mm). I'm not sure how much it could be safely bored out, and it would need larger threaded end plugs, but it might just help to reduce the oil pressure drop along its length.

The other thing I noticed was all Spitfires up to around 1975 (including the US Spit 1500 from 1973) had the same oil pump (217058), with a 1" long rotor. At some point around that time, a different oil pump (TKC1974) was fitted for all future engines, which although the same diameter, has a rotor length of 1.25". I'm assuming this was an attempt to improve the oil delivery, possibly based on problems experienced with the 1500 engine. Interestingly, the 6 cylinder GT6 engine has a similar pump, but the rotor is 1.5" long. Unfortunately, it's not a straight swap, as the drive shaft for the Spitfire pump has a slot at its upper end, whilst the GT6 has a peg, meaning that the drive shaft in the driving gear is also different. (This in itself might be relatively easy to solve, by swapping over the driving gear shafts, or remachining slots/pegs as appropriate.) There is also a difference in the orientation of the ports on the upper surface of the oil pump body, meaning that the GT6 pump will not match to the oil holes in the Spitfire block. I was wondering - has anyone on here attempted (or succeeded) in fitting parts from a GT6 oil pump into a Spitfire to improve oil delivery?

jmac Avatar
jmac Silver Member Jere McSparran
Greenup, IL, USA   USA
1978 MG Midget "Therapy"
1978 MG Midget "(SOLD)"
This is a very interesting topic. I spend 99% of my time over on the Midget forum as I am a Midget owner but of course using the same 1500 engine.
I have been studying and rebuilding 1500s for others. Per John Twist and some of his videos I have been drilling out the center main to 5/16" without any real data on how much oil pressure loss occurs on the rear of the engine and the rocker train.
I have not noticed much, if any, pressure loss after drilling out the center main. I have been attributing that to the fact that the passages from the main to each of the rod bearings in the crankshaft are still the same. IMHO, by opening up the center main passage I am simply insuring that the rod bearings are getting sufficient oil since the passage supplies 2 bearings.
I think, without any real data to share, that perhaps the oil pressure sensor should be moved from the base of the distributor to the next gallery plug rear (it would need to be drilled and tapped). If the oil pressure is similar at that point the change in the passage size will have no damaging affect on the remainder of the engine.

Please correct my "stinkin thinkin".



JMac
JMacEngineShop.Weebly.com

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
Jere, I feel the same way. I have not observed a difference in overall oil pressure, no matter how much boring of passages or aux oil feeds are added to the main gallery.

I suspect the oiling issue is after the oil reaches the crank shaft, OR is the result of a harmonic interuption
of flow due to the metered feed to the valve gear.

Also, more work could be done to adress optimal bearing clearances/ surface finish to allow lower viscosity oil to be used.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513285 by grumpicus One of the things I've been thinking about is increasing the bore of the main oil gallery - the bore as standard is 7/16" (11.1mm). I'm not sure how much it could be safely bored out, and it would need larger threaded end plugs, but it might just help to reduce the oil pressure drop along its length.

The other thing I noticed was all Spitfires up to around 1975 (including the US Spit 1500 from 1973) had the same oil pump (217058), with a 1" long rotor. At some point around that time, a different oil pump (TKC1974) was fitted for all future engines, which although the same diameter, has a rotor length of 1.25". I'm assuming this was an attempt to improve the oil delivery, possibly based on problems experienced with the 1500 engine. Interestingly, the 6 cylinder GT6 engine has a similar pump, but the rotor is 1.5" long. Unfortunately, it's not a straight swap, as the drive shaft for the Spitfire pump has a slot at its upper end, whilst the GT6 has a peg, meaning that the drive shaft in the driving gear is also different. (This in itself might be relatively easy to solve, by swapping over the driving gear shafts, or remachining slots/pegs as appropriate.) There is also a difference in the orientation of the ports on the upper surface of the oil pump body, meaning that the GT6 pump will not match to the oil holes in the Spitfire block. I was wondering - has anyone on here attempted (or succeeded) in fitting parts from a GT6 oil pump into a Spitfire to improve oil delivery?

I'll be opening up the main gallery for my Turbo build.
I have a 1/2" x 16" long drill, and also a 9/16" x 16" drill, with the center bushing removed you can unscrew the plugs and drill through from each end.
The threaded plugs at the ends have to be enlarged, and at the front there is an issue, because the intersecting passage is so close to the front surface that a standard plug will block it.
The Spitfire front plate actually has a clearance hole that allows the plug to stick up proud from the surface, to give internal oil passage clearance.
Might have to turn down the head of the larger front plug to give enough room.
I'll try 1/2" first, and if that goes well and there's enough wall material, maybe go to 9/16".

My calculations show that the 7/16" gallery has about 7.4 psi drop at full flow, the 1/2" mod reduces that 41% to 4.3 psi, and the 9/16" mod reduces it 63% to 2.7 psi.
For comparison, the center oil feed shows about 20.8 psi drop at full flow, the 5/16" mod reduces that 59% to 8.5 psi, and the 11/32" mod reduces it 72% to 5.8 psi.

Here's another Crazy Idea, for dry sumping a Spitfire:
Remove the lower oil pickup tube and plate.
Fit a GT6 pump body at the bottom with an adaptor plate in between.
The adaptor plate has a threaded port to the Spitfire oil pump inlet, and another threaded port to the GT6 oil pump outlet.
Separate the shaft from the Spitfire pump, and machine a drive slot to fit the GT6 drive tang.
Separate the shaft from the GT6 pump, shorten it, and machine a new drive tang to match the new drive slot above.
On the bottom end of the GT6 pump, fit a plate and short pickup tube.
Reassemble the stack.
Remove any baffles or obstructions in the pan, fit the pump assembly.
Fit an oil scavenge line and an oil pressure line to the ports on the center adaptor plate, routed through the pan or block wall to an external dry sump oil tank.
With a 1-1/4" spitfire rotor and a 1-1/2" GT6 rotor, the pumping ratio is only 1.2, a bit marginal, so a large capacity tank is recommended.
But if a 1" Spitfire rotor is used, the ratio is 1.5, much better, so a smaller tank could be employed.

Why bother, if there is only a single scavenge stage?
1) Eliminates any possibility of ever ingesting air.
2) Allows for far greater oil system capacity.
3) BLING Baby! (My car is Dry Sumped, wanna see my oil tank, it holds 10 quarts)

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
In reply to # 1513339 by clshore
My calculations show that the 7/16" gallery has about 7.4 psi drop at full flow, the 1/2" mod reduces that 41% to 4.3 psi, and the 9/16" mod reduces it 63% to 2.7 psi.
For comparison, the center oil feed shows about 20.8 psi drop at full flow, the 5/16" mod reduces that 59% to 8.5 psi, and the 11/32" mod reduces it 72% to 5.8 psi.

What working viscosity did you use for those estimates?

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513344 by Tonyfixit
In reply to # 1513339 by clshore
My calculations show that the 7/16" gallery has about 7.4 psi drop at full flow, the 1/2" mod reduces that 41% to 4.3 psi, and the 9/16" mod reduces it 63% to 2.7 psi.
For comparison, the center oil feed shows about 20.8 psi drop at full flow, the 5/16" mod reduces that 59% to 8.5 psi, and the 11/32" mod reduces it 72% to 5.8 psi.

What working viscosity did you use for those estimates?

Assumes 6000 RPM, pump swept volume 0.577 cu/in
3 main @ 1 GPM, 4 rod @ .90 GPM, 4 cam @ .225 GPM
30W motor oil @ 100C, density=0.9, viscosity=200

The purpose was to help assess the relative impact of changing passage ID, rather than absolute accuracy of the numbers.
I figure the numbers could be +- 50% either way.

It's one reason I'm interested in instrumenting the oiling system, as mentioned above, to get some real numbers in situ.

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
In reply to # 1513339 by clshore
My calculations show that the 7/16" gallery has about 7.4 psi drop at full flow, the 1/2" mod reduces that 41% to 4.3 psi, and the 9/16" mod reduces it 63% to 2.7 psi.
For comparison, the center oil feed shows about 20.8 psi drop at full flow, the 5/16" mod reduces that 59% to 8.5 psi, and the 11/32" mod reduces it 72% to 5.8 psi.

Carter - is it possible to drill the centre oil feed to 11/32" (8.73mm) all the way through? I've actually drilled mine to 8mm (a shade over 5/16" ) but the drill was getting close to the internal thread for the oil pressure switch.

I like the idea of stacking the oil pumps to provide the scavenge pump for the dry sump, but is there any chance that running two pumps from the single peg & slot drive underneath the drive gear might overload or break the coupling? I seem to remember that BL had a problem with the oil pump drive in their 1960s Mini, and changed over to a 'spider drive' coupling when they introduced a higher capacity pump for their 1300 engines.



Edited 1 time(s). Last edit at 2018-02-15 04:38 AM by grumpicus.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513394 by grumpicus
In reply to # 1513339 by clshore
My calculations show that the 7/16" gallery has about 7.4 psi drop at full flow, the 1/2" mod reduces that 41% to 4.3 psi, and the 9/16" mod reduces it 63% to 2.7 psi.
For comparison, the center oil feed shows about 20.8 psi drop at full flow, the 5/16" mod reduces that 59% to 8.5 psi, and the 11/32" mod reduces it 72% to 5.8 psi.

Carter - is it possible to drill the centre oil feed to 11/32" (8.73mm) all the way through? I've actually drilled mine to 8mm (a shade over 5/16"winking smiley, but the drill was getting close to the internal thread for the oil pressure switch.

I like the idea of stacking the oil pumps to provide the scavenge pump for the dry sump, but is there any chance that running two pumps from the single peg & slot drive underneath the drive gear might overload or break the coupling? I seem to remember that BL had a problem with the oil pump drive in their 1960s Mini, and changed over to a 'spider drive' coupling when they introduced a higher capacity pump for their 1300 engines.

Easy enough to drill & tap the oil pressure port to the next NPT size, and use an adaptor sleeve or fitting for the switch.
The hole in the main bearing shell can be enlarged to help blend to the larger passage, make it oval to avoid decreasing the load bearing surface of the bearing.
Or, as others have suggested, machine an auxiliary groove into the bearing housing to distribute oil around behind the bearing to the hole in the upper bearing shell.
This augments the flow provided by the normal bearing center groove.
With big journal cranks, you must offset the auxiliary groove fore or aft because the studs/bolts are so close to the bearing housing surface.
Can use a hand grinder to create short connector passages from the bearing holes to the auxiliary groove.

As for the oil pump drive, I think it's held up well on the 6 cylinder cars, where the torque load is about 50% greater than the Spitfire.
As a scavenge pump, the larger pump will see a significantly smaller pressure head, as it's only delivering the oil through the oil line to the oil tank,
not pressurizing the oil system to squeeze oil past the bearing clearances.
So the torque required to spin that scavenge pump will also be proportionally smaller.
Similar gerotor pump stacks employed by dry sump systems often employ a solid shaft having pockets for woodruff keys, so that pressure and scavenge can be driven on same shaft.

https://www.pegasusautoracing.com/group.asp?GroupID=FF16OPPARTTIT

The inner gerotors have slots machined in rather than pins, allowing the 'stacks' of pump parts to be assembled/disassembled by sliding them along the shaft to engage.
The Spitfire/TR6/GT6 drive gears use a separate short drive shaft and gear with a cross pin, so a single long pump shaft could be fabricated and attached to the stock gear.
But I think modifying the stock shafts will work just fine, and certainly be a ton less expensive than a custom built shaft.

I have not measured, but it's possible that a Spitfire drysump stack with two smaller 1" scavenge stages instead of a single large one could be fabricated.
It would require two spacer plates with fittings, so space may be too tight.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513272 by Tonyfixit You can mesure the oil pressure to the point that it enters the crank shaft. What about the rod bearings?

Yes, it's quite a challenge.
Temperature, G-loading, vibration, wireless connections ... cost.
There are several wireless solutions, Bluetooth, ZigBee, RFID, etc., or even optical.
On our cars, you could perhaps fangle wireless sensors that would be mounted on the 'bridge' portions of a Spitfire crankshaft spanning cylinders 1-2, and 3-4,
as close as practical to the center axis of the crankshaft.
That would at least minimize the G-loading and perhaps vibration, or even temperature issues.
It occurred to me that this is a familiar problem for which there may already be some off the shelf solutions:

Wireless TPMS monitoring system must already withstand extremes of temperature, G-loading, and vibration, and at low cost.
A 22" diameter tire going 65 MPH rotates at nearly 1000 RPM, and a TPMS sensor on a 15" rim would see about 15G of centrifugal force.
Tire temperatures routinely exceed 150F.

I searched, and found a bunch of these:

https://www.amazon.com/dp/B07449SBY2/ref=psdc_2201764011_t1_B06Y5YFZRQ
https://www.amazon.com/Pressure-Monitoring-Wireless-display-External/dp/B073R7R4V9/ref=sr_1_18_sspa?ie=UTF8&qid=1518647291&sr=8-18-spons&keywords=ford+tpms+sensor&psc=1

Each 'sensor' is located on side of the crankshaft 'bridge', as close as possible to the crankshaft centerline.
A hole is drilled and tapped on each side of the bridge, to fit the size and thread of a standard valvestem.
A pressure sensing passage is constructed by drilling a small hole from the rod journal lubrication hole into the 'bridge', with an intersecting hole to reach each sensor hole.
A short piece of threaded tube is installed into each hole, with Loctite to keep it from loosening, and then the sensor is threaded onto it.
The TPMS receiver may work outside the motor, or the signal receiver antenna can be mounted somewhere inside the crankcase, out of harm's way.

Maybe the receiver can be custom hacked, and interfaced to a display/Data Acquisition device (likely a PC).

But this could certainly be done, for cheap, but 'someone' would have to sacrifice a crankshaft in the name of science.
(I have a spare crankshaft or two!)

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