P400 Sump Separation Conversion

only 50 late model Miura SV were fitted with factory split sump. This means the preceeding 700 Miura were shared sump. Making this conversion was important in 1975 as the Miura was a rat road car, flogged for daily use. Making this conversion in 2008, for a car that is now automotive art and driven monthly is still not a bad idea based on the substandard , modern lubrication oils available for engine (API SL/SM) and transmission.
any help on this please, thanks - p400@comcast.net
Modifications required -
1) plug 5 holes in engine block assembly.
2) seal 2 rotating shafts in the transmission.
3) seal 3 shift shafts.
4) provide ventilation.
5) provide oil level control.
This is not a modification to be undertaken by an owner or shop that  cannot show prior success with this exact Miura work.
This is a permanent, value threatening or value enhancing modification.

1a) plugging the obvious 4 holes in engine block.
- The four oil ports in the block must be sealed off  with appropriate alloy plugs, tig welded in place.

1b) plugging the fifth hole
- The rear head drains oil back onto the trans shaft thru a drilled  hole in the trans/engine wall.
This oil port needs to be plugged.

1c) drilling the return port thru to the engine
- it is obvious the return port could be drilled thru as the others to exit at the crank area. It has been found that the wall thickness varies and the drilling of this port may break back thru to the transmission. If this happens, a long, thin aluminum sleeve can be fabricated to restore the port and assure the head oil drain makes it back to the crankcase.

2a) sealing the lower transmission shaft
-fabricate cutom plug.
-modify engine block to accept new seal plug.

2b) sealing the upper transmission shaft
-drive gear modification to accept lip seal.
-plate modification to accept lip seal assembly.
-seal adapter plate fabricated and installed.
-appropriate lip seal.

2c) left hand thread end lock requires seal modification.

3a) sealing the 3 shift shafts
- the three shafts require a cover plate to seal them. appropriate design to avoid hydraulic/pneumatic lock is required.
- The new cover causes the engine end housing  a fit problem. engine cover requires permanent modification.
The primary gear cover will need to be machined to allow for plate cover over the three shafts. See A in photo.

4a) venting the transmission / differential
- tap existing trans top plug for banjo fitting.
- install vent hose.
- filter?

The engine pictured is an early SV type. The sump is being split and a vent is found installed at the shift housing. A tapped hole in the shift shaft  installation cap plug. nice job. This vent might require some heat shielding as well, maybe silicone core tubing, TFE core might not fair well as this is very close to headers. Banjo fitting, non-AN fittings make a nice period installation and like you didnt shop at Earls.
(Joe Sackey photo)

5) split sump transmission oil level
- tap the trans housing for level plug.
- install appropriate plug.

There is a new cast boss area on a late SV transmission case.
Having this boss area can confirm an OEM split sump engine.

Several Bob Wallace modified Miura have been observed to have had
the level plug added to the transmission cover plate as shown.
This modification requires a "level plug boss area be added".
Then drill and tap the boss area for a 20mm drain plug.
could be a gasket.
could be safety wired.

Additional info-
transmission/differential oil type, brand, weight

A problem created or worsened by sump separation is low oil flow at primary gear train. Starter gear, crank gear, idler gear, trans input gear set. This is usually solved by adding appropriate hardware to collect oil from foward cam and rearmost cam ends and plumbing it to required locations.
See item #2 in the photo under venting the trans, see AN fitting installed to allow for plumbing to rear gear set, trans input.

Collected comments from VLG 2006
What do you mean 'split sump'? Folks here in this thread have talked about separating the engine oil from tranny/diff oil, and they have talked about lowering the sump to prevent starvation during hard cornering. Separating the engine oil from the tranny/diff is an unproven, but looks good on paper mod. I had it done to mine. I find it hard to believe that the 20W-50 engine oil can protect the gears, and take the loads, in the tranny/diff as well as a proper 75W-90 gear oil can. But many of these cars have covered a bunch of miles with no issues using the engine's oil as lubrication. The gears in my tranny looked fine after about 30k miles. But I took it appart since somebody missed a shift into second, before I bought it, messed up the syncro's and I couldn't get it into second. Folks were still impressed on how quick the car was even though I shifted from 1st to 3rd. Some didn't even realize I had skipped a gear.  While in there I found the shift selector forks well worn from what I was told was folks holding onto the shifter while driving. But all the gears looked good. I also don't want pieces of the tranny/diff ending up in the engine oil, not that much is really generated. Also there is nothing filtering the oil before the pump and I question how good the filtration system is. I suspect this is more of a feel good mod, although not a lot of work. If I remember what Bob told me he did was basically, weld over the 3 holes in the casing, between the tranny and the engine sump, and machine the case and tranny input shaft to add a seal. While he was in there he also machined the case to add a double row bearing on the diff input shaft, he felt that the existing bearing was under sized for the loads it saw. Lowering the sump to prevent oil starvation is a different can of worms. I have, more often than I care to admit, cornered my car hard enough to have the oil pressure drop to zero. I am not sure how it could be sensor/gauge related. I believe that doing something to prevent that is a good thing. Is lowering the sump the right way to go? I'm not so sure. I had Bob W. do this mod to mine.. but I have not driven it since, so I don't know the full benefits, if any. I DO NOT like the fact that the oil pan now sticks out below the belly!!! One of the things Bob does in this mod is to add trap doors on the oil sump to hold the oil into the center of the pan during cornering.. I think this is a good idea. The other option is something like the Accusump to help maintain oil pressure during cornering, but that has it's own issues. The other option is to just slow down and not drive so fast... NOT!
Happy Holidays to all,  Jim Peck  Miura 3036

Jim, I had Bob Wallace rebuild my Muira 4791 and he did the mod to isolate the two oil types and added the spacer to lower the oil pan. The clearance issue of the lowered sump was always a concern and I was always was on the lookout for elevated manhole covers! He also did a mod that had braided steel line running from the heads to the block. He was concerned with too much oil on top of the engine at high revs. Have you considered this mod? Mark , Miura 4791

It sounds like you are either about to assemble an engine or start an engine overhaul.  That’s certainly the perfect (only?) time to go to the trouble of separating the sump.  The attached images from my 71 SV engine show some of the details (engine was modified using Bob Wallace’s procedure circa 1987).  I spoke with Jeff Stephan about this last week.  Here are his comments:  1.Plugs need to be tig welded in the septum separating the sumps. 2.A filler plug needs to be added to the trans (done on the gear cover plate per Wallace)   3. The input shaft needs a seal. (Jim previously pointed this out)   4. The lay shaft is supported in a clear-through hole that would allow oil to pass through the bearing.  The hole must be blocked  5. A breather must be added.  The late SV engine castings were not only modified to separate the sumps, but also a reinforced (4 quart level) overflow drain was added .  (Yes, the factory thought this was a worthwhile project!).   Best regards, Greg,  Miura 4142

Mark, I don't remember any discussion of excess oil on the top of the engine. He did add a braided line from the oil pressure feed at the top of the block over to the casing where the transfer gears are to better lubricate them.    Jim

Items of interest  - (what a fortuitous photo!) -
Engine A is an early Miura most likely #2400 or earlier based on several things - carb vents, sump bottom plate, drive hubs, etc. This early engine appears to have been converted to a split sump, based on the placement of a new level plug in the location of a very late model SV.
Engine B is a very late SV, one of the last 50 most likely, and it has a split sump based on the sump level plug.

Engine A has the early, shallow sump bottom plate, so this would indicate that no oil slosh modifications have been made. No oil drain tubes have been installed to pipe oil form the head ends to the primary drive...........so just a split sump.

Engine B has the extended sump spacer, later deep sump bottom plate (OEM on this engine), oil drain pipes which appear hard piped. I would expect this Miura engine to have the slosh modifications internally as well.