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RDMG
Dave R
Northern Virginia
(107 posts)

Registered:
04/07/2016 08:29PM

Main British Car:
1979 MGB 4.6L Rover V8

Gerotor oil pump front covers
Posted by: RDMG
Date: October 13, 2018 10:48AM

I thought I’d post a few pics of the last RV8 and early 1990s Buick 3800 front covers side by side:

C40EB26E-8A02-442F-A7B0-0A00572F1540.jpeg
16C52F15-46C3-4578-AC8E-F0DB316D51F2.jpeg
91671A1D-92EB-44A1-8C81-BA6B9D648AF0.jpeg

1998-2004-ish Rover V8 4.0/4.6 Bosch/Thor cover on the left, 1988-1992-ish Buick 3.8/3800 v6 cover on the right.

The bolt holes line up, but the Buick has more bolts around the coolant passages.
The alignment pin holes in the Buick cover are too small for the RV8 block, but can be drilled out.
Note the higher top arc in the gasket surface of the Buick v6 cover. It will NOT seal to the RV8 block without mods.
The RV8 cover has about 3/32 more space between the oil pump plate and the gasket surface.
The Buick drive gear for the oil pump is a one-piece unit with the lower timing chain gear, the RV8 is separate.
The Buick oil pickup passage is 5/8dia, using the original Buick 215-design oil pickup passage, while the RV8 has a new bottom pickup.
The Buick pump gears are smaller diameter, but thicker than the RV8.
The Buick gasket surfaces are much narrower in places.
The oil filter adapter on the Buick is one style of about a half dozen, that all are interchangeable.
The Buick has additional coolant hose fittings that would need to be blocked off or welded up.
Some Buick covers have a cam position sensor hole (this one has a casting blank only).
The oil pan mating surfaces and bolts are different, and I don’t think the Buick bolts align with the older RV8 steel pan.

Others in the Buick universe have welded the gerotor bottom half to the distributor style top half.

The 4.0/4.6 serpentine RV8 presents some problems for an MGB install, and maybe similar problems for other LBCs. The front cover and oil pan must be used together. The oil filter for the Bosch/Thor front cover must be remote using the thinnest possible adapter, or the steering rack must be moved to accommodate the earlier “interim” style GEMS serpentine covers that accept distributors (filter angle is the worst of all possible covers). The 4.0/4.6 cast oil pan also hangs lower than the front crossmember, about 1.5” (I think) lower than the older steel pan, and prevents use of the steel flywheel cover for the Buick skylark bellhousing.

Making a hybrid cover from a Buick 3800 v6 gerotor bottom and an earlier 215-style top half would allow a crank-driven oil pump with simple spin-on oil filter, a Buick-style 5/8” pickup and shallower sheetmetal pan, and a distributor.

Anyone have thoughts on where to slice a cover in half? I’m thinking I could make the cuts, screw the halves onto the block to align them, tack them together, then remove and properly weld, then sand flat on a sheet of glass. I’m generally thinking the oil passages should remain intact in one, and the water passages intact in the other.



Edited 4 time(s). Last edit at 10/13/2018 11:08AM by RDMG.


mgb260
Jim Nichols
Sequim,WA
(1915 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gerotor oil pump front covers
Posted by: mgb260
Date: October 13, 2018 02:27PM

Dave, You can do it!


MGBV8
Carl Floyd
Kingsport, TN
(3496 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Gerotor oil pump front covers
Posted by: MGBV8
Date: October 15, 2018 09:58AM

Do you have a TIG welder?


RDMG
Dave R
Northern Virginia
(107 posts)

Registered:
04/07/2016 08:29PM

Main British Car:
1979 MGB 4.6L Rover V8

Re: Gerotor oil pump front covers
Posted by: RDMG
Date: October 15, 2018 09:47PM

I don’t have a TIG welder, but I know a guy who knows a guy.

I placed the Buick v6 cover on my RV8 block, and put a few bolts in to line it up. The alignment pins are too big, so the cover isn’t flush, so it’s not crystal clear how the oil galleys line up, but here’s a pic showing the right side, by the RV8 cast-in-the-block pickup galley and the oil filter adapter:

547CEF1B-E3AB-4CC4-9BB5-E62887146357.jpeg

You can see several problem areas, particularly the high pressure galley in the cover that travels to the outside of the bolt hole, near the top (left) of the photo. There’s a similar issue on the other side of the pickup galley, some sort of small offshoot to a bypass within the adapter casting. In each case, there’s no mating surface on the Rover block and the cover for a gasket to seal between. Looking at the Buick v6 blocks, they have a much larger flat surface to work with.

The Buick cover had about 3/32 less depth between the gasket surface and the oil pump plate, so I’m wondering if a 1/8” or 3/16” aluminum plate adapter sandwiched between an RV8 gasket and a Buick v6 gasket might seal everything up, and give me the timing chain clearances I may need. The plate wouldn’t extend beyond the RV8 block more than 3/8”” or so, and only for a short distance.

The options may be:
1. Use aluminum plate to adapt the Buick cover as is, then sort out some sort of EFI (basically same as if I used the 4.6 RV8 cover I have, but no need for a remote oil filter)
2. Use a plate and TIG two covers together, dizzy-type top to gerotor bottom
3. Modify the living daylights out of the Buick v6 cover with TIG welds all over, mating a dizzy-type top half to the gerotor bottom half, and somehow closing up the oil galleys along the way
4. Do far less extensive TIG mods to a rover interim cover, which seems to cost about $300 if you can find one
5. Weld a dizzy-type top half to the 4.6 RV8 cover I have, and use a remote filter.

Alternatively, I may post the Buick v6 cover back onto EBay, and move on to other, less ridiculous tasks.



Edited 1 time(s). Last edit at 10/15/2018 10:00PM by RDMG.


mgb260
Jim Nichols
Sequim,WA
(1915 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Gerotor oil pump front covers
Posted by: mgb260
Date: October 15, 2018 10:12PM

Dave, Get gaskets for each to compare. I like the idea of an adapter plate better than cut/weld. I'd go 1/4" thick.


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