MGB Oil Sump Baffle Plate Blueprint (Fig. 6), Oil Pump Tuning & Torque Specs
MGB Special Tuning page: dimensioned blueprint of an oil sump baffle plate (20 SWG/0.036 in mild steel) with gearbox dipstick, oil pump relief-valve packing and cylinder head torque notes.
This is page 457 of a competition/tuning reference for the MGB. The top half is Fig. 6, a dimensioned blueprint titled 'Detail of oil sump baffle plate,' made from 20 S.W.G. .036" mild steel, with full fabrication dimensions (overall 10 15/32" x 8 31/32", a 5 5/8" diameter plunged hole, various radii from 1/16" to 7 3/4") and drawing number A.5786A. The text below covers competition engine and gearbox preparation: fitting a gearbox dipstick (Part No. AEC 3683) modified by cutting 2 7/16 in. and re-marking HIGH/LOW levels for the MGB gearbox; checking for the high-duty mainshaft oil seal (Part No. 22H 475); increasing oil pump pressure by packing the relief valve spring with steel packings and replacing fibre gaskets with a copper gasket (Part No. 6K 431); acceptable oil pressures (70-100 lb./sq. in., dropping to 30/40 satisfactory); checking and tinning the oil pump strainer against air leaks; machining an undercut in the oil filter bottle casting; and torque wrench settings — cylinder head nuts 50 ft. lb., main bearings 70/75, big-end bolts 40/45 (do not exceed 45), flywheel 40, gudgeon pin 25, and clutch bolts 25/30 ft. lb.
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Frequently asked questions
- What are the MGB torque wrench settings listed on this page?
- Cylinder head nuts 50 ft. lb.; main bearing nuts 70/75 ft. lb.; big-end bolts 40/45 ft. lb. (never over 45 ft. lb. or the bolts may fracture); flywheel bolts 40 ft. lb.; gudgeon pin bolts 25 ft. lb.; clutch bolts 25/30 ft. lb.
- What material is the oil sump baffle plate made from?
- The drawing (Fig. 6, A.5786A) specifies 20 S.W.G. .036" mild steel (M.S.), approximately 1/4" deep, with overall dimensions of 10 15/32" x 8 31/32" and a 5 5/8" diameter plunged hole.
- How can oil pressure be increased on the standard oil pump?
- By packing the oil relief valve spring with a circular steel packing (12·3 mm dia.) fitted in the end of the release valve cap; packings of ·100, ·200, ·300, or ·400 in. thickness, or multiples of ·100 in., can be used. The two fibre gaskets under the cap can be replaced with one copper gasket, Part No. 6K 431.
- What gearbox dipstick is recommended and how is it modified?
- Dipstick Part No. AEC 3683 (retained by rubber sealing rings); it must be shortened by cutting off 2 7/16 in. (61·9 mm) and re-marked with 'HIGH' and 'LOW' levels to suit the MGB gearbox.
- What is a satisfactory oil pressure per this document?
- Between 70 and 80 lb./sq. in. (up to 100 lb./sq. in.) is good, and pressure dropping to 30/40 lb./sq. in. is satisfactory.
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