The MGA With An Attitude
Transplanting the MGB 18V Engine into the MGA - PP-201B

Someone didn't get it from the first article, so here's a consolidated list specifically for the 18V engine transplant.

1.) Use the engine rear plate from the MGA that goes with the MGA gearbox. Bore out the center hole to accept the MGB engine rear seal. During installation, use RTV to plug the original drain slot in front of plate.

2.) Use flywheel from a 1964-1967 MGB.

3.) Use gearbox front cover and clutch release arm from 1962-1967 MGB. Pivot bolt, rubber boot, slave cylinder and pushrod do not change.

4.) Use MGB clutch pressure plate and release bearing. See notes on MGB clutch transplant and possible interference inside of bellhousing (at bottom of that page).

5.) Use the clutch disc that matches your gearbox input splines (10-splines for MGA 1500 or 1600 gearbox, or 23 splines for MGA 1600-MK-II gearbox).

6.) Install adapter bushing for spigot bushing in rear end of engine crankshaft to mate large bore of crankshaft to small diameter spigot on gearbox input shaft. Moss Motors sells one (for a super premium price). Or you can get one from any local bearing supply house, probably much cheaper. 5/8-ID x 1-1/8-OD x 1" long. See item 12 below.

7.) Use engine front plate 1955 to mid 1974 to fit rectangular engine mounts.

8.) Use the electric tachometer from '65-'67 MGB (because the 5-main-bearing engine does not have a mechanical tach drive). This tach is originally for positive earth. If you car has been converted to negative earth, then also convert the tach to negative earth.

8.) Use the original MGA starter motor. May need to grind a bump off side of 18V engine block.

10.) Use a short nose water pump.

11.) Possibly shim radiator forward up to 1/4".

12.) Spigot Bushings:
MOSS # = BMC# = Description
330-160 = 1G765 = 13/16-OD x 5/8-ID x 11/16 long (for 3-main crankshafts)
330-420 = 12H1630 = 1-1/8-OD x 1-1/2" long (5-main 18GB-18GF 1965-1968
330-415 = 22H1416 = 1-1/8-OD x 1" long (5-main 18GH-18V) 1969-1980

330-570 = (special) = 1-1/8-OD x 5/8-ID x 1-1/2" long (5-main 18GB-18GF to 3.synch)
= (special) = 1-1/8-OD x 5/8-ID x 1" long (5-main 18GH-18V to 3-synch)
If you cannot find a single piece bushing with wall this thick, you have two alternatives.

1.) Start with 1-1/8" OD bearing bar and bore to 5/8" ID.
2.) Use two bushings, one inside the other.
5/8-ID x 7/8-OD x 1" long -- Oilite part number = AA-880-1
7/8-ID x 1-1/8-OD x 1" long -- Oilite part number = AA-1108-1

5/8-ID x 7/8-OD x 1-1/2" long -- Oilite part number = AA-880
7/8-ID x 1-1/8-OD x 1-1/2" long -- Oilite part number = AA-1108-12

Test or measure the bushing ID after installation. Should have a couple thou clearance, slip fit with a drop of oil. If it is tight on a 0.623" shaft, then hone or burnish to size or run a 5/8" reamer into the bushing.

13.) Test fit gearbox to engine after installation of all clutch parts. Test rotation and function of the clutch before installation in car. Refer to item 4 above.

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