Dating the Block

Locating the date mark, relatively easy with no emissions kit and the inverted oil filter:

Although a Gold Seal engine the engine number prefix of 48G is correct for the 1972 year of manufacture of the car, and appears to be pattern D, week 17, 1972:

An 18G 3-bearing engine, just a '2' where the clock would be i.e. directly under the oil filter housing position. '12H750', some odd numbers higher up. The flange under the dip-stick hole is full length:

Probably pattern E or F, week 13, 1966, with an engine number of 18GB i.e. 3-bearing. Three '12Hnnnn' numbers, and 'AF2'. Flange under the dip-stick hole only going forwards:

Another 18G/Gx block with the same three '12Hnnn' numbers as above, but this time 'AF1'. Date clock indicating 1967, so an 18GB or GD (Ryan Foster, USA):

This engine has 1970 on the dating clock, so an 18GG to GK, but a single 12H3248 casting number and 'AF5' (Mustang Shire):

A five-bearing 18GH (from the engine number tag, so Oct 68 to Aug 70), again no clock or anything else under the filter, very different numbers at the left including '12H3508' but no 'AFn' number, and rectangular bosses for the sump screws instead of rounded:

Probably pattern L, week 29, 1973. Engine number and originality to car not known.:

And yet this 18V673Z (going by the engine number tag) i.e. August 72 to September 74 has no clock:

Barely legible - but the year digit looks more like a 5 than a 6, the engine number dates to about October 76 so the casting could be from late 75 or early 76:

An 18V block with '12H3508' on two rows and 'AF1', and a date clock indicating 1975, i.e. an 18V 846/847, 18V 797/798, or 18V 801/802. None of the other markings as on the previous engine. Back to rounded sump screw bosses(Jim Bronson, Canada):

I've seen two examples where CAM1628 replaces the 12H numbers, with date wheels showing 1975 and 1976. (John Fraioli):

An 18v883 of Jun 76 to Oct 80, clock with a single '7' indicating 77. The same '12H3508' (but on a single row) as above, and 'AF5':

The 18GB, 66 dated block (as in the top picture on this page but before degreasing) with no position for the mechanical fuel pump:

The 18GG to GK 70 dated block again with no position for the mechanical fuel pump (Mustang Shire):

The fuel pump aperture on an 18V block dated 73 and 12H3503 (Duane Timbers, Canada):

An odd one this, block of unknown date or origin, has the long oil gallery rib of the 18Gx engines with the moulding for the fuel pump underneath it. (MGA Guru with an attitude):