Block Casting Info wanted

[tonyabacus]

Engine block info wanted for the engine recently installed in my car. It is not the original engine when the car was built, but can someone throw some light on the various casting marks on the block please.

I cannot see the side of the block on the right hand side, so cannot see if it has an "L" cast into the mounting area, but are all 681 Blocks stamped as L blocks. With the engine installed it is not possible to see, but no doubt you will know the answer.

Also I also took a look at the casting date, but again it has thrown up a conundrum as it seems to read M302, which does not look correct (the code is covered in thick paint making it unreadable). There is a casting clock above this date shows the arrow pointing to 4 on the clock, but what is the significance of the clock?

So is anyone able to explain the various casting marks and their significance please, Tim has indicated that the engine number is for a 1970 +2S and as my car is a 1970 Elan SE, it seems the replacement engine was manufactured around the same time, but it would be useful if I can decipher the casting marks for clarity.
Thanks
Tony

[trw99]

Hi Tony,

Sorry I did not come back to you on this - I have been away a lot over New Year and returned from Manchester last evening.

I hope Rohan does not mind if I set out below some of his learned writings on the subject of engine blocks. He has studied them assiduously and knows much more about them than I do! I dare say he will chip in later.

"Casting date on engine block:
1st Character = Year within decade. 2nd Character = Month, A=Jan (No I used) 3rd Character = Day.

Engine introduction dates:
The 116E block was used for the earliest twin cam in late 62 and early 63 but changed to the 120E block when it became available - nominally in October 63 according to the listing below. Not all these engine type numbers actually had their own block numbers

Anglia (997cc engine) 105E - Introduced September 1959

Anglia Super (1200cc engine) 123E - Introduced October 1962

Anglia Van (997cc engine) 307E - Introduced June 1961

Anglia Van (1200cc engine) 309E - Introduced June 1961

Prefect (997cc engine) 107E - Introduced October 1959

Consul Classic (1340cc engine) 109E - Introduced May 1961

Consul Classic (1500cc engine) 116E - Introduced August 1962

Consul Capri (1340cc engine) 109E - Introduced January 1962

Consul Capri (1500cc engine) 116E - Introduced August 1962

Consul Capri G.T. (1500cc engine) 116E - Introduced February 1963

Consul Corsair (1500cc engine) 120E - Introduced October 1963

Consul Cortina (1200cc engine) 113E - Introduced September 1962

Consul Cortina Super (1500cc engine) 118E - Introduced January 1963

Consul Cortina Lotus (1558cc engine) 125E - Introduced January 1963

Consul Cortina G.T. (1500cc engine) 118E - Introduced April 1963

Note: For left-hand drive vehicles add "1" to the model number, for example 116E becomes 117E etc.

For Reference: 3014E 1300 DeLuxe MK2, 3016E 1500 MK2, 3018E 1600 MK2, 3020E - MK2 Cortina Lotus

The LA LB LAA numbers stamped on the front face represented Lotus or Fords or the various engine assemblers that Lotus used relatively crude attempt at block grading using special callipers through the various core plug holes to measure the wall thickness at a few points. The code is described in Wilkins book. It is the only block actual measurements from the original casting and machining and gives a rough indication of wall thickness. My personal interpretation of the somewhat cryptic comments in the Wilkins book are:

LA blocks OD of bore casting at top end of range - around 91 to 92 mm in my experience
LB blocks OD of bore casting at lower end of range - around 90 to 91 mm.in my experience
LAA top end of casting but some sort of machining problem so the second A added after machining.

LA block good for bigger bore engines. This is generally true but depends on how well the bore is centred in the casting and whether offset boring can re-centre it and how representative their spot measurements were. You really need a full survey of each bore with ultrasonic measuring to know what's possible in terms of boring out a block.

The Lotus original stamping e.g. LA / LAA / LB was based on a couple of thickness tests using special callipers through the casting plugs so it was only a rough guide and while it detected potential castings that could be bored larger than the Lotus standard 82.55 it failed to detect many that met the criteria these days based on a more comprehensive ultrasonic bore scan. In practice I see no real difference between new ford motor sport blocks and original blocks, non lotus original ford blocks, or L blocks and between LB blocks and LA blocks though I have only ever measure a couple of LA blocks. The casting technology is the same on all of the blocks and this limits the bore wall thickness to the range I have tested and any block may be thicker or thinner due to random variation in the actual casting.

Cylinder heads:
On the rear face of the head there should also be a stamped number of format normally AANN which is some date or batch coding for the later heads that Lotus stamped on the heads when building the engines. This two letter and two number stamping appears to have started when Lotus brought the engine building in house around 1968. Earlier heads had the engine number stamped in the same location, some heads have nothing.

Some heads have the engine number stamped on the bottom face. The other cast numbers on the bottom face of the head are Lotus and WM (William Mills the foundry that cast them) part numbers and some other casting date or batch code that WM used when doing the casting."

And below is an article published by one of the Lotus clubs in the US, but half hitched from the LoCort Register, which may be helpful too.

Tim

[rgh0]

The 681F block came in both the 1500 height used by Lotus and 1600 height used by 1600 Cortinas. I dont know if all the 1500 height blocks had the L by then but they may have had it to help distinguish them from the 1600 height blocks in the foundy and machine shop ? Were Ford making the 1500 block for any other cars or uses but Lotus at that time ? L blocks are found in some old 1500 Cortinas as they were being supplied by Ford as replacement parts when they stopped making non L 1500 blocks for themselves and were only making 1500 blocks for Lotus. Exaclty when that occured i dont know but its was around the 681F block time

cheers
Rohan

[2cams70]

As far as I can establish all the 681F 1500 cc height blocks had “L” s on them. No regular pushrod headed 681F blocks in 1600cc height ever had an “L” on them. Pushrod headed 681F 1500cc engines we’re never used by Ford in production.