Lotus Elan and Lotus Elan Plus 2 Forums

Thanks for that Tim. There really is only just enough room to fit P12916LA-A on that boss with the large stamps used, perhaps they left out the spacing.
I can make no sense of the 036/1 number on the reg doc, it does not tie in even with the "Spence" number on the cam cover, which, with a bit of imagination can be seen to encompass the Lotus engine number 12567? Although Shirley that would have been even earlier?
At some point the engine will be coming out and then I'll be able to look on the rear of the head, to see if there is an engine number stamped there.

Any more thoughts, chaps?

elansprint71 wrote:Thanks for that Tim. There really is only just enough room to fit P12916LA-A on that boss with the large stamps used, perhaps they left out the spacing.
I can make no sense of the 036/1 number on the reg doc, it does not tie in even with the "Spence" number on the cam cover, which, with a bit of imagination can be seen to encompass the Lotus engine number 12567? Although Shirley that would have been even earlier?
At some point the engine will be coming out and then I'll be able to look on the rear of the head, to see if there is an engine number stamped there.

Any more thoughts, chaps?

The plot thickens.... Andy Graham at Lotus has told me that the kit was shipped with engine number L18647.

Just spent the day stripping a 120E long engine with an L cast in at the appropriate place.

This engine came from my Lotus Elite series 1 which had had an engine transplant in the USA back in the dark ages. I pulled the engine out some 14 years ago in late 1998 and put it aside when I built and installed a Climax.

A few years ago I was moving the engine and it was then I realised the engine was built around an L block a T3.

As I now have 3 cars with twincams, 2 Brabhams and a series 1 Elan, I thought I would start the process of building a spare around this block, starting with stripping it bare. I always imagined that seeing the Elite was a Lotus they had sourced a Lotus engine and put a non-crossflow head on it. Well, first disappointment was ordinary pistons, no eyebrows. Next disppointment was 116E crankshaft and rods. Next disappointment was bore size 81 mm. Next and last disappointment was only about 3mm meat measureable in the rear wall of the rear cylinder, not enough to get 82.5 even.

So it would appear occassionally a block cast with an L was realised to have too thin a wall thickness to use as a Lotus and it was sent down the normal assemby line as a normal production block and only bored to 81mm

Almost 50 years later we learn a little more - anyone else ever found an L block with only 81mm ?

Going to list it on E-bay as might be useful to someone from an originality point of view - but it will have to be sleeved. I have searched all over it but cannot find an engine number on it. It still has 120E-6015 embossed on the side.

Ed

EdHolly wrote:Almost 50 years later we learn a little more - anyone else ever found an L block with only 81mm ?

Yes. Info here.

http://www.lotus-cortina.com/library/block/blocks.htm

Read all the highlighted links to get a fuller picture although it's 2005 info.

There may be something later.

Certainly my 701 L block was 81 before I had it bored to standard 82.5 twin cam bore

Also have 81mm L block on a T3 cast, came out of a 1500 corsair it's all greased up & waiting for it's day Curly 1964 s2 26Rrrr

EdHolly wrote:Just spent the day stripping a 120E long engine with an L cast in at the appropriate place.

. Next and last disappointment was only about 3mm meat measureable in the rear wall of the rear cylinder, not enough to get 82.5 even.


Ed

Hi Ed
With offset boring it should be quite practical to get an 82.5 mm bore out of the block - the wall thickness on the front of the rear cylinder you should find is much thicker and you can bias the boring to take essentially nothing of the rear wall and maintain most of its 3mm minimuim wall thickness.

cheers
Rohan

Just on casting numbers at the late end, my March 1972 build Twin Cam Escort's engine is built on a 710M6015LA casting with the "L" in the engine mount and is a T2 example (from memory it's stamped LA on it's front too) - it's at plus 60 at the moment, tired and emotional after having done a lot of miles since it's last rebuild.


- I've always presumed that the 681 blocks came in with the change from rope to lip seal. I've got a spare L blocked Twin Cam Escort engine (that I've not dissected yet, but am pretty confident it's out of an Escort as it's got the correct "winged" sump and is on an earlier 681F6015 N/A block and is a T1 example - I don't know what grading stamp it carries). Edit 23 July 2012 - It's got J 22130 stamped on the flat between the distributor and fuel pump sites. Will check for grading and head numbers in next couple of days...........

How plentiful were the 116E blocks compared to the120E back in the day? I've only seen one 116E in the flesh, & I've never seen a 122E block either, though these days some people refer to any Cortina Block as as 116E, which can be misleading.............

Yeah Ed, keep it and keep as much meat in it as you can, run it small bore!!!!!

Cheers

James

Hi James

My guess is one 116E block to about twenty 120E blocks - based on my sampling. I to have just one 116E block in my collection currently.

Never seen a 122E block either

cheers
Rohan

My guess has long been that Ford moved to 120E castings fairly early on. Racing car magazines in 1968 were referring to the standard engines for bespoke racing cars as the "116E" and that would have been years after the 120E blocks had gained wide circulation, as a stab in the dark I'm guessing that 120E blocks could have been produced in 1965, or even '64?

I presume that once 120Es started appearing, 116Es ceased production.

SJ Lambert wrote: is a T2 example (from memory it's stamped LA on it's front too) -
James

Hi James - despite what is written by some I have never managed to find any correllation with the T number and wall thickness in the many 1500 and 1600 blocks I have measured. To be specific I have never found any correllation between bore casting outside diameter and thus wall thickness and any of the various casting and T numbers. Bore casting outside casting diameter variation is random within a narrow band dictated by the sand casting technology used by Ford. Sample lots of blocks with an ultrasonic guage and you will always find a few of any type that can can take a bigger bore.

cheers
Rohan

Wasn't it suggested not so long ago that the 'T' number was a casting batch number?

It would seem to make sense following Rohan's extensive research.

For interest, the block I bought in 2002 from a local engine man who was retiring was numbered thus:-

701M 6015 BA
No. 118E 665088
Ford BA L T1

Make of that what you will!

I reckon Rohan's correct. Our largest bore engine is on a T11 and is at 85mm, Holbay put it together back in 1965.

Anecdotally, it seems like the three bearing blocks used in the Formula Juniors have had an easier time of it getting to 85mm throughout.

Just to add my bit to the discussion, the wall thickness of the standard bore 120E6015 block I am using varied from 4.5mm to 6.0mm. It is a 'T4' non 'L' block and as far I remember the offset was consistent across all four bores. I have not been able to compare these thicknesses with the desirable 701 'L ' block but someone can I am sure. However as Rohan has advised using offset boring would certainly get the best from this block if larger bores were needed. Perhaps Lotus were not prepared to do this so limited their recommended oversize to just 15 Thou.

Those wall thicknesses are at the upper end for a block with the OD of the bore casting around 92 mm OD. "701 L" blocks will not be any different. The offset in the casting versus the standard bore is fairly typical also.


cheers
Rohan

EdHolly wrote:Just spent the day stripping a 120E long engine with an L cast in at the appropriate place................

..............as might be useful to someone from an originality point of view - but it will have to be sleeved. I have searched all over it but cannot find an engine number on it. It still has 120E-6015 embossed on the side.

Ed

Thanks for letting it go Ed!! I'll try and get up to you over weekend of 7/8 July or even 14/15 July to pick it up (the dearest bride may not rank the priority of the road trip to bring the latest edition to the Lambert 120E family into the fold as highly as I do!!)

- I'm still quite impressed that Ford cast the "L" into any of their 120E blocks. It's only on this thread that I've recently realized that there were any so cast. My assumption was that they only started casting them when they moved over to lip seal cranks and the blocks that accompanied them in 1967. Miles Wilkins book even states that the move to Hethel (for Lotus) coincided with Ford's update of the engine for the Mk 2 versions of the Cortina and "the blocks were now specially cast for Lotus, having a large 'L' cast into the right hand engine mounting area."

It seems then that L blocks could well have appeared a year or two earlier. Which is a little curious as I wouldn't have thought that thin walls would have begun to be a problem by then, perhaps it was done in part for kudos and in part with internal core boxes that were expected to consistently produce the desired result?? - Or maybe Ford were casting them especially for Lotus earlier than I realised just with a view to higher quality control for those ones............

Wilkins also says that it was Ford that graded the blocks for Lotus with the ubiquitous LB, LA or LAA grading - it seems as though whether this one got a grading or not (is it stamped on it's front Ed?), that it got sent down the iron head line, as you say!! - It may yet get a Lotus head one of these days as it might just clean up in it's small bore guise and serve as a backup block to our 1966 Cosworth Mk16 (ANF 1.5) Twin Cam engine - if it's got enough meat in it to be used as is, we'll continue to run it as a quirky small bore engine!

Cheers

James