Lotus Elan

711M block

PostPost by: seniorchristo » Sun Oct 12, 2014 10:34 pm

The engine serial number on my recent Elan purchase is 711M6015BA. Although I'm disappointed the car doesn't have the original engine, I seem to remember the 711 block is a desired commodity. The car runs like a bat out of hell. Is there a good reference for information on this block? My car is a '66 SE with Weber carbs.
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Chris Herr :)
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PostPost by: rgh0 » Sun Oct 12, 2014 10:53 pm

Hi Chris

The 711M block is the later 1600 "tall block". Never originally fitted to the Elan which always used the various versions of the 1500 "short block" from Ford over the years ( 116E,120E,681F, 701M, plus a few with the numbers ground off for some reason). The later Elans used the 701M block which was the 1500 equivalent of the 711M.

Depending on how exactly the engine has been built you will have the longer stroke crank and larger capacity as a result. You will also have a spacer at the top of the front cover or a new tall front cover to accommodate the taller block.

While all the Ford 1500 / 1600 blocks had a number of detail differences in the castings they are all essentially interchangeable (with more or less work). The big advantage of the later 701M / 711M blocks is they came with much stronger square main bearing caps which saves you from doing the line bore to fit these caps (or steel caps) to the earlier blocks

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PostPost by: seniorchristo » Mon Oct 13, 2014 12:03 am

Thanks Rohan,
I guess i'll never know what's inside until I open it up and see :D . It looks like the engine leaks oil from everywhere so that may be sooner than later. Compression is 180 on all (4) cylinders. There was initial blue smoke when first starting after it had sat idle for about 6 weeks but it mostly went away after driving for a bit. Is this typical or an indication of worn valve guides? I can't say enough how appreciative I am of the help you and others offer to board memebers.
Later
Chris :)
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PostPost by: seniorchristo » Mon Oct 13, 2014 12:20 am

I just went out side to check and sure enough it has the spacer between head and front cover. Now I'm really psyched to see what's inside. I know there is a windage tray in the oil pan from some previous service records.
Later
Chris :(
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PostPost by: seniorchristo » Mon Oct 13, 2014 12:25 am

Moderator
Sorry I meant to enter this thread in the engine forum
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PostPost by: rgh0 » Mon Oct 13, 2014 1:08 am

Blue smoke on start up or after idling for a while that's goes away as you drive is fairly typical of worn valve guides. Blue smoke that gets worse as you drive is fairly typical of worn oil control rings and / or bores. But no hard and fast rules and you always really need to look inside and measure to really know whats going on.

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PostPost by: trw99 » Mon Oct 13, 2014 9:20 am

Chris, 711M6015BA is your engine's block designation and not your engine number. For a 1966 Elan your engine number will be in the LP5###,6### or 7### series.

Have a look to see if such a number is visible on the block, intake side mount, horizontal surface.

Tim
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PostPost by: rgh0 » Mon Oct 13, 2014 11:15 am

If its a 711M 6015 block casting it will not have the original engine number from 1966 ( or should not at least) The original engine would have been based on a 120E 6015 block ( maybe with the 120 ground off)

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PostPost by: gjz30075 » Mon Oct 13, 2014 1:45 pm

If you decide to switch to the shorter block, save the crank, flywheel, pan, real seal carrier (and probably a few other bits I can't think of now) to transfer to the shorter block for a stroker build. There will be debate as to which rods to use, 125E or 2737, and pistons will need to custom but you'll have a screamer for sure with a more original look.

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PostPost by: seniorchristo » Mon Oct 13, 2014 5:29 pm

Thanks for all the info. I now know the 711 numbers are not serial numbers. The motor runs great. It has good compression (180 psi in all 4 cyls.). It seems much quicker than I remember my S4 being but that was 40 years ago. :shock: Other than some blue smoke at start up after sitting a while and some oil leaks, I have no reason to change anything.
I am wondering if the reason the car sits up higher in the front is to allow clearance for the tall block between engine and bonnet. The car is a 1966 S3.
Later
Chris
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PostPost by: gjz30075 » Mon Oct 13, 2014 5:46 pm

The stance has nothing to do with the engine to bonnet clearance. There was a big discussion on front springs recently and because its an S4, the taller springs helps the headlight height requirement, or something like that.

Engine to bonnet clearance is fixed and not much can be done about it, except some fancy motor mounts to lower the engine but there's very little room for variations from factory.
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PostPost by: seniorchristo » Mon Oct 13, 2014 7:12 pm

Yes of course. It has nothing to do with the clearance. Thanks giz :)
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PostPost by: billwill » Mon Oct 13, 2014 7:35 pm

Bill Williams

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PostPost by: holywood3645 » Mon Oct 13, 2014 8:36 pm

With 180ps on all 4 cylinders, I don't think I would be pulling the motor anytime soon. You maybe could just wash the engine down and address the oil leaks. You may be able to reduce the amount the engine leaks.

Just drive it and enjoy,

James
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PostPost by: CBUEB1771 » Tue Oct 14, 2014 12:38 pm

gjz30075 wrote:Engine to bonnet clearance is fixed and not much can be done about it, except some fancy motor mounts to lower the engine but there's very little room for variations from factory.


The PO could very well have shimmed the body shell up off of the frame to create clearance between the top of the engine and the bonnet.
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