Which Block is suitable for a Twin Cam?

[l10tus]

Just a question about suitability of the Engine Block.

In an effort to build a standby TwinCam engine, which Ford Blocks are suitable and readily convert into the Twin Cam.

I have an Head awaiting.

Don't really want an oversized one, but that would be acceptable if the conversion is reasonably straight forwards.

Does it matter if it's the 1500cc pre Crossflow motor, the 1600 Crossflow or whatever ?

Does it need to be the 7011M block or will others suffice?

What's the general availability like in obtaining the correct block ?

Any suggestions would be appreciated,

Regards,

Phil.

[billwill]

Not a direct answer but read these articles in the initial phase of the Wiki on this web site

http://www.lotuselan.net/wiki/Lotus_Twi ... ild_Part_1

http://www.lotuselan.net/wiki/Lotus_Twi ... ild_Part_2

And especially this one:
http://www.lotuselan.net/wiki/Torquing_ ... am_Rebuild

[l10tus]

Bill,

Fantastic reply thanks!

Just what I needed!

Looks like I need to stick to the shorter pre-Crossflow, because of the possible bonnet clearance issue ?

Thanks for the attachments,

Best regards,

Phil.

[rgh0]

Note the last wiki article has a major error in it in the statement below.

"Lastly you can machine the Crossflow block to correspond dimensionally to the Lotus Ford 'L' block. This for all intents and purposes will give you a replacement "L" block. If the Ford block is thus machined then a Lotus or 1500 crank and rods will need to be reused. Obviously because if the 1/2" inch is removed from the block deck height, then the pistons will be sit proud of the face if assembled with the Crossflow rods and crank. Even though most people desire an increase in compression ratio, this is going to the extreme".

You cannot reduce the height of a 1600 cross flow 711M block to that of the 1500 blocks as used by Lotus ( i.e. 116E, 120E, 681F, 701M) by machining 1/2 inch off the top - That will remove all or almost all the metal from the top deck and result in an unusable block.

cheers
Rohan

[billwill]

We will have to hope that Jeff will soon release the Wiki for members editing so that you can fix that article, Rohan.

[l10tus]

Bill, Rohan,

Thanks for the replies.

Does that mean that all the 1500 blocks are of the correct deck height ?( so would be usable as is, without any machining -other than a light scim to clean up the face if necessary?)

Also, confirming that all versions of Crossflow blocks are too tall for use in the ?lan? - because of reduced bonnet clearance?)

Thanks,

Phil.

[billwill]

It isn't necessarily a problem is it?

The article in the third link says:

If an engine is rebuilt using a taller 1600 block then engine mounts and bonnet clearance will need to be checked.

Due to the additional 1/2" on the 1600 Crossflow block exhaust side mounting bosses, the original mounts will not work as they will be spaced out the additional 1/2". This additional 1/2" can be machined down off of the block mounting bosses, certainly a nice & tidy solution. If this is not possible the original engine mounts can be modified or replacements made.

The bonnet clearance is not a problem for Europas, Escorts and Cortinas. However for Elans and Sevens any additional engine height can lead to the cam cover fouling the bonnet. If this is the case then you may have to manufacture some new engine mounts. There have been articles written where "spacing" the body off of the chassis has been suggested. This does seem to be a rather crude solution, and would no doubt lead to body/chassis problems latter on. For this reason new or modified engine mounts seem far more sensible at what must surely be no additional work in comparison.

So you might need to have the engine mounts altered slightly. I think Rohan has mentioned cutting slots instead of round holes so that the engine height can be "micro adjusted"

It shouldn't affect the problem of the carbs hitting the top of the footwell because the taller block will have lifted the head and hence the carbs by a half inch anyway.

[rgh0]

The original Lotus Twin-Cam engines all used standard Ford 1500 blocks. The L or otherwise is not significant and did not affect the actual casting versus the non L equivalent block as far as I can tell. The taller 1600 blocks can fit in an engine bay Ok. The height fit to the bonnet is tighter on a Plus 2 than Elan but with some playing with the engine mounts you can get the clearance needed with the bonnet so they can be used. However using the taller 1600 block requires some other adjustments with items around the pistons and rods used and front cover and timing chain to accommodate the taller block and with the engine mount spacers to accommodate the wider dimension across the block for the engine mounts all of which are practical to do.

cheers
Rohan

[l10tus]

Bill, Rohan,

Thanks for the info.

Just wondering if the 1200 block &1300 blocks can be bored to Twin-cam diameter ok?

Or is the 1500 / 1600 size recommended?

Regards,

Phil.

[types26/36]

The 1200 and 1300 could be bored to the same bore as a TC but you would still end up with a 1200 or 1300 engine so not really of much use, not only that the 1200 is a three main bearing engine so that it would be a waste of time.
As I recall I dont think you can get a1500 TC crank into a 1300 block to stroke it due to the throw of the crank and even if you could you would need special pistons and rods.......dont waste your time with 1200/1300 stuff.
Basically you need a preXflow 1500 block or a 1600 Xflow with a few mods.

[l10tus]

Brian,

Thanks,I appreciate what you say.

Now, I just need a 120E block, crank and rods ...........

Regards,

Phil.

[types26/36]

[quote="Now, I just need a 120E block, crank and rods ............[/quote]

Well the normal 120E has skinny conrods and a four bolt crank, you would be better off looking for a 6 bolt Lotus crank and 125E conrods.......plus the sump and flywheel to suit.
You can build it with all that early stuff but it would be a bit out of place in a Sprint.
........but than again so would a 120E.....

[cal44]

Just buy a new L block from Ford.......problem solved

[Keith Scarfe]

Just buy a new L block from Ford.......problem solved

http://qedmotorsport.co.uk/qed-shop/lotus-twin-cam/cylinder-block-components/681f-l-cylinder-block

Maybe first win the lottery.

[gjz30075]

They're all over ebay
http://www.ebay.com/sch/i.html?_from=R4 ... k&_sacat=0

Much cheaper, even with shipping