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Thread: lotus/ford twin cam

  1. #1
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    lotus/ford twin cam

    A bit of a departure from the norm for me. i started out building a x/flow, then a flat top piston-ed x/flow, now its morphed into a twin cam, but its anything other than straight forward, its got to be road legal in another country so as soon as the decision to use a twin cam head was made the x/flow block couldnt be used, instead the owner sourced a 1500 pre/xflow bottom end with a "L" casting block, so effectively we are building a twin cam which never existed from bits only, although we are retaining the x/flow crank, so we are going to end up with a pretty non standard twin cam.



    a big wing sump was sourced, but that had three problems, 1 it had a fair few dents, 2 it didnt come with an oil pick up and a standard pickup doesn't fit, and 3rdly, it was very dirty internally in the wings, try as i might, i couldnt get it clean, so end up cutting holes in it to clean it properly, that did give an added bonus in that it made it easy to make a standard escort pick up pipe fit


    once i was sure it was a clean as possible to get i plated over the holes, for this i bolted it to the block and brazed plates over the holes, braze is excellent for this as it flows nicely, its basically high temperature soldering so water tight



    Last edited by Graham; 10-03-2019 at 23:54.

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    Re: lotus/ford twin cam

    Interesting to know what you'll do with pistons for it as even if you use Lotus rods and pistons with a 1600 crank you'll still have pistons poking out slightly. You could marginally shorten some of the late type large cut-out pistons if not going too wild on cams.
    The block will probably need careful relieving around the con rod clearance pockets in the block - these can and do go through here! It's more the con rods that catch but also the TDC indicator (for re-grinding purposes) on a 1600 (I think it's on the 2nd big end journal) will also catch the STD bore bottom.

    I have a genuine pickup pipe for the big-wing sump - it's amazing how many are for sale with the incorrect pick-up pipe - I have a feeling that's why the sumps change hands regularly!

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    Re: lotus/ford twin cam

    we have a set of domed low compression height pistons, for use with long rods, and some not quite "long" rods, which in a trail build nearly worked, it left the pistons a bit down the bore, so we have now moved onto a set of custom made rods, well we will when they turn up.

    despite what two twin cam experts told me, when i did the first trial build the block didnt need any clearancing at all, i just had to grind that TDC indicator off the crank. that may of been down to the steel rods that were used
    Last edited by Graham; 11-03-2019 at 08:28.

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    Re: lotus/ford twin cam

    Should make for a nice engine if you've got slightly longer rods than the xflow length rod. Steel rods do tend to have a lower profile on them just above the con rod bolt hole so that's a nice way to go that you don't need to modify the block.

    Has the owner decided on spec for the head and cams?

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    Re: lotus/ford twin cam

    yes he bought the head in already modified/ported by nick stag and fitted with QED 420 cams

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    Re: lotus/ford twin cam

    Quote Originally Posted by Graham View Post
    yes he bought the head in already modified/ported by nick stag and fitted with QED 420 cams
    Can't go wrong with Nick Stagg stuff! Should be an interesting engine when done!

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    Re: lotus/ford twin cam

    thanks Graham for taking the time to show your work.

    Please keep up showing all your great work if time allowed.

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    Re: lotus/ford twin cam

    Quote Originally Posted by HonkyWhiteTrash View Post
    Can't go wrong with Nick Stagg stuff! Should be an interesting engine when done!
    It took a while, but head turned up to be work of art.

    Purchase head from a member in here and sent it to Nick Stagg for full rebuild

    Head spec:

    1) Full set of valve seats
    2) Bronze guides
    3) Cam bearings and the required studs and nuts
    4) QED 420 cams
    5) Cam followers
    6) Full spring pack that will include collets,platforms and retainers
    7) Competition valve set. 1.625/1.400

    fully port and gasflow, hardened valve seats, bronze valve guides , shim cams, new studs and paint

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    Re: lotus/ford twin cam

    a few pictures of head
    Attached Thumbnails Attached Thumbnails LOTUS_HEAD.jpg‎  

    LOTUS_HEAD1.jpg‎  

    LOTUS_HEAD2.jpg‎  

    LOTUS_HEAD3.jpg‎  


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    Re: lotus/ford twin cam

    Lovely, doesn't come any better!

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    Re: lotus/ford twin cam

    Quote Originally Posted by HonkyWhiteTrash View Post
    Lovely, doesn't come any better!
    I agree, but the most important is to find someone to build it right.

    Even sourcing many parts from twin cam experts, Graham spotted numerous issues with parts and the build.

    Graham also sourced the correct parts for me offering improvements for both reliability and to be able to extract the most out of this engine.

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