Lucas 14CUX on a 4.6 ?

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30EK42
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Lucas 14CUX on a 4.6 ?

Post by 30EK42 » Sun Nov 03, 2019 9:00 am

I've now collected enough bits to build a 4.6 engine.
I've got a LR reconditioned 4.0 block which has been rebored, and now I've aquired a good 4.6 crank and rods.
At present it's got the late type timing chest for the coil pack type ignition, but my thoughts are fitting an intermeadiate type timing chest which will keep the trichiod type oil pump but allow me to run a distributor.

Then I can fit a Lucas 14CUX type fuel injection system as I already have most of the requisite parts.

So that's my plan.
But it could be changed.
Can the Lucas fuel injection be recalibrated to cope with extra gas flow of the 4.6 ?

From reading similar posts on here, I expect to get replies critical of my plan to use a distributor, and to change to a crank triggered system.
Well the engine is heading for a home in an old series Land Rover, so losing maybe 25 Bhp at high RPM on the ignition system isn't that important.
And certainly not worth me spending £1300-1500 on a Megajolt system.
A stand alone distributor and stand alone fuel injection system would suit me fine.
Any insurmountable problems inherent ?



DaveEFI
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Re: Lucas 14CUX on a 4.6 ?

Post by DaveEFI » Sun Nov 03, 2019 9:49 am

Can't give you an answer about reprogramming a 14CUX. But if DIYing, I'd expect to fit a MegaSquirt 2 and wasted spark ignition for under £1300. Quite a bit under.
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garrycol
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Re: Lucas 14CUX on a 4.6 ?

Post by garrycol » Sun Nov 03, 2019 11:14 am

I know of a 4.6 that runs a 14CUX injection system and standard ECU - the standard ECU programming has enough scope to provide enough fuel with the 14CUX injectors for a 4.6.

Note that the 14CUX has a smaller intake (and throttle body) than the 4.6 Thor system so may be a little restricted at high revs but for everyday use does not matter.

Why did you need to bore out the 4.0 - as a 4.0 and 4.6 have the same bore.

Keep your better timing cover and oil pump and put on a trigger wheel on the crankshaft pulley, buy a cheap EDIS 8 module with your coil packs and control it with a Megajolt controller - simple and adjustable ignition and you maintain your cheap 14CUX ECU.

Garry

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Re: Lucas 14CUX on a 4.6 ?

Post by 30EK42 » Sun Nov 03, 2019 12:09 pm

garrycol wrote:
Sun Nov 03, 2019 11:14 am
Why did you need to bore out the 4.0 - as a 4.0 and 4.6 have the same bore.
I didn't
I just happened to be lucky enough to pick up a factory reconditioned block for a very good price.
New pistons and rings too - but they're 4.0 type - and one of the new pistons has been cracked due to very poor storage.

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Re: Lucas 14CUX on a 4.6 ?

Post by 30EK42 » Sun Nov 03, 2019 12:13 pm

I should add that the 4.6 crank/rods came in a block that is known to have a bad liner - presumably the usual block cracking issue.
I really don't have the funds or inclination to go for a "top hat" conversion

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Re: Lucas 14CUX on a 4.6 ?

Post by garrycol » Sun Nov 03, 2019 1:15 pm

30EK42 wrote:
Sun Nov 03, 2019 12:09 pm
I didn't
I just happened to be lucky enough to pick up a factory reconditioned block for a very good price.
New pistons and rings too - but they're 4.0 type - and one of the new pistons has been cracked due to very poor storage.
Ok I misunderstood as in your original post you said "I've got a LR reconditioned 4.0 block which has been rebored".

The 4.0 pistons will provide a higher compression ratio when used in a a 4.6.

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Re: Lucas 14CUX on a 4.6 ?

Post by 30EK42 » Sun Nov 03, 2019 4:50 pm

Thanks for that.
I had got it into my head that I would have to buy new 4.6 pistons, but a little research suggests that the 4.0 ones will be OK with a little jiggery-pokery like maybe using SD1 heads with composite gaskets.
Of course I realise that you can read as many forum posts and magazines as you like, but in the end there's no substitute for the measuring burette.

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Re: Lucas 14CUX on a 4.6 ?

Post by garrycol » Mon Nov 04, 2019 12:19 am

There is no "little jiggery-pokery" required - they simply go straight in and you can use standard heads and head gaskets. No modifications are required.

Standard 8.3:1 4.0 pistons produce a compression ratio of about 9.5:1 in a standard 4.6.

I have a a 4.0 engine block, 4.6 crank and conrods and low comp 4.0 pistons with standard heads and gaskets in my FC 101 and it runs fine (still on carbs pending conversion to Thor specs and MS3x). Current ignition is as I described above but when i finally get MS3X sorted it will run the ignition).

Garry

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Re: Lucas 14CUX on a 4.6 ?

Post by SimpleSimon » Fri Nov 08, 2019 12:28 am

The CUX Hotwire ecu has lots of scope TVR used them from 4.0 to 5.0 displacements (yes even the 4.6) if you need it remapping to suite I recommend http://www.kitsandclassics.co.uk/ and wont charge a kings ransom unlike some, lots of satisfied TVR owners 8) dont waste money on a generic performance chip Tornado etc ,you can also use stock comp 4.0 pistons in the 4.6 block gives a CR around 10.5/10.8 IIRC
TVR Chimaera RV8 Serp & Megasquirt MS3X

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Re: Lucas 14CUX on a 4.6 ?

Post by garrycol » Fri Nov 08, 2019 2:21 am

Just a minor point - the 4.6 piston gudgeon pins are thicker walled than the 4.0 pistons (outside diameter is the same but the walls are thicker). Now the 4.0 gudgeons are plenty strong enough but as I had both the 4.0 and 4.6 pistons, I had my machine shop change the gudegeons in the 4.0 pistons over to the 4.6 gudgeons - they are pressed in and need to be changed with care as the piston can be damaged.

Garry

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Re: Lucas 14CUX on a 4.6 ?

Post by GDCobra » Fri Nov 08, 2019 5:33 pm

Have a look at:

www.Remap-14cux.uk

May help

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SimpleSimon
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Re: Lucas 14CUX on a 4.6 ?

Post by SimpleSimon » Sun Nov 10, 2019 11:41 am

GDCobra wrote:
Fri Nov 08, 2019 5:33 pm
Have a look at:

www.Remap-14cux.uk

May help
That guy mentioned on the link above Jools (Spitfire4v8 is the owner of the mentioned company above hence why I posted this up previously :mrgreen: I dont recommend anyone I wouldn't use myself as I am also in the motor trade 8-)
TVR Chimaera RV8 Serp & Megasquirt MS3X

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