My 4.6 V8 Rebuild Thread

[PhilipA]

I believe you may be able to use the earlier injectors, rail and
regulator in conjunction with the THOR manifold.

It is by far the simplest ,if you want to go to injection to use a 14CUX ECU , loom and injectors and fuel rail.
You can fit the fuel rail from a RRC up to 92( I know for sure) by grinding the bosses for the coils off a Thor.
The fuel rails for later D1s are different from the RRC. the RRC has the fuel regulator on the RHS of the engine and the fuel temp sensor at the front. These will fit with a Thor but the D1 has the fuel regulator on teh LHS and the temp sensor on teh LH side and these foul the underside of a Thor.

Be aware that the Thor Motronic ECU is also tamper proof and has to be coded to the VIN. The Thor uses higher line pressure than previous systems so needs special short injectors if you don't get them with the rail, while the 14CUX will run excellently with cheap Bosch Yellow 19Lb injectors , available on Ebay.

The Thor rail has no regulator and is a "dead end" so without mods cannot be fitted to earlier injection. The Thor regulator is in the tank as part of the high pressure pump which is mucho dinero, so you virtually have to fit a Thor tank if you want to keep this simple.
The worst thing about a 14CUX is that it does not control timing. Electronic control of timing IMHO gives the majority of the economy gains compared to carby engines as the RV8 can take MUCH more advance at cruise. So maybe a Megajolt or just a Unichip to control timing is also a good idea.
This would also apply to carbies, and IMHO in your case with limited money, a pair of carbs, say 2inch SUs from a Jag ( or just the stock Strombergs) and a Megajolt controlling timing would be the cheapest and best system.
I don't agree with your idea of a "hot" cam as heavy trucks need torque. I would be looking at either stock say 3.9 Injected or a milder cam like a towing cam. Otherwise it will drive you mad as it falls off the cam on hills.
Really IMHO , the cam is the LAST thing you change. A few years ago there were several unhappy blokes on this forum who had bought "mild on road" cams and were very unhappy, and that was in a RRC/D1 .

Anyway that is my 10C worth. I have fitted a Thor manifold to a 14CUX and fitted Federal Injection to a 77 RRC so for more info , just PM me.
Regards Philip A

[101RRS]

Be aware that GEMS inlet manifolds are hardly different from D1/RRC 3.9 ones and have the fuel pressure regulator at the fuel rail. D1 may be easier to obtain. THOR systems have the fuel pressure regulator built into the pump assembly and a single line to the engine. You may have to fit your own external regulator to make it work on the truck. I believe you may be able to use the earlier injectors, rail and regulator in conjunction with the THOR manifold.

Just out of curiosity, are you putting gas back on this engine? Vapour injected gas would go well with your planned level of complexity.

I have a dead but complete 97 3.9 which still has its complete injection hardware still on it - I initially intended to use it but was advised it would not give any real advantages to moving my carbs from the 3.5 and having them rejetted.

I will not be mixing systems I just do not have that level of expertise - it will either be complete carby, complete Gems or complete thor with an aftermarket ECU.

After I get the truck up and running I will go back to LPG and if injected will be looking at LPG injection. If on carbies I will put vapour rings on the carbies as I have some and the relevant vapouriser.

Cheers

Garry

[101RRS]

Be aware that the Thor Motronic ECU is also tamper proof and has to be coded to the VIN.

The worst thing about a 14CUX is that it does not control timing. Electronic control of timing IMHO gives the majority of the economy gains compared to carby engines as the RV8 can take MUCH more advance at cruise. So maybe a Megajolt or just a Unichip to control timing is also a good idea.

I don't agree with your idea of a "hot" cam as heavy trucks need torque. I would be looking at either stock say 3.9 Injected or a milder cam like a towing cam. Otherwise it will drive you mad as it falls off the cam on hills.
Really IMHO , the cam is the LAST thing you change. A few years ago there were several unhappy blokes on this forum who had bought "mild on road" cams and were very unhappy, and that was in a RRC/D1 .

Thanks Phillip

You are correct about the ECUs and as my truck does not have most of the sensors that the standard ECUs need the ECU will be aftermarket.

I am looking at MegaJolt if I end up just needed an ECU to control spark. If I had my time again I would probably have gone a dissy timing cover as it gives more options.

The cam is not a "hot" cam as you indicated - it is a standard Crow Cams 4.6 High torque highway cam. Torque range is 1250 to 4100 RPM where a standard cam is 900 to 3750 rpm. As I said the 3.5 has enough torque lower down but not up high and even with this high torque highway cam the 4.6 will still produce far more torque than the 3.5 below 1250 rpm. I want more torque at 3500-4000rpm on the highway and the 4.6 combined with this cam should deliver that with no reduction at lower rev ranges.

I appreciate the comments.

Cheers

Garry

[101RRS]

Has anyone got suggestions on where to get standard lifters and a timing gear set. The Turners price on the lifters is about the same as I can get locally and the timing gear a bit less.

A local supplier known for good pricing would be good.

Thanks

Garry

[Pedro_The_Swift]

Maybe PM JC?

[101RRS]

I had decided to go the Thor route and use Megasquirt as that was the general consensus of opinion across a number of US and UK sites - I have since obtained the Thor gear in anticipation of the installation.

While the price listed on the Megaquirt V8 site for the Thor gear is high it did seem to be a complete package and suits what I need. HOWEVER - while it is listed on the site and you can buy some bits I found out today from the owner that development of Megasquirt for Thor is far from complete so that is really not an option at the moment.

Because of this THOR thing I proceeded on the process of not using a distributor and have a 4.6 Crow Cam that does not have the dissy drive. If I just want to use MegaJolt to drive the ignition that is about $800 and later I will be looking at the Thor Megasquirt when it is available but that would cost around $1800 so wasting the MegaJolt money.

So we are back to using Carbs or the 14CUX inlet/injectors off the 3.9 I have and the Bee Utey Holden Bosch modifed for early Rover use electronic dissy and electronic ignition system - has ran faultlessly for over 4 years.

So - some questions for the brains trust.

1. Will any 14CUX ECU run on any 14CUX engine or do I need a particular one - the manifold/injectors I have is off a 97 3.9 disco. Also will any 3.9 airflow meter work or do I need something particular. Will the 14CUx with airflow meter strangle the 4.6.

2. I can get the same grind Crow Cam as I currently have for the 4.6 (Hi Torque Highway Cam) in 3.5 engines from 1961-86 (I guess carby engines) so this has the drive for the dizzy where the one I have does not have a dissy drive. They no longer do a cam for 3.9 V8s. I have the 4.6 timing cover (now no use), a 3.9 timing cover (serpentine) and the 3.5 timing cover (V belt). Was looking at using a serpentine belt but I can just as easily go V belt.

So which timing cover should I be using on a 4.6 with a dizzy and what mods if any are required. I had bought a new single timing chain kit for the 4.6 but I might now be better getting the double chain kit for the engine.

I had another thread on aftermarket ECUs/Injection here Aftermarket Injection Systems - 4.6

Thanks

Garry

[bee utey]

I will say, IMHO, without exact knowledge of all the varieties of 14cux, that the best one to fit as a system is the pre '94 RRC one. The wiring harness is very much an independent thing needing only four wires from the vehicle wiring: battery positive, ignition positive, ignition coil negative and earth. It will run happily without any further inputs, eg road speed. Connect the EFI fuel pump wiring to the under dash plug or directly to the fuel pump relay at the ECU. I did exactly that to a 110 county with a carby 3.5 in it. My brother supplied a 3.9 vee belt RRC ECU and harness, the loom is nice and long as the ECU normally lives under the drivers seat. It even has a monster grommet to pass the wiring through any bulkhead without dismantling the ends of the harness.

As for the 3.9 hotwire system running a 4.6, I stuck a 4.6 into a '94 soft dash RRC and it performs quite well. The engines share the bore size so peak airflow isn't different enough to be a big problem.

[101RRS]

I will say, IMHO, without exact knowledge of all the varieties of 14cux, that the best one to fit as a system is the pre '94 RRC one. The wiring harness is very much an independent thing needing only four wires from the vehicle wiring: battery positive, ignition positive, ignition coil negative and earth.

Thanks for that - I believe the 14cux is basically the same until it was dropped.

Cheers

Garry

[101RRS]

As mentioned above for ignition I can go back to a dizzy system but I will have to get another cam and sell off the one I have.

The alternative is to still go without a dizzy but I will need and ignition ECU. The obvious is MegaJolt but its popularity seems to have forced prices up and they are now around $800 so not real cheap.

Does anyone know of another programmable ignition module that runs off a crankshaft sensor or something similar.

Thanks

Garry

[stuee]

As mentioned above for ignition I can go back to a dizzy system but I will have to get another cam and sell off the one I have.

The alternative is to still go without a dizzy but I will need and ignition ECU. The obvious is MegaJolt but its popularity seems to have forced prices up and they are now around $800 so not real cheap.

Does anyone know of another programmable ignition module that runs off a crankshaft sensor or something similar.

Thanks

Garry

Have you thought about running something like the Ford EDIS system? I gather this has been successfully adapted to rovers previously.

Ignition Control with MegaSquirt-II EFI controller
EDIS Ignition Control
Rover V8 trigger wheel kits