carbs to efi: which manifold?

**russotouristo** · 21st March 2014, 08:55 AM

thinking of this conversion... i got a block with engine no. startng with 26D. looking for inlet manifold, i've found one wih straight pipes and another one with bent 'sossiges'. will they both fit in place of my carb plate? (without drilling/welding). what's the difference between these two types? what engine types can become donors of inlet manifold in my case? what other mechanical components do i need for this project? (i got a fuel pump). fuel lines? upper chamber? throttle body? could anyone point me to some nice video describing the setup of the upper side of efi engine?

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**loanrangie** · 21st March 2014, 12:18 PM

If you are talking about an RRC or D1 then any inj manifold from 3.5/ 3.9 will fit, the thor 4ltr will also fit but work is required to setup .

**russotouristo** · 21st March 2014, 04:15 PM

exactly! what sort of work you are talking about?

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**russotouristo** · 21st March 2014, 04:16 PM

what about 4.6 or 4.7 from pegasus ?

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**loanrangie** · 21st March 2014, 08:10 PM

Originally Posted by russotouristo

what about 4.6 or 4.7 from pegasus ?

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Dont know what they are, do a search here for a thor to 3.9 conversion by PhillipA.

**russotouristo** · 22nd March 2014, 12:35 AM

thanks for the hint
as for 4.6 & 4.7 - I mean range rover P38A. probably GEMS (it's the name of engine control unit, the engine is still v8)

**loanrangie** · 22nd March 2014, 12:19 PM

Originally Posted by russotouristo

thanks for the hint
as for 4.6 & 4.7 - I mean range rover P38A. probably GEMS (it's the name of engine control unit, the engine is still v8)

Yeah i know what the 4.6 is but 4.7 or pegasus ? All rover V8 manifolds will interchange but you will need all the matching electronics or use an aftermarket ECU like Wolf, Motronic, or mega squirt.

**russotouristo** · 22nd March 2014, 04:47 PM

pegasus is the codename for p38a, isn't it? i've seen sale ads of 4,7l p38 - maybe just a mistake.
ecu is a different story - i'll try installing experimental versions of rusefi.
so mechanically-wise there shan't be any problems with bolting on the thor intake on the old engine previously equipped with a carb?

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**PhilipA** · 22nd March 2014, 09:30 PM

It is quite a job to get it running.
The only difference in the heads between carb and EFI , is that there is a little cutout in the port for the injector to get a straight spray.

It is not simple to fit a Thor, you would be better off with an injection manifold from a 3.9 RRC or D1.

1 there is no thermostat housing on a Thor manifold. You have to have one machined and use the 3.9 EFI thermostat housing.

2 you need a fuel rail from an early 3.9 RRC with the fuel pressure regulator on the Right hand side, and the fuel temperature sender at the front as later rails will not fit. ( you can fab up a rail of course but it is MUCH simpler and reliable to use stock components.

3 You have to grind the coil mounts off to fit the rail.

4 If you have an auto , the hardest bit is setting up a kickdown cable.

5 you need to get 19Lb injectors to fit the rail as Thor rail is one way and the injectors are short and run at a higher pressure.

This implies that you use the dizzy, as you have an old front on the engine if it is carby. A GEMS or Thor do not have a dizzy and the ECUs control timing. You can of course use direct ignoition by adding crank sensor and coils.
Regards Philip A

**russotouristo** · 22nd March 2014, 10:44 PM

thank you, Philip!
it looks like the easiest way is to find the normal intake with straight pipes!
but after all, what is the difference between these two? more torque at low rpm with thor? why so?

as you probably know, i've got a laser-cut trigger wheel to fit on the crank pulley, so ECU will manage both ignition and fueling. I'll be using two sets of ignition modules from 4-cyl cars (wasted spark), as they are not that expensive as individual coils ($40 per pack*2 vs $20 per coil on plug*8), plus they don't need drivers - they're controlled directly by 5v logic, which I'm not sure if it's true for these individual COPs.
however, I'd like to keep the dizzy for easy start (like North Star ignition), connecting wires directly to the ecu (when the corresponding circuit is closed, it's time to fire that cylinder)

Hope I'll cope at least with fitting the trigger wheel this summer

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