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Anyone converted a 3.9EFI to Carbs?

Posted: Tue Dec 23, 2003 9:15 pm
by RUFF
Just got offered a low K 3.9EFI but its had a hit in the front and the intake manifold is also missing parts. Im not interested in running the EFI.

I have all the parts from my 4.4 which is mainly 3.5 gear anyway including Carbs and manifold.

What i want to know is has anyone here fitted carbs to the EFI engine and still ran the EFI cam. How does it perform compared to a stock 3.5?

Posted: Wed Dec 24, 2003 7:13 am
by landy_man
there is a bloke on the aussie rover pages that has converted back to carbs... i have a feeling though that he stuck an edlebrock or rochester carby on....

try here http://members.boardhost.com/blumx/

Posted: Wed Dec 24, 2003 7:16 am
by Bodge
Yep - a friend is running standard 3.9 with rejetted SU's from a 3.5. Definitely out performs the 3.5 and runs well on angles...

If you want detail I can give you his eMail - good guy will be happy to answer questions.

Posted: Wed Dec 24, 2003 3:27 pm
by RUFF
Thanks guys i bought it anyway. I will know hopefully before New year how it goes.

Posted: Thu Dec 25, 2003 6:34 pm
by amtravic1
I converted from efi to carby. Let me know if you need more info.
Ian

Posted: Thu Dec 25, 2003 9:23 pm
by RUFF
Ian are you still running the EFI cam shaft? Is the Fuel economy any better than a Carb 3.5? Have you had any problems at all due to removing the EFI?

Posted: Thu Dec 25, 2003 9:47 pm
by Rainbow Warrior
I plonked a brand new 3.9 short motor into my 76 Mangey using the 76 heads, timing covers, manifold & carbies, it was magic, sweet at 6000prm and plenty of grunt at idle, angles worked fine.
I used the 3.9 factory cam, had my heads rebuilt and fitted Lumitron electronic ignition.

Posted: Fri Dec 26, 2003 7:34 am
by amtravic1
Tony,
I used an edelbrock manifold with a a square to speadbore adaptor and a quadrajet carby with a Holden V8 airfilter. I use the same cam and disributor. At first I used the efi pump with fuel return and a pressure regulator but recently changed fuel tanks sto I took the oppurtunity to remove the efi pump and fit a low pressure pump outside the tank. Its all easy work and took less than a day after I assembled most of the parts. I used a Speco Holden V8 throttle cable and soldered the nipple on the accelerator end from the Rover cable as the original cable was just to short.
I found that I have more power, better economy, more reliability than with the efi and the motor is far less cluttered. The only thing is the height of the carby and adaptor with the Holden airfilter just fits in the height available. A square bore carby with no adaptor needed would give more room for airflter options but my setup works well.
Ian

Posted: Fri Dec 26, 2003 5:10 pm
by amtravic1
Tony,
I almost forgot, had to rewire the fuel pump as there was something in the efi setup that told the fuel pump to run for more than a few seconds after startup. Found out later there was something in the airflow meter that switched the fuel pump on when there was enough airflow. No mater as I completely removed the efi wiring anyway. Sorting out why the fuel pump would not keep running then rewiring it took more time than all the rest of the work.
Ian

Posted: Fri Dec 26, 2003 10:27 pm
by RUFF
Thanks Ian.
Dont know if you realised but this is actually fitted to a Hilux.

I swapped all the accessories over from my 4.4 to the 3.9 today so it should be back in and hopefully running again tomorrow.

Im using 175CD strombergs and a modified Disco Electronic Dizzy.


I also sripped the 4.4 down and cant find why it was rattling. All the bearings are fine and although i havent removed the pistons yet they look fine and all the sleaves apear to be located right.