Converting a '74 Carb'd Manta to Fuel Injection

[ohiocymru]

Bought a fuel injected '75 Manta parts car that doesn't run due someone stripping the water pump and radiator from it for a GT project. Anyway, I have a '74 Manta that's carb'd and want to convert it to a fuel injected engine. Is it a fairly simple swap or are there some major problems involved? I don't know how long the car hasn't been running, and I don't know if there are any major engine issues, but I'm debating on buying a spare water pump and radiator to see if it will run. If it does, then I will most likely do a engine swap. Any info would be great.

[Gordy]

If you just need to see if it will start or run I would not even worry about a radiator or water pump. If it fires up you only need to let it run for a very short time to listen for knocks etc. Are you planning to put the engine from the 75 into your 74 or are you just installing the efi from the 75 onto your 74's engine?
If you're just using the efi onto your existing engine, you will need the electronic control unit from behind the right kick panel, the electric fuel pump off the 75, and you may need to add a fuel return line to the tank (not sure but I doubt a fuel carbed 74 model would have that unless there is an emissions line running back to the tank).
Every component to the Bosch fuel injection is available new except the ecu and the saddles that the injectors sit into. Those should both be available used.
Also the valve cover off of the 75 has the throttle cable bracket which the carbed valve cover does not. You would also need to switch to the 75 thermostat housing and get the proper lower radiator hose plus the connector hose for the 75. You'll need to add the wire to the ecu from the coil and of course the wire from the dual relay on the right fender well back to the fuel pump.
I'm interested in the progress you make and any problems you might encounter. Keep us posted.

[jlthunder]

Just a note on the water pump on the '75. The '75 used a fan clutch on the waterpump. The bolt which connects the clutch is a left handed thread. Righty tighty, lefy loosie does't apply. It is the opposite. The bolts which connect to the timing case are normal. Since the water pump assembly is missing from the '75, you can use the complete assembly, including the fan from the '74 assembly.

The purpose of the fan clutch is to save some horsepower so the engine doesn't have to spin the fan at full speed. Just some FYI.

[ohiocymru]

you will need the electric fuel pump off the 75, and you may need to add a fuel return line to the tank (not sure but I doubt a fuel carbed 74 model would have that unless there is an emissions line running back to the tank).

Somebody before me has already added a electronic fuel pump which is also why i need to buy a block off plate for the manual fuel pump. As far as the return line I'm not sure, but i thought the line that loops through the right side in the trunk is a return line that Ts back into the tank. Had to replace that one and just about all the other lines back by the tank due to some serious porosity. I want to use the EFI from the '75 on the '74 engine because I know how well it runs. If the '75 ends up running without any issues I might just do an engine swap and then rebuild my '74 in order to beef it up for a Garrett Turbo. Once its finished I'll transplant it back in and swap the fuel injection back over. Of course If I can get it all new except for the ECU I might just buy a second EFI system for the rebuilt '74. Lots of variables there but somehow it will all work out. Thank you for all the info that you've given me and ill be sure to keep everyone posted on my progress or there lack of which ever it may be lol.

[ohiocymru]

Just a note on the water pump on the '75. The '75 used a fan clutch on the waterpump. The bolt which connects the clutch is a left handed thread. Righty tighty, lefy loosie does't apply. It is the opposite. The bolts which connect to the timing case are normal. Since the water pump assembly is missing from the '75, you can use the complete assembly, including the fan from the '74 assembly.

The purpose of the fan clutch is to save some horsepower so the engine doesn't have to spin the fan at full speed. Just some FYI.

I would love to find a fan clutch for my engine, but I've also thought about running electric cooling fans to reduce the amount of horsepower robbed from the fan. I was lucky enough for my wife to find two Opel Mantas in this state not so sure I'll be as lucky as to find another water pump with a fan clutch assembly lol. Thank you for the info.

[Gordy]

Is the electric pump on the 74 now? The 75 efi needs a pump that will deliver about 45 (I think 44 pounds is minimum) pounds of pressure where most pumps for carbed engines are between 4-7 pounds I think. You'll want to check that out. If you go to the Bosch web site and check by part # because they won't have Opel show as a search option, you can find most items. AutoHaus in Arizona had real good deals on the injectors and dual relay. Some sensors Rock Auto still had available and maybe the cold start injector as well.
The return line on the efi set up returns fuel from the fuel pressure regulator that isn't sent to the injectors back to the tank rather than building up pressure. On the main fuel line you will need high pressure fuel injection hose and clamps. The return line is not under pressure so regular line might work there.
You will see on the 1975 that the 2 fuel lines come out on the right side near the rear of the inner front wheel well. They are aluminum or stainless steel lines.
You could post some pics of the efi system and we might be able to see how complete it looks.

[ohiocymru]

I'll look into the type of fuel pump that is installed on my 74. If you look at my OpelZwei album there should be a few pics of the fuel system. I'll try to take some more specific pictures this coming weekend.

[tekenaar]

. . . you want to know about converting '68-'74 Opel CIH-powered models to Opel Bosch L/LE-Jetronic FI

[ohiocymru]

. . . you want to know about converting '68-'74 Opel CIH-powered models to Opel Bosch L/LE-Jetronic FI

This looks awesome. Looks to be fairly idiot proof as well which is exactly what I need lol. Thank you Otto.

[tekenaar]

. . . you want to know about converting '68-'74 Opel CIH-powered models to Opel Bosch L/LE-Jetronic FI

This looks awesome. Looks to be fairly idiot proof as well which is exactly what I need lol. Thank you Otto.

. . . pics and text about installation in a GT, but this generally applies to other models as well.



. . . note that these pics are scanned Polaroid photos, LOOONG before the 'digital-everything' age. These are of my first GT ('73) to FI/Perlux(now Pertronix) conversion back in '78!



. . . note that P/N is still the same!