GM 305 conversion to TBI

[framkiss1]

I am in the process of collecting all the necessary parts I would need to Convert my Chevy 305 motor to TBI. So far I have the following items from a donor vehicle which I picked from the salvage yard. All of the parts came from a GM 350 motor 1989 I believe. I could not remove the intake because four(4) of the bolts snapped off so I have to look for another one.
ECM ( I lost the tag with the ECM number)
Complete Electrical Harness. (I hope I cut it correctly) I will post a picture for comments
TBI Unit
Distributor and Coil
I am awaiting the following:
Original TBI intake Manifold. (Reason being is that when I install this engine in a Jaguar XJ6 I would not have any room for hood clearance if I were to use an aftermarket manifold which may require an adapter for the TBI unit. Am I wrong in thinking this way?)
I will be purchasing the TPS,MAP sensor,CTS, inline fuel pump, O2 sensor and a Knock sensor. Am I missing anything? I may want to eliminate the EGR system for simplicity sake. Am I wrong in my way of thinking?
Any and all input will be greatly appreciated.

[1project2many]

Hello, and welcome to gearhead-efi.

This sounds like an interesting project. I think you're on the right track with finding a donor vehicle although. The 350 calibration will not be right for the 305 so you'll need to change that. If you want to use a stock calibration then you'll also need 305 injectors. We can usually identify the ecm part number if you can get the three or four letter code off the computer chip inside. You're probably right in thinking a 4 barrel manifold with an adapter may take up too much space under the hood. If you obtain an intake manifold from a 1991 style Caprice it will provide increase hood clearance although you'll also need the distributor as it has a larger base than the truck distributor. Make sure your knock sensor is for the 305. The rest of the sensors should be the same for both the truck and car engines.

[framkiss1]

Thank you. I can find a 305 TBI unit and intake manifold. If that fails can I purchase 305 injectors and install them on the 350 TB?

[1project2many]

Yes, 305 injectors will replace the 350 injectors.

[framkiss1]

So, I am in the process of weaning the electrical harness of the circuits I would not need, but I need some help. I have identified and checked the circuitry from the ECM connectors to the following basic components: FUEL PUMP RELAY AND WIRES TO PUMP;EGR SOLENOID;TPS;MAP;IAC;02 SENSOR;CTS;ECT;FUEL INJECTORS;POS WIRE TO COIL
There are a few connectors which I cannot identify so I don't know if I need them. See pictures below. What do I need and what don't i need are the questions. Also, I cut the eight(8) wires going to the ALDL connector (about 14 inches)Where will I be connecting these wires?
I guess someone who has done this before can chime in.
Thanks

[fastacton]

In photo 3, the larger connector is the ESC (knock filter) and the smaller one is for the smog pump. The connector in the 4th photo looks like the ABS connector, you can just delete it.

[framkiss1]

I pretty much have the donor harness sorted out. Thanks for the info regarding the ESC. My main concern is the ALDL connector. My has eight wires and I am trying to figure which ones I need to connect. I will post a pic of my ALDL connector in my next post.

[damanx]

Someone who knows better than I could probably answer without further info, but I would need to know what ECM you are using.

[1project2many]

A minimal installation has three wires: A, B, and the data line. Low speed data such as the old TBI systems like yours had an orange data line on pin E. High speed data systems such as the later 94-95 TBI placed a high speed data line on pin M. I would make sure I placed a data line in both locations in case I wanted to change to a later ecm with high speed data.

I don't usually use anything more than the minimum on my swaps. You can decide what other lines you'd like to delete based on what's already in your harness, whether it's easier to include or delete a particular circuit, and what you feel might be helpful for diagnostics down the road.


https://www.obd-codes.com/faq/gm-aldl-connector.gif