I need help selecting the "best" ECU for my car. It's a 1971 Chevelle convertible. I have a TPI manifold setup from an '85 Z. Should work great with my tall gears.

I have decided to go with a GM SD ECU and learn to tune it. I know the 730 was used for SD TPI cars, but is that the best one for me to use? I do not have the harness or sensors yet. Would an LT1 ECU be better, since I would save on the chip burner? What's the pro's and con's of each?

Thanks
Mike

 

Forgot to mention specs:
350 SBC from '76 truck (4 bolt)
'70's smog heads
Mild cam - Pulls 15" at 750rpm idle
TH350
2.7 rear
(Don't know about compression or cam spec, I did not build it)

Mike

 

The 730 is cheap, readily available, and you can make the wiring harness from just about any V6 car instead of having to pay out the nose for a custom made harness or waiting to find one from a thirdgen car. A LT1 ecm can work but you would have to make the dist an opti sensor. Not too hard to do, just have to graft the opti to the dist. Thing is price and availability. ECM is no problem but getting a used opti would be hard and buying a new one with no core is, well, expensive. And to be honest you can pull a prom, burn it, and reinstall it faster than you can flash a LT1 pcm. I know, I have both. But you can also spend a little extra and burn on-the-fly on the 730 which would be faster yet. Your best bet (while it may not be the best ECM) is a 730, just one opinion though.

 

You mean I can convert a V6 harness to V8? Do I just have to add 2 injector wires? Is there instructions somewhere on the net?

This would be great, because the harness is the most expensive part.

I don't want to mess with an opti, so I guess it's a 730

Thanks
Mike

 

Well there are no sites that I know of that have that info but I can tell you what I did. First you will need a harness from a V6 car. The choices are few but the cars are plentyful in U-pick junkyards. Camaro V6 with the 730 ecm is an obvious first choice but that was only 90-92 cars. Then come the FWD V6 cars like Beretta and Corsica. These cars came with a 730 from 86 or 87 to 91 or 92. Get the whole harness, especially the outside wires!! You will have to go by the passenger side and undo the weatherproofing at the firewall. This will most likely be the biggest hassle. The inside wiring is not as crucial except of course the mass of wires that go to the ecm from inside to outside. The wires that go from inside to inside you can just cut long as you'll have to add length to those anyhow. The wires outside will be extra long except for the MAP and injector wires so you'll have some cutting and splicing to do. And of course you'll have to add two injector connectors but not a big deal as there are only two wires coming out of the ecm for the injectors and the factory splices them anyhow. You'll also need ignition connectors for the dist. as these cars are DIS so get those from a truck or other V8 application and might as well grab the dist. too. The small cap ones are nice (external coil) and are generally just newer. If you can't find those connectors for some reason, IAC and CTS ones will work I believe but the colors will be wrong. Which is OK because the colors will be wrong on a few items as you look at the wiring diagram from the V6 donor car and the V8 application you plan to run. This is critical to keeping track of what is what so you must get a good diagram of both and remeber to get the year of the donor car. The ignition wires and certain sensors (tps, cts) will be the same but I found the MAP and other things to differ. Also, you may have to add a wire (VATS) and get rid of others (EGR, AC) from the ECM connectors. This is really easy to do with a real small pick or eyeglass screwdriver set.

One other option, especially if you are pressed for space inside the car, is to run the 727 ecm. This comes in Luminas and other W bodies (Regal, Cutlass, etc, also found on 90-91 vettes) from around the same years. It is the same 730 ecm but it is mounted outside in the engine compartment, between the water pump and the fuse box. It looks different and has different connectors but does the exact same functions. My boss has one in his 87 Ram 250 controlling a 96 360 Magnum engine. I guess it would be easier to pick the harness from that too.

Good luck and trust me the effort is worth it.

 

Hectorsn,

Thanks for the Info. I went to the junkyard Saturday and got the ECU and harness from a V6 Celebrity. Was harder than I expected getting all the wires. There were lots of the 727 available also, But I was afraid the memcals might not be a perfect match, and there seems to be more info around on the 730s.

This is going to take some doing sorting out the wires. I suspect I only need about 1/2 of the wires in the harness.

Thanks again