EFI on '72 Mach 1

Stanger007 · Dec 31, 2007

I'm itching for a new project and would like to convert my '72 over to EFI. There was a guy on here that I PM'd with that had it done and I lost his screenname.

I'm looking for some install pics and any words of advice and "gotchas" involved.

I think the A9L computer is going to be my best bet due to it's popularity. It looks like the going rate for these things are around $150, does anyone have a good source for getting a complete harness and computer?

I've got an intake, MAF, IAC, TPS, ECT, IAC, injectors, throttlebody, intake tubing, O2s, coil and misc sensors from my '95 I will be using.

I will need a distributor and TFI, are they a drop-in to the older 302 blocks?

What do I need to do for the return fuel system and pump?

Will there be any issue with the VSS? I'm running a C4.

The tuning/EGR etc is not a problem for me, I do quite a bit of tuning on the 94/95 model Mustangs and have a chip burner etc.

Thanks,
Wes

reenmachine · Dec 31, 2007

There are always A9L computers on eBay for cheap. Email me if you're interested in a new harness -- I've got great plug-and-play ones.

Stanger007 · Dec 31, 2007

Thanks for the response. Your harness looks amazing, nice work. I bet a lot of TLC goes into making those bad boys.

After doing a lot more reading, the swap looks very straight forward, the wiring and fuel system being the most labor intensive parts.

I'm trying to figure out if I can keep my cam's firing order and modify a table in the PCM to accommodate the old firing order or if I need to find a non-roller cam with the new firing order. Switching distributor gears on a Mustang dizzy or just buying a distributor from a later model (non-roller) F150 is not an issue.

Lot of little details but so far it looks good, having tuned these PCMs quite a bit has helped in understanding what needs to be modified.

I'd love to see the wiring/mounting pictures if anyone has a PCM in their glovebox. reenmachine, where do you put your PCMs at?

Wes

reenmachine · Dec 31, 2007

I usually mount them above the driver's side kick panel. I don't know what's there on a 71-3 off the top of my head though. On a 67-8 I eliminate the fresh air vent over there to make room for other stuff so there's lots of room.

RMODEL65 · Jan 1, 2008

good page for efi conversion info http://www.midnightdsigns.com/james/

reenmachine · Jan 1, 2008

Stanger007 said:
Will there be any issue with the VSS? I'm running a C4.

Thanks,
Wes

Forgot to address this part...

The VSS input is pretty important on an automatic car. You can get a factory sending unit that has both the 2-pin connector for the ECU and a cable pass-through for your speedo that'll plug right into your C4. I'll have them here soon and I'm sure you can find them with a Google search.

Stanger007 · Jan 1, 2008

Thanks again for all the help and advice.

I've got a lead on a harness and PCM. Furiously researching and planning the rest of the swap. I'll post up pics and a writeup as it progresses.

Wes

66Runt · Jan 1, 2008

Best to use cam with H.O. firing order. A9L is not quite that versatile. Besides you *really want* a new cam to take advantage of the EFI anyways.

Have fun!

View attachment 339097

Stanger007 · Jan 2, 2008

Haha funny picture.

There is a table in A9L that dictates firing order, I will burn a chip with that changed to get it back right. If that does not jive with the adaptive strategy for some reason, I'll swap in a HO firing order cam and call it a day.

I'll swap in a roller block down the road, but this engine/tranny is so fresh that it seems a waste to do it now. The '72 is my fun/cruiser car... the '95 is the one that gets beat on at the dragstrip.

Wes

65ShelbyClone · Jan 2, 2008

The bottom of the TFI distributor shaft is slightly longer than the others, so be sure to check that for compatibility if you upgrade the oil pump shaft to an ARP. I put one in an '89 GT and had to shorten one end by about 3/16 to 1/4". I don't recall exactly, but FMS/FRPP either has two different pump shafts or one that fits both applications. Don't forget that a roller cam TFI distributor will have a steel gear which isn't compatible with a slider cam.

You shouldn't have any trouble finding a slider cam with the 351W/5.0 HO firing order if you choose.

bnickel · Jan 2, 2008

IIRC you can change the injector firing order by rewiring the injectors to the correct order, the computer doen't know the difference that way. it's been a while since i read that but i'm pretty sure it can be done.

alternatively, i think you might be able to use the injector harness from a non H.O. 5.0 like from a crown vic or towncar

65ShelbyClone · Jan 2, 2008

I was just reading that it's not a good idea to do that because it throws off the ECU when it's doing O2 calculations. Something about the ECU doing corrections based on the injectors and O2 sensor assigned to a certain cylinder bank, but that gets thrown off when the injector plugs are rearranged.

bnickel · Jan 2, 2008

65ShelbyClone said:
I was just reading that it's not a good idea to do that because it throws off the ECU when it's doing O2 calculations. Something about the ECU doing corrections based on the injectors and O2 sensor assigned to a certain cylinder bank, but that gets thrown off when the injector plugs are rearranged.

hmmm, that's a new one on me but like i said it's been a while since i read about doing that. although i'm not sure how it would throw off the O2 sensor calculation, since it measures the amount of available oxygen in the exhaust, as long as the engine isn't running rich or lean it really shouldn't effect that.

Stanger007 · Jan 2, 2008

I'd agree that rewiring the injectors will throw the adaptive strategy (learning fuel trims) off. The PCM looks for exhaust pulses based off of when it thinks an injector fires.

Thanks for the tip on the distributors being different. I do have an ARP shaft in the motor already. I will measure my dizzy against one from the mid 90s F150 (non-roller 5.0 w/ TFI) to make sure all is well there.

Wes

EFI on '72 Mach 1

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