7747 to 7247 conversion, need info!

[89S10_Project]

Folks-

I tried the search. but didn't find much.

I've been a bit overwhelmed by all the information here and elsewhere about EFI. One thing I keep running into is suggestions to upgrade my present ECU (1227747) to a 7247 (I believe 16197247 is the one?) ECU.

Truck is an 89 S10 Blazer, 4X4, SOA/SAS, Dana 44s (4.10, regearing to 4.56 soon)smallblock 5.7L V8, 700R4 and NP231C.

The engine is in a mild state of tune, I pulled it out of a junkyard so don't know much more about it than that it was a GenII 94 crate motor put into a 89 C1500. All evidence (borescope of the cylinders, vacuum, oil pressure, cleanliness of innards) points to it having been junked shortly after being installed. I got LUCKY!

What, specifically, is better about the 7247? I understand I'll have to depin/repin the connector- that's child's play, I can do that in my sleep (I used to build Canon plugs on Navy vessels.. If I can build the cabled for an AN/UYK-20, this ain't nothin'!)

I understand that I'd stil have to have a supply of chips to burn new BINs to. I also see that there is a "flash-upgradeable" board available for the 7747 and the 7247. In my line of work that means you upload a new program over a console cable and you're done- is that true here as well?

Seems the major issue with the 7747 is that it's slow. Well, it's not running a moon shot, why does that matter? Is it simply to get better, more granular log data and to run more precise metering?

I can pull a 7247 out of a yard, get connectors and pins off Ebay (though feel free to recommend other sources), and then get to it. Obviously I'd need special connector crimpers- I don't imagine folks are paying for $400 connector pliers- what does the educated and accomplished DIY EFI guy do for a good connection? The first thing that comes to my mind is carefully folding the terminal prongs over as compact as possible and then silver-soldering the pin on very carefully, with just enough solder and no more. Again, cake- though I'll DEFINITELY need my glasses and some magnification on the job..... :)

Speaking of connectivity, anyone got a runsheet for the pinout swap? Or failing that, a diagram for the 7247 (I have the 7747 already)

7247 is still OBD1. Why bother??

I've also considered going Megasquirt, but due to some good advice I think I will stick with GM units.

Also, on the chance I actually carry through with a blower- can the 7247 handle a blower into a TBI unit? I'm probably going to be advised to go with a 7749 (is that correct, the Sy/Ty ECM?)

[jim_in_dorris]

Repining to the 727 ecm is as simple as pushing the pins out of the old connector and pushing them into the new connector. Just get the 2 connectors when you get the ecm from the jy. Tuning wise, you get much better data rates, making granularity better. This makes tuning easier. The $0D code is also better. There are some threads around which contain the pinouts, fast did a nice writeup about it, I just don't have the link off the top of my head right now. I have done it, it isn't hard.

[89S10_Project]

Is there a tool used for the pin removal? I know an xacto knife can be used for this sort of thing, but also know these pins can be fragile- it's always best to use the actual pin removal tool.

[Chewy1576]

Is there a tool used for the pin removal? I know an xacto knife can be used for this sort of thing, but also know these pins can be fragile- it's always best to use the actual pin removal tool.

I used a paper clip.

[89S10_Project]

Note to self, and hoping to help someone that might come across the same issue:

From the FAQ- everything I need to convert from 7747 to 7427:

http://www.gearhead-efi.com/Fuel-Inj...out-Directions!

[Chewy1576]

Note to self, and hoping to help someone that might come across the same issue:

From the FAQ- everything I need to convert from 7747 to 7427:

http://www.gearhead-efi.com/Fuel-Inj...out-Directions!

I used the same pin out list when I converted 1228747 to 16197427. Everything was spot on.

[89S10_Project]

I used the same pin out list when I converted 1228747 to 16197427. Everything was spot on.

Thanks, figured it would be, they keep things pretty accurate around here.

What prompted you to go to the 7427? Did you pick up any mileage with the new injection system?

[dave w]

Maybe this is an option for your conversion? http://www.gearhead-efi.com/Fuel-Inj...s-135-Shipping

dave w

[89S10_Project]

Maybe this is an option for your conversion? http://www.gearhead-efi.com/Fuel-Inj...s-135-Shipping

dave w

It would be for people that don't have the skills I do. It's certainly an option.

However in my career I learned long ago to solder well, so as long as I can score the parts I can make it myself in an hour or two while watching television.

In fact I will most likely just repin and be done with it.

[Chewy1576]

Thanks, figured it would be, they keep things pretty accurate around here.

What prompted you to go to the 7427? Did you pick up any mileage with the new injection system?

I wanted the '7427 for better tuneability after replacing the old, tired 350 with a 383 crate engine and the option for 4L80E control later if I get tired of the NV4500.

[89S10_Project]

Much the same as me, then. I've got the S10 I've shoehorned a 350 into. I was having fueling troubles but rebuilding the FPR and putting new injectors in have solved that. I still have the V6-spec 700R4, and am looking into either replacing the trans with a 4L60E or 4L80E, or a built 700R4. Not sure which way I'm going- I'd like to be able to just swap to a 7427, throw a 80E in and be done, but things never go that easily...

First concerns are, will my NP231C even bolt up to a 4L80E?

[Chewy1576]

Much the same as me, then. I've got the S10 I've shoehorned a 350 into. I was having fueling troubles but rebuilding the FPR and putting new injectors in have solved that. I still have the V6-spec 700R4, and am looking into either replacing the trans with a 4L60E or 4L80E, or a built 700R4. Not sure which way I'm going- I'd like to be able to just swap to a 7427, throw a 80E in and be done, but things never go that easily...

First concerns are, will my NP231C even bolt up to a 4L80E?

I believe the '7427 can only electronically control a 4L80E. The 4L60E would need a different PCM, but I can't recall which one specifically. You can also configure a '7427 to run a 700R4.

[89S10_Project]

I believe the '7427 can only electronically control a 4L80E. The 4L60E would need a different PCM, but I can't recall which one specifically. You can also configure a '7427 to run a 700R4.

Sorry, that's my dyslexia getting the best of me. Meant a '7247....

[halljam70]

The 7427 will control the 4L60E too. The reason I swapped from the 7747 to the 7427 was to run a MAF sensor. Runs so much better than Speed Density.