'80 Corvette 350 4 spd M/T, '93 TBI, '94 454 TB, 7427 PCM

[rdicarlo]

Hi All,

Long time lurker, first time poster.

I've had my "project" '80 vette for almost 20 years, since I was 19. Here's what's in it now:

Block GM 3970010
Heads GM 462624 on it now; Edelbrock Performer RPM 64cc 608919 will go on soon
Cam/Lifters Crane Cam/Lifter kit 100172 (I'm not sure why I put in a circle track cam, but it actually idles pretty good)
Intake Manifold Edelbrock 7101
Edelbrock 600 Carb

The carb and intake have been on the car for over 5 years, but they have less than 100 miles on them. Now I want to convert to EFI. I've been tinkering with my '87 vette lately and fell in love with the concept of fuel injection and closed loop engine management. The car's TPI system is finally running good and the car rocks. I used Datamaster and TunerCAT to datalog and burn chips with a Moates AutoProm. Bought a tune from Scott Hansen and he retuned based on my datalog until the car ran good. Good guy. He only does TPIs and it won't fit under my '80 hood. So I'm going to try to install and tune my first TBI system...

So far I've accumulated the following for the TBI conversion but none of it is installed
New '82 Corvette Fuel sending unit (it has provisions for a fuel pump)
New Walbro 255 lph pump
'7427 PCM from a '93 4.3L
Full PCM to engine bay harness from a '93 4.3L
All the sensors and modules on the harness. I think there is some emission stuff on there that I'll strip out when I clean up the harness
'94 454 trottle body with stock injectors. Can I use the stock 454 injectors if I turn down the fuel pressure?
TBI to carb intake adapter plate

I think I'm going to get a new distributor next, but need to do some reading on which one first.

BTW, thanks for posting all this great info on GM EFI systems. It's an interesting hobby that's fun because people like you folks.

Rob

[rdicarlo]

I'll follow the swap with pics in here. Starting on the harness soon, so I'll write it up.
Can someone confirm that I can use a Moates G1 adapter to host a 27SF512 chip in the 16197427 PCM from a 93 4.3L? That's what I do on my '165 TPI ECM.
Thanks

[dud]

I'll follow the swap with pics in here. Starting on the harness soon, so I'll write it up.
Can someone confirm that I can use a Moates G1 adapter to host a 27SF512 chip in the 16197427 PCM from a 93 4.3L? That's what I do on my '165 TPI ECM.
Thanks

Yes. This is the same combination that I use with the "8625" pcm which is essentially the same pcm.
Here is a great resource for all the tuning files you need for the "7427". "http://www.gearhead-efi.com/Fuel-Injection/showthread.php?303-16197427-PCM-Information-0D"

Caution, you may need to get a knock sensor specific to a 93-95 V8 engine. I'm pretty sure I've read here that V6 knock sensors don't work well in a V8.

Good Luck. Look forward to following your write up.

Dud.

[rdicarlo]

Thanks for the reply Dud. I have been doing some research. I see some 16197427 PCM to sensor and TB info for years up to 90 and 94-95. Is there any reason 91-93 is left out? I have pretty much a junkyard pull TBI from a 93 4.3L. I may need a new knock sensor and wire adapter for the 94 454 IAC to 93 IAC 350 wiring. I need to also find a V8 memcal.

[rdicarlo]

I'm going to try to not run a knock sensor. My buddy said the cam will drive it crazy.

Does anyone know if its possible to run the 7427 on a manual transmission 350 without the knock sensor? Sorry, I'm fairly new at this stuff.

Thanks,
Rob

[rdicarlo]

I want to use the MSD Street Fire HEI Distributors 8362 distributor and leave the wires for electronic timing control for future upgrades.
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If possible, I would like to use the 7427 to lny control the fuel right now. I don't need the auto trans options either because I have a manual transmission.

[rdicarlo]

I'm going to try to not run a knock sensor. My buddy said the cam will drive it crazy.

Does anyone know if its possible to run the 7427 on a manual transmission 350 without the knock sensor? Sorry, I'm fairly new at this stuff.

Thanks,
Rob

Well after much reading, I'm starting to think that it makes the most sense for me to buy a 1227747 ECM and ECM connectors. Just repin my 7427 harness to it. Considering that I'm running a manual transmission and not using the advanced timing features of the 7427, it doesn't make a lot of sense for me to struggle through trying to get the it to work.

[fastacton]

If you plan on going with timing control in the future, you might want to stick with the '7427. It can be made to work as a fuel only setup and you don't have to solder in a G2 adapter to use a flash chip, just get a G1 and ZIF.

[rdicarlo]

If you plan on going with timing control in the future, you might want to stick with the '7427. It can be made to work as a fuel only setup and you don't have to solder in a G2 adapter to use a flash chip, just get a G1 and ZIF.

Hi fastaction, thanks for chiming in.

So it doesn't matter that my transmission doesn't have vss? At least I don't think it does. Its a super t-10 4 speed.

As long as someone who knows more about this stuff than I do says it can work then I'll stick with it. TY

[rdicarlo]

I have a memcal for a 4.3L now in the 7427. I'm not going to be using the VSS or Knock sensor. What is the best memcal for a 5.7 with a manual transmission? I think I need to buy one for a V8, but I have no clue which one to choose. Please help. Thanks, Rob

[1project2many]

First, I have to ask, why won't the TPI fit under the hood of the '80? I happen to know someone who helped with this exact swap. Even the internet thinks it can be done: http://www.c3vr.com/vrforums/will-tuned-port-injection-fit_message140188.html

Are you going to skip all timing controls or just the knock sensor? Even without knock detection you have plenty to gain by switching to computer controlled spark. You could even leave the carburetor intact and you'd still see improvements.

The correct memcal for the ecm will match the engine regardless of transmission type. A 5.7 engine should have a 5.7 memcal. Folks often use the 5.0 memcal but you want to avoid the V6 version.

I would recommend using the 7427 ecm. It has more features and more code to do a better job of controlling the engine. The calibration settings can be changed so the 7427 ecm does not panic because you have a manual transmission. I would strongly recommend doing the work to install the VSS now. The ecm really does rely heavily on a speed signal. You can buy a simple sensor that can be installed inline with the speedometer cable.

I would probably avoid buying a new distributor if the old one is still ok. I see a lot of parts made overseas that don't seem to have the same quality and lifespan as older US made parts.

[rdicarlo]

First, I have to ask, why won't the TPI fit under the hood of the '80? I happen to know someone who helped with this exact swap. Even the internet thinks it can be done: http://www.c3vr.com/vrforums/will-tuned-port-injection-fit_message140188.html

Are you going to skip all timing controls or just the knock sensor? Even without knock detection you have plenty to gain by switching to computer controlled spark. You could even leave the carburetor intact and you'd still see improvements.

The correct memcal for the ecm will match the engine regardless of transmission type. A 5.7 engine should have a 5.7 memcal. Folks often use the 5.0 memcal but you want to avoid the V6 version.

I would recommend using the 7427 ecm. It has more features and more code to do a better job of controlling the engine. The calibration settings can be changed so the 7427 ecm does not panic because you have a manual transmission. I would strongly recommend dong the work to install the VSS now. The ecm really does rely heavily on a speed signal. You can buy a simple sensor that can be installed inline with the speedometer cable.

I would probably avoid buying a new distributor if the old one is still ok. I see a lot of parts made overseas that don't seem to have the same quality and lifespan as older US made parts.

Hi,

Thanks for the reply.

The hood has a molded hood scoop that decreases the clearance under the hood. I've run into issues fitting some air cleaners under there.
10412

But TPI may fit; I didn't measured it. The main reason for not going TPI is that my 87 vette has it. I'm in this to learn. That's the fun part for me. I want something a little different to tinker with on my 80 vette and the GM TBI seems like a great DIY project.

In regards to what the rest of my plans are, I'll do as much as I can with the support of this forum. So, I've been told that I can't run a knock sensor because of my cam. I'll follow your advice and try to setup the timing as well as fuel.

I'll stick with the 7427 and get a 5.7 memcal. I was reading that I could buy a JTR 2PRS VSS that will install inline on the speedo cable for $97. I'll check if there's room to install it on the Super t10 trans or behind the cluster. Unfortunately, all I have now is a vacuum controlled HEI distributor and i think I would need to buy a new one if I want to control timing.

Thanks again for all the help.

Rob

[rdicarlo]

Before
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After
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I started working on the wire loom. I separated the trans wires/connector out of it. I'm sure I can take more wires off, I just don't know which ones yet.

[rdicarlo]

I worked on the harness a little more. I'll have to finish it up on the car. I may have the negative routed incorrectly, but I'll fix it on the car.
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[rdicarlo]

I'm going to continue this mod write up over at the corvette forum. Thank you to those who took the time to reply. Rob

[Aceman]

I did a tbi 625 ecm swap on my 79 vette a few months ago. It has a thm350 trans right now till i install the 4l60e . Runs good. I did fuel and timing with the trans harness tied to the side for now. Pretty much a stock motor, gm rebuild installed by previous owner. 93 pickup was the doner for the fi system and trans.

[Loyd]

make sure the holes in the adapter (tbi 2 carb) are the same size as the tbi you are using. if mismatched can cause a very hard to find vacuum leak. also check the length of the tbi hold down bolts. the stock ones may be a bit too long. good luck