MSD Atomic EFI
Race Director
Joined: Mar 2016
Posts: 14,331
Likes: 8,139
From: Napa Valley California
My research and best judgement after having done this would suggest that you will have to have a junction somewhere around the rear frame kickup if using hardline. You likely can't make those angles with the body in place.[/QUOTE]
My body will be coming off so it will not be a problem. If it wasn't, I would probably do like you and use braided.
My body will be coming off so it will not be a problem. If it wasn't, I would probably do like you and use braided.
Advanced
Joined: Mar 2015
Posts: 79
Likes: 3
From: winter fl
Return line for atomic mass EFI?
I'm running it.
https://www.corvetteforum.com/forums...post1596347426
As said, I prefer having the computer control timing. It made for a much smoother experience. I'm at the point now where most things are better than they were with the carb. Cold starts, A/C at idle, high gear cruising. It's been long enough now without a carb that I don't even really remember what was better.
It's the best way to get electric fan control and an IAC so A/C engagement doesn't completely bog down your setup like it does w/ a carb+idle stop solen kitoid.
Let me know what you'd like to know. I did the entire install myself, nose-to-tail. OK, I didn't weld in the O2 bung.
https://www.corvetteforum.com/forums...post1596347426
As said, I prefer having the computer control timing. It made for a much smoother experience. I'm at the point now where most things are better than they were with the carb. Cold starts, A/C at idle, high gear cruising. It's been long enough now without a carb that I don't even really remember what was better.
It's the best way to get electric fan control and an IAC so A/C engagement doesn't completely bog down your setup like it does w/ a carb+idle stop solen kitoid.
Let me know what you'd like to know. I did the entire install myself, nose-to-tail. OK, I didn't weld in the O2 bung.
Advanced
Joined: Mar 2015
Posts: 79
Likes: 3
From: winter fl
Atomic vs Sniper
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
I'd really much rather run a port setup like Edelbrock Pro-Flo, though, and get the benefits of sequential fuel injection. By the time you've properly built out a fuel system to support TB-EFI, you're an intake manifold swap away from doing port Fuel Injection - assuming your state lets you do it.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
Kind of bringing this back from the dead. I'm looking over the instructions and wanted to double check something with those of you who has the system in a C3.
I want to continue to use the stock tachometer, but the NEG coil tach signal goes to the EFI harness. The instructions say I can use the yellow wire from the EFI harness for the tach, I took a look and see my tach wire also seems to be connected to what appears to be a condenser. Do I just toss it or keep it? If keep then connected on the wire now just feeding my tach or to the wire feeding the EFI harness?
The kit should be arriving later this week so just getting prepared.
I want to continue to use the stock tachometer, but the NEG coil tach signal goes to the EFI harness. The instructions say I can use the yellow wire from the EFI harness for the tach, I took a look and see my tach wire also seems to be connected to what appears to be a condenser. Do I just toss it or keep it? If keep then connected on the wire now just feeding my tach or to the wire feeding the EFI harness?
The kit should be arriving later this week so just getting prepared.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
I bypassed the “condenser”, it’s a tach filter.
Prior to computer controlled timing, I had n MSD Digital HEI module and used the tach out from that to my Atomic EFI, and then the tach wire was hooked up in the usual spot in the distributor.
Now I *think* I’m using the purple/green wire pair from ignition box to distributor and a tach out from.... the MSD 6A IIRC. It’s been a while.
There are lots of wiring guides in the instruction manual, but my tach filter died ages ago, and was never used in the MSD setup.
Prior to computer controlled timing, I had n MSD Digital HEI module and used the tach out from that to my Atomic EFI, and then the tach wire was hooked up in the usual spot in the distributor.
Now I *think* I’m using the purple/green wire pair from ignition box to distributor and a tach out from.... the MSD 6A IIRC. It’s been a while.
There are lots of wiring guides in the instruction manual, but my tach filter died ages ago, and was never used in the MSD setup.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
EDIT to also ask, electrically are the tach and the EFI basically on the same wire sharing the signal? If so that simplifies how I can wire it up.
I’m gonna go google more about the modules now.
Last edited by shok; Mar 8, 2021 at 11:57 PM.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Did the MSD module have all the same lugs as a stock one? And are you saying you ran an additional wire inside the distributor connected directly to the module?
EDIT to also ask, electrically are the tach and the EFI basically on the same wire sharing the signal? If so that simplifies how I can wire it up.
I’m gonna go google more about the modules now.
EDIT to also ask, electrically are the tach and the EFI basically on the same wire sharing the signal? If so that simplifies how I can wire it up.
I’m gonna go google more about the modules now.
I used the new tach wire for Atomic and the one on the distributor for my OEM tach.
I highly recommend having the computer control timing, though.
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Racer
Joined: Aug 2012
Posts: 427
Likes: 20
The MSD module mounts the same, but has a few extra wires coming out of it. tt has a separate ground wire and a tach wire. The tach wire has a cleaner signal than the one on the distributor cap.
I used the new tach wire for Atomic and the one on the distributor for my OEM tach.
I highly recommend having the computer control timing, though.
I used the new tach wire for Atomic and the one on the distributor for my OEM tach.
I highly recommend having the computer control timing, though.
I think eventually I will end up with computer controlled timing at some point. It will be in stages, I'll be happy with a base install that gets thru SMOG in my town to begin with. Thats been a problem in the past even with an EO sticker.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Yup, that's what I did. I got the MSD-8501 kit.
If your goal is to go to computer controlled, it may make more sense to do an ignition box since you'll need that anyway, and that will give you a clean signal for the Atomic without getting a module you'll eventually toss. Let me know and I can do a little more research if you want me to.
If your goal is to go to computer controlled, it may make more sense to do an ignition box since you'll need that anyway, and that will give you a clean signal for the Atomic without getting a module you'll eventually toss. Let me know and I can do a little more research if you want me to.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
Yup, that's what I did. I got the MSD-8501 kit.
If your goal is to go to computer controlled, it may make more sense to do an ignition box since you'll need that anyway, and that will give you a clean signal for the Atomic without getting a module you'll eventually toss. Let me know and I can do a little more research if you want me to.
If your goal is to go to computer controlled, it may make more sense to do an ignition box since you'll need that anyway, and that will give you a clean signal for the Atomic without getting a module you'll eventually toss. Let me know and I can do a little more research if you want me to.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
If you want to future proof your setup, get the MSD 6A and you can use that in lieu of the Digital HEI module. It’s more expensive, but if you decide to go with computer controlled timing, you’d be saving money in the long run by not buying the module. You’ll need the 6A to add computer controlled spark to Atomic.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
I'm sure eventually I will end up with the computer controlling the timing, even if all the effort I put into the stock HEI works great on its own at some point I will need boost retard. I can dream anyway.
I received it earlier this week, starting the slow install now. I'm doing this in the driveway so weather has to cooperate, plus I have a bad back. I'm trying to capture pics and video snippets since I don't see a lot of that for this kit on C3s.
I received it earlier this week, starting the slow install now. I'm doing this in the driveway so weather has to cooperate, plus I have a bad back. I'm trying to capture pics and video snippets since I don't see a lot of that for this kit on C3s.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
I’m wondering if I’m way off base or is my filter mislabeled. The smaller filter that goes before the fuel pump has an arrow indicating which way fuel flows, or so I thought. The end the arrow is pointing at has IN stamped in the metal near the nipple. So it’s contradicting itself.
Any ideas? I tried to call MSD but they were closed early today.
Any ideas? I tried to call MSD but they were closed early today.
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
No don't have a pic, I finally got to speak with tech support less than 5 mins ago and they said just go with the arrow and ignore the stamped IN part.
So I will go with that. Dunno if I will make much progress today since the weather is pretty stormy down here.
Gotta say the tech support guy at Holley seemed to hate his job
So I will go with that. Dunno if I will make much progress today since the weather is pretty stormy down here.
Gotta say the tech support guy at Holley seemed to hate his job
Racer
Joined: Aug 2012
Posts: 427
Likes: 20
Well its been running for over a week, but only really took it on a proper test drive today.
First impression is off the line it's a different car, way more responsive. It's still a pooch of a motor but at least it's much snappier.
All that is left for now is to finalize where I mount the CPU and clean up some wiring. Shark and others with this system in a C3, where did you mount the ECU?
Right now I'm thinking under the shifter area will work. I planned to put it against the HVAC box and 3D printed a nice bracket for that but the dash panel/glove box was just a little too close and killed that idea since I didn't want to cut that panel.
First impression is off the line it's a different car, way more responsive. It's still a pooch of a motor but at least it's much snappier.
All that is left for now is to finalize where I mount the CPU and clean up some wiring. Shark and others with this system in a C3, where did you mount the ECU?
Right now I'm thinking under the shifter area will work. I planned to put it against the HVAC box and 3D printed a nice bracket for that but the dash panel/glove box was just a little too close and killed that idea since I didn't want to cut that panel.