BachelorOfScience

I was looking at a 79 C3 today that, when demonstrated, had a very rough idle and was always on the verge of stalling out. My friend who was with me said that if he were to buy the car, the first thing he'd do is convert to EFI. The car is pretty nice in other respects but if I do buy it, I want to avoid issues like stalling at a red light. So what's the general advice on converting a 45 year old car to EFI? Holley Sniper? What's the ballpark cost for a guy to pay a mechanic to have it done? Should I go to a speed shop? Thanks. 👍

Arg0413

What's causing the stall? Is this a 4 speed or auto? Is the rest of the drive train correctly spec'd for your cam? ( gears & stall)?

For EFI I like the Edelbrock Pro Flow to have true port injection. The snipers work well , but all systems will require tuning to work correctly with your car and big cam you're running .

4-vettes

I run a fair bit of cam in my 77 with EFI. yes my car runs great. Yes it took a LOT to dial it in.
pay someone else?
WOW! best of luck.

BachelorOfScience

The car is a 3-spd auto. That's as much as I know about the drivetrain. I think I may pass on this car, but my buddy made pretty convincing arguments for conversion to EFI, if you want the car to start and run like a more modern vehicle (which is a genuine concern, as I'm looking forward to handing the car down to one of my children in a few years).

So, what do you think? EFI, Edelbrock or Holley, whichever in your opinion would be the most reliable. I read elsewhere that to get it done right the first time, you should probably find a speed shop to do it; guys that have real experience doing this work.

BachelorOfScience

That's the key; I want a car that will run great. I don't want to worry about it dying on me when stopped at a red light, especially for the child who will inherit it in a few years.

augiedoggy

So holley recently released a newer version of the sniper and the guys at roadkill garage used it on one of their builds. engine masters also did an episode on it (same guys). Take this for what its worth because they are a sponsor but according to them its leaps and bounds better than the sniper and one of the things they said was the auto learning actually works and was easy to manually tweak as well even without a laptop.

4-vettes

To the OP, I personally believe it doing it myself. Can't imagine what it would cost to have it done.
most shops that specialise in older cars can handle the installation, and then palm it off to a good dyno shop for tuning.
What would all that cost?
It will really depend on the car itself, your location and the type of system that you choose to run.
If you were serious, you could place a few calls to shops in your area for price estimates.

shok

I converted my 77 with the original Atomic EFI kit, I did the work myself but I’m experienced so it didn’t seem like a big deal. I have the benefits mentioned but what you are describing with that car could also happen with a poorly maintained EFI car. A well maintained and tuned stock carb can run really well, the selling point for me was I don’t drive my vette daily and I don’t want to do excessive cranking etc to get fuel up to the carb, with EFI the car can sit for a couple of weeks (need the battery on a trickle charger though) and start on the first try.

BPHORSEGUY

When my C3 sits for more then a couple weeks I pop the Air Cleaner off and pour an ounce ( shot ) of fuel in the carb. It takes me about 2 minutes to do and I have a small squirt bottle of fuel to do it ! it usually starts after about 1 second of cranking !

ULTM8Z

If the car is stalling because of some mechanical or ignition problem, the solution isn't necessarily to throw EFI on it. EFI does not compensate for problems... all you have to do is go over to the C4 section and see how many people are complaining about idle surging, rough idles, stalling etc...

If the problem is the carburetor itself and everything else is fine, then EFI is certainly an option. But if it's ignition, or some other issue, it'll only become more frustrating when EFI is thrown into the mix.

Bikespace

For what it will cost to have a mechanic install a Sniper EFI kit, you can LS-swap your car instead. You get EFI, and you also get (for free) a roller cam, high-flow aluminum heads, 30+ years of engineering improvements, and the best aftermarket support of any engine in the world.

https://www.corvetteforum.com/forums...into-a-c3.html

shok

I used to do that with my ‘66 Chevy truck and others, I prefer the EFI route.