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Topic: EFI recommendation

in Forum: C3 Fuel, Emission Control, and Exhaust Systems


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EFI recommendation (1/9)
 1/26/24 4:05pm
Dblancha79Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 383 cu in


Joined: 6/29/2015
Posts: 79

When I bought my C3 it had a Holly Pro-injection EFI system. I pulled it off as I could never get the car to idle properly and installed a standard Edelbrock four-barrel carburetor. I have since had the engine reworked to 383 stroker with aluminum heads and would like to improve the fuel distribution. Any recommendations on a decent EFI set up.  Engines putting out about 415 hp.  Summit Racing has a Max-efi 500 does anyone have an experience with this model? Any help would be appreciated.  (I'm still fighting hard starting after I run the car for a little while and am convinced its vapor lock of fuel pressure related) EFI would solve this.



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"Made to be run hard"
Simsbury, Ct.

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Re: EFI recommendation (2/9)
 1/26/24 5:54pm
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box


Joined: 7/3/2016
Posts: 319

A few years ago I installed Holley's Sniper EFI on my '75.  It is very tunable and provided a noticable power improvement.  The reason I went with EFI was I could never get the Holley dual-pumper carb to run right.  There is a Holley forum with experts that provide a lot of great support.  One even created a custom config setup for mine.

Holley just came out with a new version; Sniper2, which appears to be going through some growing pains, but provides even more features when it is all sorted out.

 



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Re: EFI recommendation (3/9)
 1/26/24 10:32pm
F4GaryGold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1399

I think the Holley Sniper is newer and improved over the efi you had.  You don't need a return fuel line now either.



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Re: EFI recommendation (4/9)
 1/27/24 9:30am
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box


Joined: 7/3/2016
Posts: 319

F4Gary said:

I think the Holley Sniper is newer and improved over the efi you had.  You don't need a return fuel line now either.

The Sniper2 also eliminated the internal fuel pressure regulator that had been problematic.  I just replaced mine with an external pressure regulator.




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Re: EFI recommendation (5/9)
 1/27/24 11:49pm
NorskyLifetime Member
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West Burke, VT - USA

Vette(s):
SOLD - "The Toy" - '70 Convertible
SOLD - "The Beast" - '90 ZR-1 (#682)
SOLD - "Betty" - '28 Ford Model A Tudor
Still have - "BLKBRRD" - '78 Pontiac Trans Am


Joined: 1/23/2002
Posts: 7186

In 2016 I purchased a 1st gen FITECH system for "BLKBRRD" and it took several years to get it sorted out.  Then the fuel pump died while at the Ft Worth Gathering.  Last year the computer died so I just had enough fooling around with it and not trusting it.  So had the original Q-Jet rebuilt and reinstalled on the car.

Whatever system you decide to go with two suggestions:

  1. use an in-tank fuel pump with it
  2. use a return line

Don't let price be the major factor in whatever system you decide on.  That's what I did, unfortunately, and in the end it cost me more.  Go with a system that has the best reliability.



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Jim Olson 

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Re: EFI recommendation (6/9)
 1/28/24 10:18am
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition Vintage Air air conditioning Borgeson power steering box


Joined: 7/3/2016
Posts: 319

I used an external fuel pump.  My gas tank is the bladder type, so cutting another hole in it for a pump was not possible.  There are EFI gas tanks for most Corvettes, but none that I could find for my '75.  The whine from the pump is quite noticeable, but so far the system has been pretty reliable.

I suppose it would have been possible to modify the in-tank assembly to include a fuel pump, but that seemed a bit complicated at the time.

 



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Re: EFI recommendation (7/9)
 1/28/24 3:04pm
F4GaryGold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1399

Holley has an in tank fuel pump that doesn't need an external return line.  It does it internally in the tank.  It is for stock tanks.

 

https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/fuel_pumps/muscle_car_efi_modules/parts/12-312



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Re: EFI recommendation (8/9)
 2/7/24 1:39pm
Steevo
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San Diego, CA - USA

Vette(s):
'73 L48 Coupe, 383, M20, A/C, Electric Windows. Matterhorn White Jet-Glo w/ Dark Blue interior. Rochester, Edelbrock, Blackjack Ceramics, Borlas w/ 2.5" mandrel X over, Cooper Cobras on both OEM Steel and Aluminum Wheels.


Joined: 11/10/2013
Posts: 51

As we know, EFI systems are electronic dependent as well as computer operated. Rochesters and Holleys aren't. If you are willing to risk the potential malfunctions of an EFI system ( poor running, stalling, unplanned engine shutdown, auto towing, etc) for the potential benefits of quicker performance response and better mpg's, good luck to ya. For me, it was a two thousand dollar mistake. I am now very happy with with the stock Rochester in my 383.

Steve



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Re: EFI recommendation (9/9)
 2/7/24 4:11pm
Dblancha79Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 383 cu in


Joined: 6/29/2015
Posts: 79

I think I solved my hard starting issue after the car gets hot. I installed a $22 dollar vapor separator fuel filter I saw on youtube. It has a return port to the gas tank and the fuel pressure drops to zero as soon as the car shuts off. Before it was staying at 5psi and sometimes increasing to 8 psi sitting hot which I think was causing the vapor lock. It starts right up now but I will have to wait to the hot summer months to see if it's fully resolved. I'm old school and would love to stay with the carburetor set up.



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"Made to be run hard"
Simsbury, Ct.

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