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Topic: Holley Carb replacement suggestions

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


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Holley Carb replacement suggestions (1/11)
 5/20/22 11:02pm
Mark Laird
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Milford, DE - USA

Vette(s):
1977 C3 Auto Coupe Lt Blue/Dk Blue Prev. 1968 C3 convertible 4spd Red 1984 C4 Automatic Silver 2000 C5 Automatic Black


Joined: 11/6/2021
Posts: 57

I would like to know what Holley Carb. would bolt right on my all stock L48 auto with air. It has Vacumn secondary and electric choke. I assume its a spreadbore because of the stock looking manifold. It has a Holley( see pic) on it now but it's over 22 years old and probaby better to just replace it. Any ideas on a perfect replacement? 

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Re: Holley Carb replacement suggestions (2/11)
 5/20/22 11:15pm
F4Gary
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Grapevine, TX - USA

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


Joined: 8/26/2006
Posts: 1138

I put a Holley Street Avenger 670 on my LT-1. 



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Re: Holley Carb replacement suggestions (3/11)
 5/21/22 12:50pm
Mark Laird
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Milford, DE - USA

Vette(s):
1977 C3 Auto Coupe Lt Blue/Dk Blue Prev. 1968 C3 convertible 4spd Red 1984 C4 Automatic Silver 2000 C5 Automatic Black


Joined: 11/6/2021
Posts: 57

Thanks for the info. I don't think thats a spreadbore carb. If I used that I would need a adapter plate?

Re: Holley Carb replacement suggestions (4/11)
 5/21/22 2:59pm
RedwingvetteLifetime Member
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Waterford, MI - USA

Vette(s):
1973 Red coupe


Joined: 9/13/2002
Posts: 1696

I replaced my Q-jet with a Holly 4175 spreadbore

i can’t believe how the cost have gone up on these

bought mine at Summit 

https://www.summitracing.com/parts/hly-0-80555c



|UPDATED|5/21/2022 11:59:33 AM (AZT)|/UPDATED|


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Brian - NCM Lifetime Member

73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, F-body seatbelts, Pioneer CD player
Magnaflow Exhuast System

Dewitt radiator and dual electric fans
Borgeson Steering box
 


Re: Holley Carb replacement suggestions (5/11)
 5/21/22 5:36pm
Mark Laird
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Milford, DE - USA

Vette(s):
1977 C3 Auto Coupe Lt Blue/Dk Blue Prev. 1968 C3 convertible 4spd Red 1984 C4 Automatic Silver 2000 C5 Automatic Black


Joined: 11/6/2021
Posts: 57

Yeah thats crazy..Thinking about changing manifold to Edelbrock and do away with the spreadbore.

Re: Holley Carb replacement suggestions (6/11)
 5/21/22 8:43pm
NorskyLifetime Member
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Twin Lakes, CO - USA

Vette(s):
SOLD - "The Toy" - 1970 Convertible
SOLD - "The Beast" - 1990 ZR-1 (#682)
"BLKBRRD" - 1978 Trans Am, 400ci/225hp, 4 spd, Black w/black interior, Hurst t-tops


Joined: 1/23/2002
Posts: 7000

A spread bore actually is a good carb.  With the primaries being smaller they sip a little less fuel when cruising.  And the larger secondaries add a punch when you mash the go pedal.



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Re: Holley Carb replacement suggestions (7/11)
 5/21/22 9:04pm
Mark Laird
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Milford, DE - USA

Vette(s):
1977 C3 Auto Coupe Lt Blue/Dk Blue Prev. 1968 C3 convertible 4spd Red 1984 C4 Automatic Silver 2000 C5 Automatic Black


Joined: 11/6/2021
Posts: 57

Just can't believe the prices on them..I've seen anywhere from $657.00 to $900.00 for the exact same carb! 

Re: Holley Carb replacement suggestions (8/11)
 5/22/22 12:37pm
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 752

Your cheapest option would be to rebuild your existing spreadbore. The next option that I would entertain would be to get a good Q-jet and put on it.



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1973 L-82 4 spd

Re: Holley Carb replacement suggestions (9/11)
 5/22/22 4:52pm
Mark Laird
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Milford, DE - USA

Vette(s):
1977 C3 Auto Coupe Lt Blue/Dk Blue Prev. 1968 C3 convertible 4spd Red 1984 C4 Automatic Silver 2000 C5 Automatic Black


Joined: 11/6/2021
Posts: 57

I was thinking about rebuilding it but it's aleast 20+ years old. 

Rather just get something newer. Open to the Q-Jet idea however they're just as old.






|UPDATED|5/22/2022 1:52:01 PM (AZT)|/UPDATED|
Re: Holley Carb replacement suggestions (10/11)
 5/23/22 12:59pm
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 752

Mine's almost 50 years old and I'm getting ready to rebuild it again. Check out Cliff Ruggles book on Q-jets on how to rebuild and modify them. He also sells the rebuild kit for a reasonable amount of money.

The only thing I remember about a Holley Spreadbore is that I had a friend back in the seventies that put one on his '72 and not too long afterwards, put his Q-jet back on.



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1973 L-82 4 spd

Re: Holley Carb replacement suggestions (11/11)
 5/29/22 2:59am
Steevo
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San Diego, CA - USA

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


Joined: 11/10/2013
Posts: 25

Like 73Shark said, there's nothing wrong with Q-Jets. 650 CFM IIRC? Relatively easy to rebuild, R&R, and tune. Not the best MPG, but come on: we didn't buy these cars for their fuel economy and save gas! 😄

Steve



|UPDATED|5/28/2022 11:59:33 PM (AZT)|/UPDATED|


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