carb for 454
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
carb for 454
I'm looking at getting a new car for the 454 but I'm a little bit at a loss of what to get. Its a pretty much stock 73 engine only has headers and a mild cam the PO put in it. I'm thinking I want to go the double pumper route but could be persuaded otherwise I guess. When I originally looked at it I was going to go with a 750 dp but was told to go bigger and go around 950. I was talking about it with a guy at work today who has been doing racing and the sort for around 20 years and he said he though I shouldn't go any bigger than 750...now I'm just confused and don't have a clue. Suggestions? Oppinions?
Drifting
Joined: Jan 2006
Posts: 1,832
Likes: 38
From: Cedar,BC
I have a 770 Holley Street Avenger on my mild 454.Other than the occasional choke coil acting up(more likely a wiring issue),it seems to work fine.A 750 DP will probably use a lot more fuel and a 950 is waay too big for what you want to do.However unless the baseplate is totally junk on that Q-jet,I would just have a good carb guy rebuild it,I doubt you will get any more power with a new carb.
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
I have a 770 Holley Street Avenger on my mild 454.Other than the occasional choke coil acting up(more likely a wiring issue),it seems to work fine.A 750 DP will probably use a lot more fuel and a 950 is waay too big for what you want to do.However unless the baseplate is totally junk on that Q-jet,I would just have a good carb guy rebuild it,I doubt you will get any more power with a new carb.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Go get you a Holley 4779 (750cfm). Consider an electric choke model. If you went the 4160 route, you'd want to look at a vintage 3310-1 as the preferred vacuum secondary model due to its downleg boosters and factory secondary metering block. But these are swap meet or ebay only at this point in their lives.
Your engine is for the most part, stock. I wouldn't go any bigger than a 4780 (800cfm) double pumper Holley.
If your buddy is good, he can return the current 4160 back to stock, more or less, but it depends on what's been fiddled with on it. If it has drilled-out fuel and air bleeds, then it's going to be a big problem. Most people converted these carbs to mechanical secondary by just putting a screw in the secondary lever. Not very clever, but it was how Bubba used to do it. You just take the screw out and it's back to normal.
Your engine is for the most part, stock. I wouldn't go any bigger than a 4780 (800cfm) double pumper Holley.
If your buddy is good, he can return the current 4160 back to stock, more or less, but it depends on what's been fiddled with on it. If it has drilled-out fuel and air bleeds, then it's going to be a big problem. Most people converted these carbs to mechanical secondary by just putting a screw in the secondary lever. Not very clever, but it was how Bubba used to do it. You just take the screw out and it's back to normal.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
You didn't say if your car is an auto or a 4 speed. With an auto, I'd go with a vacuum secondary carb. The carb can sense when it needs the extra kick from the secondaries a lot better to match the load and trans gear. I've got an 850 Demon on my BB, but I'm also running big heads, big cam and lots of compression. All around driveability will suffer if you get too big a carb. I've had a 650 on mine and it was wicked-- until 5000 RPM. With the 850, it's pretty soft until I get to 3000-3500 RPM and then it rocks pretty good. I've seen the tach at 8000, but I really try to not go there.
Thread Starter
Racer
Joined: Jul 2004
Posts: 450
Likes: 0
From: Fredericksburg VA
You didn't say if your car is an auto or a 4 speed. With an auto, I'd go with a vacuum secondary carb. The carb can sense when it needs the extra kick from the secondaries a lot better to match the load and trans gear. I've got an 850 Demon on my BB, but I'm also running big heads, big cam and lots of compression. All around driveability will suffer if you get too big a carb. I've had a 650 on mine and it was wicked-- until 5000 RPM. With the 850, it's pretty soft until I get to 3000-3500 RPM and then it rocks pretty good. I've seen the tach at 8000, but I really try to not go there.
Melting Slicks
Joined: Aug 2002
Posts: 3,334
Likes: 4
From: Midland TX
People usually put too big a carb on engines thinking bigger hast to be better. This is not always the case.
The Q-Jet has a bad reputation but I think it is a great carb. Small primaries allow good cruising. Vacuum secondaries open as you need them and have plenty of oomph.
I believe the Q-Jet is 750 cfm. Plenty of carb for your use.
I bought a Q-Jet for my 72 454 at Auto Zone. Reasonable price.
My old carb was not original and we could not find a s/n or model # on it anywhere.
I will probably send off the "new" carb to be finetuned and checked out. Plus it has an unfinished silver color instead of the gold color it should be.
The Q-Jet has a bad reputation but I think it is a great carb. Small primaries allow good cruising. Vacuum secondaries open as you need them and have plenty of oomph.
I believe the Q-Jet is 750 cfm. Plenty of carb for your use.
I bought a Q-Jet for my 72 454 at Auto Zone. Reasonable price.
My old carb was not original and we could not find a s/n or model # on it anywhere.
I will probably send off the "new" carb to be finetuned and checked out. Plus it has an unfinished silver color instead of the gold color it should be.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Not sure what intake you're palnning, but take in to consideration your hood clearance. And if you wish to run the stock cowl induction set-up, you're likely stuck with a GM spread-bore intake for Vettes.
I second the Q-Jet opinion above,..great carb for what you're doing.
I second the Q-Jet opinion above,..great carb for what you're doing.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Racer
Joined: Oct 2004
Posts: 318
Likes: 0
On my 454 I have a Holley 770 Street Avenger that Lars rejetted with 74's in the primary and 81's in the secondary with a lighter secondary spring. With the dist. curve that we also done, when you stick your foot in it, you better hold on! Big Blocks Rule 
I also have a 4spd car.
Later, Dave
I also have a 4spd car.Later, Dave