750 CFM on a 454?
Thread Starter
Racer
Joined: Mar 2005
Posts: 287
Likes: 0
750 CFM on a 454?
I'm at the end of my patience. I have a Carter 750 cfm carb on a moderately built 454 fresh rebuild. It drinks gas at a ridiculous rate, and fouls plugs.
I have cleaned/rebuilt the carb 3 times, replaced plugs, and have no vaccum leaks. Also, I adjusted the float levels, and turned off the electric fuel pump, but still no change.
I'm pretty sure that the carb, is not modified in any way.
is it possible that 750 is just too big?
I have cleaned/rebuilt the carb 3 times, replaced plugs, and have no vaccum leaks. Also, I adjusted the float levels, and turned off the electric fuel pump, but still no change.
I'm pretty sure that the carb, is not modified in any way.
is it possible that 750 is just too big?
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Nahh, not too big. I ran a 780 Holley dual-feed on a 327 in my '56 Bel Air. Of course, it had 12:1 TRW's and a solid lifter cam with a shift point of 8500RPM. But still ....
High float levels? Did you recheck the number you are setting them to? Too cold a plug maybe? How much compression per cylinder?
High float levels? Did you recheck the number you are setting them to? Too cold a plug maybe? How much compression per cylinder?
Tech Contributor
Joined: Jun 2004
Posts: 20,931
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I'm at the end of my patience. I have a Carter 750 cfm carb on a moderately built 454 fresh rebuild. It drinks gas at a ridiculous rate, and fouls plugs.
I have cleaned/rebuilt the carb 3 times, replaced plugs, and have no vaccum leaks. Also, I adjusted the float levels, and turned off the electric fuel pump, but still no change.
I'm pretty sure that the carb, is not modified in any way.
is it possible that 750 is just too big?
I have cleaned/rebuilt the carb 3 times, replaced plugs, and have no vaccum leaks. Also, I adjusted the float levels, and turned off the electric fuel pump, but still no change.
I'm pretty sure that the carb, is not modified in any way.
is it possible that 750 is just too big?
Thread Starter
Racer
Joined: Mar 2005
Posts: 287
Likes: 0
Thanks for the sound advice. The 454 is a 10.25 to 1 compression ratio.
I've downloaded a good Carter owners manual with a nice exploded view.
That is mainly how I've educated myself so far.
I want to pursue the jetting issue, but I need to understand the terms as they are labled in the diagram because there are a couple of parts labled "Jets" in the diagram.
Are you refering to the part the metering rods (called "step-up rods" in the diagram) go in?
These are called "Primary metering jets" in the diagram.
By the way, my metering rods are labeled "7147".
I know this is a bit wordy, but none of the terms in the diagram match exactly so I want to make sure I understand all this.
I've downloaded a good Carter owners manual with a nice exploded view.
That is mainly how I've educated myself so far.
I want to pursue the jetting issue, but I need to understand the terms as they are labled in the diagram because there are a couple of parts labled "Jets" in the diagram.
Are you refering to the part the metering rods (called "step-up rods" in the diagram) go in?
These are called "Primary metering jets" in the diagram.
By the way, my metering rods are labeled "7147".
I know this is a bit wordy, but none of the terms in the diagram match exactly so I want to make sure I understand all this.
Tech Contributor
Joined: Jun 2004
Posts: 20,931
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
You might also consider buying a wideband O2 sensor/monitor to see what your actual A/F ratio is. It's a handy item when tuning the fueling system.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
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
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Instructor
Joined: Oct 2009
Posts: 152
Likes: 0
From: Williston Florida
Yeah, what he said. The Carter isn't a carb to learn fuel curves, jetting, etc on. As Motorhead said, score a 750 Holley on ebay (be patient and you can find a good used one for $50-75) plus a rebuild kit ($28). Jet it according to the Holley charts for that model and you'll be in the ballpark. I have a 750 holley (4779) on my mild 454. LOVE IT! It's perfect!
