X3
Carb. Suggestion ;)
Thread Starter
Racer
Joined: Feb 2012
Posts: 462
Likes: 0
From: Virginia
Carb. Suggestion ;)
Im sure it has been covered before..but my application is a little different:
my '73 Corvette has a Chevy 402 no modifications , MSD Distrib. with MSD Box. The vacum is ok ..not great.
I drive it to car shows and occasional trips.
Which carburetor should I buy:
Quick Fuel 600cfm (Quick Fuel SL600VS)
or
Road Demon 625cfm (4282010VE)
I tried a QF 600cfm and it runs great...just a little hesitation when going from stopped... if I slowly push the gas paddle All is good..only if I really push it ..it hesitates at first and then it goes
I was thinking 650cfm may resolve the issue.
I believe 750 cfm is too much for my engine...any suggestion on the two brands and cfm I should go with?
Thanks
my '73 Corvette has a Chevy 402 no modifications , MSD Distrib. with MSD Box. The vacum is ok ..not great.
I drive it to car shows and occasional trips.
Which carburetor should I buy:
Quick Fuel 600cfm (Quick Fuel SL600VS)
or
Road Demon 625cfm (4282010VE)
I tried a QF 600cfm and it runs great...just a little hesitation when going from stopped... if I slowly push the gas paddle All is good..only if I really push it ..it hesitates at first and then it goes
I was thinking 650cfm may resolve the issue.
I believe 750 cfm is too much for my engine...any suggestion on the two brands and cfm I should go with?
Thanks
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Rebuild a Quadrajet for it. It will get better fuel economy and should run great.
What carb is on it now? You probably need to tune your existing carb. Are you running vacuum secondaries?
What carb is on it now? You probably need to tune your existing carb. Are you running vacuum secondaries?
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I've never tuned one, however I found this on quick fuel's site.
http://www.quickfueltechnology.com/t...e-bog-the-boot
http://www.quickfueltechnology.com/t...e-bog-the-boot
Thread Starter
Racer
Joined: Feb 2012
Posts: 462
Likes: 0
From: Virginia
I've never tuned one, however I found this on quick fuel's site.
http://www.quickfueltechnology.com/t...e-bog-the-boot
http://www.quickfueltechnology.com/t...e-bog-the-boot
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
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
I can tell you a 750 is NOT too much for it....
600's are for very mild 327/350's....
JIM
600's are for very mild 327/350's....
JIM
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
750 cfm carb is not too much for it if the carb is a Quadra-Jet or a square-bore carb with vacuum operated secondaries. 750 cfm is probably too much for it if it has just a 'dumper' secondary on it.
Q-Jet secondaries regualte the flow into the engine depending on the engine's capabilities...not the carb's. A vacuum secondary system attempts to duplicate that approach. Otherwise, the carb's A/F flowrate needs to match what the engine requires...or you get lean or 'fat' conditions at WOT.
But, just purchasing ANY new carb is not the solution; it's just the first step.
Q-Jet secondaries regualte the flow into the engine depending on the engine's capabilities...not the carb's. A vacuum secondary system attempts to duplicate that approach. Otherwise, the carb's A/F flowrate needs to match what the engine requires...or you get lean or 'fat' conditions at WOT.
But, just purchasing ANY new carb is not the solution; it's just the first step.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
It would probably be a bit more helpful to know more about your current setup. Based on your profile, I take it you have a 402 Big Block, correct?
What trans and rear gears are you running?
What cam and intake manifold are you using right now?
Good luck... GUSTO
What trans and rear gears are you running?
What cam and intake manifold are you using right now?
Good luck... GUSTO
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Have not owned one but quick fuel seems to have established a good rep on carbs if your going to buy a new carb.
A 402 big block even a stock one needs a 750 size carb. Think of how much more air the heads and intake manifold can flow on it along with its exhaust flow in comparison to any factory SBC head and intake manifold at all rpms levels you drive the car at from idle on up. Using to small a carb on it does nothing for you but hurt you. Look into a vacuum secondary from quick fuel 750 for what you describe you want to do with your car. Quick fuel seems to give a lot of the more fine tune adjustable in there carb for there cost.
If you want to mess with an old carb there would be nothing wrong with using a 750 Q-jet on it.
A 402 big block even a stock one needs a 750 size carb. Think of how much more air the heads and intake manifold can flow on it along with its exhaust flow in comparison to any factory SBC head and intake manifold at all rpms levels you drive the car at from idle on up. Using to small a carb on it does nothing for you but hurt you. Look into a vacuum secondary from quick fuel 750 for what you describe you want to do with your car. Quick fuel seems to give a lot of the more fine tune adjustable in there carb for there cost.
If you want to mess with an old carb there would be nothing wrong with using a 750 Q-jet on it.
Last edited by Little Mouse; Oct 11, 2015 at 10:56 AM.
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
Your idling off the transition slots , that causes the issue you describe .. I would also suspect that when you try to adjust the idle A/F you get little or no change ..
If I am on target ... Set the transition slots and adjust curb idle off the 2 back butterflies using an allen wrench ( It may need to be ground to a flat head I forget ) , it is sort of tricky but easily doable
If I am on target ... Set the transition slots and adjust curb idle off the 2 back butterflies using an allen wrench ( It may need to be ground to a flat head I forget ) , it is sort of tricky but easily doable
Thread Starter
Racer
Joined: Feb 2012
Posts: 462
Likes: 0
From: Virginia
Your idling off the transition slots , that causes the issue you describe .. I would also suspect that when you try to adjust the idle A/F you get little or no change ..
If I am on target ... Set the transition slots and adjust curb idle off the 2 back butterflies using an allen wrench ( It may need to be ground to a flat head I forget ) , it is sort of tricky but easily doable
If I am on target ... Set the transition slots and adjust curb idle off the 2 back butterflies using an allen wrench ( It may need to be ground to a flat head I forget ) , it is sort of tricky but easily doable
