Carburetor choices
Thread Starter
7th Gear
Joined: Dec 2004
Posts: 7
Likes: 0
From: Austin Texas
Carburetor choices
Hey guys,
I'm trying to decide which carburetor to buy for my 1973 Vette.
350 L-82 motor with stock carb. and intake. Trying to add a little more umph! Already running 2-1/4" exhaust pipes with airturbines, so I thought a 700/750 cfm carb was in order.
Any suggestions on a Holley that would fit would be much appreciated. Thanks!
I'm trying to decide which carburetor to buy for my 1973 Vette.
350 L-82 motor with stock carb. and intake. Trying to add a little more umph! Already running 2-1/4" exhaust pipes with airturbines, so I thought a 700/750 cfm carb was in order.
Any suggestions on a Holley that would fit would be much appreciated. Thanks!
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by Mr. JZR
Hey guys,
I'm trying to decide which carburetor to buy for my 1973 Vette.
350 L-82 motor with stock carb. and intake. Trying to add a little more umph! Already running 2-1/4" exhaust pipes with airturbines, so I thought a 700/750 cfm carb was in order.
Any suggestions on a Holley that would fit would be much appreciated. Thanks!
I'm trying to decide which carburetor to buy for my 1973 Vette.
350 L-82 motor with stock carb. and intake. Trying to add a little more umph! Already running 2-1/4" exhaust pipes with airturbines, so I thought a 700/750 cfm carb was in order.
Any suggestions on a Holley that would fit would be much appreciated. Thanks!
Holly is not the where all, be all, that many make it out to be.
I am assuming that you have a Q-Jet.
Get some technical books on how engines operate. A Q-Jet is at least 750 cfm, and because of its design, will work on a stock 350, where as a Holly 700-750 will probably overcarb the engine.
If a rebuild is needed, check with Lars.
BTW, what are exhaust airturbines?
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
I got to agree with the above. A good working Q-jet is fine. A bad working Q-Jet is a different story. I would suggest a 600 or 650 cfm Holley if you want to go that route. A 750 is pushing it even for a high performance, high rpm 350. Going from a 650 to 750 may get you 2 or 3 more horses, but the car will definetly have a better punch at 1500 rpm with the 650.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
You would do better to get a set of headers on this engine. Then put turbo mufflers and 2.5" exhaust pipe all the way to the rear bumper. Tune your carburator to match this combo, you may find this is all you need.
If not, then take the heads off and get a street port job done on them. While the heads are off you really should change the intake manifold with something conservative form Edelbrock. A cam change would be real easy to do while the heads and intake are off. Don't go wild here, just a little more lift and duration than stock. Retune the carburator to match the new air flow characteristics of the engine.
This is going to have you in the 320 to 340 horse power range. You'll notice that that nasty old Quadrajet carburator is still there. If you need more than this put a blow through turbocharger on it.
Recalibrate that nasty old Quadrajet to work with the blower.
Hope this helps.
BigBlockk
Later.....
If not, then take the heads off and get a street port job done on them. While the heads are off you really should change the intake manifold with something conservative form Edelbrock. A cam change would be real easy to do while the heads and intake are off. Don't go wild here, just a little more lift and duration than stock. Retune the carburator to match the new air flow characteristics of the engine.
This is going to have you in the 320 to 340 horse power range. You'll notice that that nasty old Quadrajet carburator is still there. If you need more than this put a blow through turbocharger on it.
Recalibrate that nasty old Quadrajet to work with the blower.
Hope this helps.
BigBlockk
Later.....
Drifting
Joined: Nov 2002
Posts: 1,951
Likes: 1
From: Shore NJ
Your stock Q jet is rated at 750cfms and can work fine with a good tuning. .I changed the intake to a high rise and was running a Holley 780 vacuum secondary with a good tuning and it ran just fine before I went the cam, heads, headers, and other goodies route....
Last edited by 73jst4fun; Dec 5, 2004 at 11:39 AM.
Pro
Joined: Aug 2000
Posts: 713
Likes: 1
From: plymouth mass
Holley Carb
I am running a Holley 600CFM single feed on a LT1 intake on my 350. I have a 650 double pumper but never installed it. Oh, I have a Comp 268H cam too. The 600 works out great but I am still tempted to try the 650.
Race Director
Joined: Jun 2000
Posts: 10,040
Likes: 672
From: FL
You will see zero increase with a new carb if the Q-Jet is working OK. If you need to tune the Q-Jet, I recommend Lars' papers at www.corvettefaq.com .
My combo: .030 over 350, Edelbrock RPM heads, Edelbrock 2101 manifold, Crane HR276 roller cam (~214/222 @.050), Hooker sidepipes, and a retuned (using Lars' info) Quadrajet.
I get 20 mpg on the highway at cruise and have no traction in 1st or 2nd. Best of both worlds.
Thread Starter
7th Gear
Joined: Dec 2004
Posts: 7
Likes: 0
From: Austin Texas
Thanks for all the input!
Yes, I do have a Q-jet on right now but it runs poorly. My problem occurs up in 3rd and 4th gear at high rpms. When I start to accelerate quickly it begins to bog down, but if I let off and slowly accelerate it works just fine...weird (kinda like it's running too lean)
I did find a refurbished Q-jet for $269.00 but wasn’t sure if I should just bite the bullet and buy a new Q-jet?
I will take some pictures of the airturbines
Yes, I do have a Q-jet on right now but it runs poorly. My problem occurs up in 3rd and 4th gear at high rpms. When I start to accelerate quickly it begins to bog down, but if I let off and slowly accelerate it works just fine...weird (kinda like it's running too lean)
I did find a refurbished Q-jet for $269.00 but wasn’t sure if I should just bite the bullet and buy a new Q-jet?
I will take some pictures of the airturbines
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Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Originally Posted by chuck d
I am running a Holley 600CFM single feed on a LT1 intake on my 350. I have a 650 double pumper but never installed it. Oh, I have a Comp 268H cam too. The 600 works out great but I am still tempted to try the 650.
Race Director
Joined: Jun 2000
Posts: 10,040
Likes: 672
From: FL
Originally Posted by Mr. JZR
Thanks for all the input!
Yes, I do have a Q-jet on right now but it runs poorly. My problem occurs up in 3rd and 4th gear at high rpms. When I start to accelerate quickly it begins to bog down, but if I let off and slowly accelerate it works just fine...weird (kinda like it's running too lean)
Yes, I do have a Q-jet on right now but it runs poorly. My problem occurs up in 3rd and 4th gear at high rpms. When I start to accelerate quickly it begins to bog down, but if I let off and slowly accelerate it works just fine...weird (kinda like it's running too lean)