Big block carb options?
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Big block carb options?
Well I'm about sick of my quadrajet again :rant: , it runs absolutely flawless except for going from high rpm in one gear and then getting out of the throttle push in the clutch switch gears and jump on the throttle again and it lays down for a bit then takes off. due this same scenario at 3500 rpm and you probably won't get this bog, due at at 5500rpm and you sure will. It acts like it's out of fuel going into the next gear. Everything else except this scenario is great, throttle response is good, gas mileage is fairly good given what I'm feeding, starts withiout the use of the accelerator pump in the morning, acceleration while in any one gear is fine all the way to the rev limiter at 5500. As I said perfect except for this problem. Anyway been considering another carb as replacement, the problem is that I have a spreadbore L-36 intake so a spacer would be needed for any holley or demon, etc. that I would use as replacement and hood clearance is at a premium under there. I'd be interested in hearing what others have used to change carbs and retain the stock hood, also suggestion on which carb to go with.
Thanks
:cheers:
Pat Kunz
Thanks
:cheers:
Pat Kunz
Melting Slicks
Joined: Dec 2000
Posts: 2,198
Likes: 2
From: Eastern Connecticut
Re: Big block carb options? (73 LS-4)
I take it you are shifting quickly? There are ways to get fuel out faster when the air door first opens, I think by drilling out the little fuel holes in front of the air door edge. Maybe the door just isn't opening fast enough? Don't give up, send an e-mail to Lars, he has all kinds of Q-jet knowledge in his tech papers, and will e-mail them to you.
No good will come from an adapter between a square bore carb and a spread bore manifold. You'll just create different problems.
Joe
No good will come from an adapter between a square bore carb and a spread bore manifold. You'll just create different problems.
Joe
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Re: Big block carb options? (73 LS-4)
Hey Pat,
I have run a Holley Avenger 770cfm on my 73 LS-4 and it ran great. I used the adaptor - spacer for square bore to spread bore. Bought the one at Autozone for $15. Took a little plumbing work with the power brake line and other hoses along with the fuel line. Cut the steel fuel line and ran a rubber fuel hose into the Holley double feed assembly. The stock throttle lines will work, just need a little bending etc. You also need to pick up +12 from the throttle solenoid for the electric choke on the Holley.
I was able to use a 14" Chevy air cleaner and a reduced size filter, think it was a 2" instead o fthe 3 1/2". It cleared the stock hood ok. Thanks to the cowl induction recess.
How did it run - smooth and plenty of power. Your problem may be something other than the carb. Do you have sufficient fuel pump pressure? Do you have a kinked "S" hose? Is your float set too low for not enough fuel in the bowl?
I have run a Holley Avenger 770cfm on my 73 LS-4 and it ran great. I used the adaptor - spacer for square bore to spread bore. Bought the one at Autozone for $15. Took a little plumbing work with the power brake line and other hoses along with the fuel line. Cut the steel fuel line and ran a rubber fuel hose into the Holley double feed assembly. The stock throttle lines will work, just need a little bending etc. You also need to pick up +12 from the throttle solenoid for the electric choke on the Holley.
I was able to use a 14" Chevy air cleaner and a reduced size filter, think it was a 2" instead o fthe 3 1/2". It cleared the stock hood ok. Thanks to the cowl induction recess.
How did it run - smooth and plenty of power. Your problem may be something other than the carb. Do you have sufficient fuel pump pressure? Do you have a kinked "S" hose? Is your float set too low for not enough fuel in the bowl?
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: Big block carb options? (73 LS-4)
you need to drill out the secondary well feeds. get doug roes book and it shows it clearly how to do this. i have done this on drag race and circle track Q jets and it works.
Instructor
Joined: May 2003
Posts: 125
Likes: 0
From: Lexington KY
Re: Big block carb options? (73 LS-4)
I suggest leaving the Q-jet alone, don't drill it, don't fill it just find someone that understands how they work and you won't believe how good they really are. ...But if you choose to replace you will need a holley list # 6210 this is a double pump q-jet performance replacement carb. They have mechanical secondaries and work very well with a four speed with just about any gear ratio. May not supply enough fuel if your heads and cam move alot of air. Another option is the 850 CFM version but I can't for the life of me remember the list number. I see them often on Ebay and the last one I bought was $90. Both of these carbs are a perfect bolt on and fit under the hood, no hacking, no chopping and no mickey mouse fuel line changes. Stock air cleaner also works.
Good luck.
Good luck.
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Re: Big block carb options? (bigvette1)
Hey Pat,
I have run a Holley Avenger 770cfm on my 73 LS-4 and it ran great. I used the adaptor - spacer for square bore to spread bore. Bought the one at Autozone for $15. Took a little plumbing work with the power brake line and other hoses along with the fuel line. Cut the steel fuel line and ran a rubber fuel hose into the Holley double feed assembly. The stock throttle lines will work, just need a little bending etc. You also need to pick up +12 from the throttle solenoid for the electric choke on the Holley.
I was able to use a 14" Chevy air cleaner and a reduced size filter, think it was a 2" instead o fthe 3 1/2". It cleared the stock hood ok. Thanks to the cowl induction recess.
How did it run - smooth and plenty of power. Your problem may be something other than the carb. Do you have sufficient fuel pump pressure? Do you have a kinked "S" hose? Is your float set too low for not enough fuel in the bowl?
I have run a Holley Avenger 770cfm on my 73 LS-4 and it ran great. I used the adaptor - spacer for square bore to spread bore. Bought the one at Autozone for $15. Took a little plumbing work with the power brake line and other hoses along with the fuel line. Cut the steel fuel line and ran a rubber fuel hose into the Holley double feed assembly. The stock throttle lines will work, just need a little bending etc. You also need to pick up +12 from the throttle solenoid for the electric choke on the Holley.
I was able to use a 14" Chevy air cleaner and a reduced size filter, think it was a 2" instead o fthe 3 1/2". It cleared the stock hood ok. Thanks to the cowl induction recess.
How did it run - smooth and plenty of power. Your problem may be something other than the carb. Do you have sufficient fuel pump pressure? Do you have a kinked "S" hose? Is your float set too low for not enough fuel in the bowl?
:cheers:
Pat Kunz
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Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Re: Big block carb options? (clem zahrobsky)
you need to drill out the secondary well feeds. get doug roes book and it shows it clearly how to do this. i have done this on drag race and circle track Q jets and it works.
Thanks
Pat Kunz
