Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: Marx3 on September 08, 2016, 12:48:25 PM

Title: Increasing cfm
Post by: Marx3 on September 08, 2016, 12:48:25 PM: A friend of mine, who is an avid racer ( Buick fanatic ) is getting ready to put together a new engine. He always runs Qjets.
We have been talking about setting one up for a wild 455. Think he intends to go into the 10's or maybe lower. Pretty serious.
How can I modify a large cfm unit for this? Is it even necessary?
Title: Re: Increasing cfm
Post by: carmantx on September 08, 2016, 09:15:26 PM: What's the horsepower?
The Buick quadrajet from 71-74 can be set up for fast Buicks. 10's aren't a problem.
Title: Re: Increasing cfm
Post by: Marx3 on September 09, 2016, 02:35:34 PM: Not sure about the HP rating yet. I know Cliff supports about 650 horses with a large cfm unit. Dont know if it has been touched in places...:-)

My friend is romanticizing this abit I think. He wants 900+ cfm, just for the heck of it.
I guess it aint even necesary at all...
I wonder at what displacement the large cfm units falls short... or what HP.
Title: Re: Increasing cfm
Post by: carmantx on September 09, 2016, 04:18:23 PM: I run mine on a 464 in mid 500 hp range and a 462 at about 500. I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.
Title: Re: Increasing cfm
Post by: 77cruiser on September 09, 2016, 06:04:17 PM: Quote from: carmantx on September 09, 2016, 04:18:23 PM
I run mine on a 464 in mid 500 hp range and a 462 at about 500. I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.
What's the rest of your fuel system tank to pump?
Title: Re: Increasing cfm
Post by: carmantx on September 09, 2016, 08:49:30 PM: On the 462, I have 1/2" line from tank to a mechanical pump.
On the 464, fuel cell and braided hose with electric pump and regulator.
Title: Re: Increasing cfm
Post by: Marx3 on September 10, 2016, 02:41:14 AM: Quote from: carmantx on September 09, 2016, 04:18:23 PM
I run mine on a 464 in mid 500 hp range and a 462 at about 500. I built one for a 570 ci.
If I remember right, there was about 3 hp difference on dyno compared to 950.

3hp difference from a 950 cfm! cool.
Do you remember the air flap opening distance?
Title: Re: Increasing cfm
Post by: carmantx on September 10, 2016, 05:27:39 AM: 1.30" I believe.
Title: Re: Increasing cfm
Post by: Marx3 on September 10, 2016, 09:32:09 AM: pheew, that sure means open.
I seem to remember, that the flaps can open too much, slowing down the incoming air. Dont remember at what opening distance this happens.
Title: Re: Increasing cfm
Post by: 77cruiser on September 10, 2016, 01:43:46 PM: Now you got me thinking that I might have mine open too far.
Title: Re: Increasing cfm
Post by: Marx3 on September 11, 2016, 07:55:48 PM: Haha oh no!
How far does your open?
I thinks it's in the book, even?
Gotta see if I can look up the max distance.
Title: Re: Increasing cfm
Post by: 77cruiser on September 12, 2016, 06:03:28 AM: I think I have one of them at 1.28.
Title: Re: Increasing cfm
Post by: von on September 13, 2016, 02:17:11 AM: What method is used to measure it?
Title: Re: Increasing cfm
Post by: dlong70elcamino on September 15, 2016, 11:16:37 PM: I've got mine set at the max of 1.270 on a 750 cfm unit on a built 350 Chevy works great its drag raced weekly......Dan
Title: Re: Increasing cfm
Post by: Ethan1 on September 16, 2016, 02:05:19 AM: Quote from: von on September 13, 2016, 02:17:11 AM
What method is used to measure it?

Von,
See if this website helps?

http://www.mre-books.com/quadrajet/edelbrock.html
Title: Re: Increasing cfm
Post by: von on September 16, 2016, 02:19:37 AM: Thanks Ethan. Looks about the same as shown in Cliff's book but I've always had trouble getting a good consistent measurement.
Title: Re: Increasing cfm
Post by: Marx3 on September 16, 2016, 12:42:52 PM: never heard of those "tabs" in the air flaps... I wonder if they are worth a shot? on a mild SBC...