502 with a quadrajet?
NCM Grand Opening Veteran
Joined: Sep 2005
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From: South of giving a damn
St. Jude Donor '11, '17
The question would have to be why would anyone want to? I'd think the Qjet would have a hard time flowing enough for a mild 502. I'd think 900 - 1000 CFM would be more in the range.
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
Originally Posted by ratflinger
The question would have to be why would anyone want to? I'd think the Qjet would have a hard time flowing enough for a mild 502. I'd think 900 - 1000 CFM would be more in the range.
not to mention a change in intakes as well. 502 intakes are based on the Holley carb.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
I guess it's time to post this again. Look at Greg Gessler's 1972 Buick GS. It has run a best of 11.02 with a 3800 Lb car. That has to be 600 to 650 HP.
http://www.fastraces.org/members/fas...nu-items/ghp28
BigBlockk
Later.....
http://www.fastraces.org/members/fas...nu-items/ghp28
BigBlockk
Later.....
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East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Originally Posted by BigBlockk
The point is that we now know that a Quadrajet will handle 600 to 650 HP no matter what the engine size is. I think it would be neat to have a 'Jet on a 502.
BigBlockk
Later.....
BigBlockk
Later.....
I'm sure there is someone out there that you could send a Q-jet to that could open up the bore size of the venturis a little bit to possibly flow a little bit better.
Last edited by LS-Five; Sep 26, 2006 at 11:11 PM.
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Originally Posted by Kalway
There's an 850CFM q-jet out there somewhere, too. They used to put em on caddys, too.
I suppose that would have been off of the seventies caddies that had the 472's and 500's ? I was unaware that they had an 850, I figured that an 800 was the biggest of the bunch.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
A Q-jet will supoort 500 HP,..it's done repeatedly on the dynos. If you want the original 850 Holley VS Carb that came with your 502 originally, I have it. Almost brand new. It was used to break in a new 502 crate engine then shelved for an 850 DP. $300
Wes
Wes
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 1,211
Likes: 6
The only reason for doing it would be hood clearance concerns in my '69. I am running the stock low rise alum intake w/the quadrajet now (L-36) and was thinking about putting in a 502 but know the hood may not close.
I know this would hurt the power somewhat because of the restrictive nature of this intake.
The Quad I have is the big one that Edelbrock is selling now (RPM) and it is a strong one for sure. I think it's 800 or 850cfm.
This clearance issue is the main problem with our cars in that unless you want to add on an L-88 hood you can't really have the higher performance intakes.
That's my $.02
Thanks, Mark
I know this would hurt the power somewhat because of the restrictive nature of this intake.
The Quad I have is the big one that Edelbrock is selling now (RPM) and it is a strong one for sure. I think it's 800 or 850cfm.
This clearance issue is the main problem with our cars in that unless you want to add on an L-88 hood you can't really have the higher performance intakes.
That's my $.02
Thanks, Mark
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by LS-Five
I'm sure there is someone out there that you could send a Q-jet to that could open up the bore size of the venturis a little bit to possibly flow a little bit better.
I have read alot on these mods which dont look all that difficult
I have not attempted any of them but if I ever have the need Cliff Ruggles book explains them in detail.
http://www.amazon.com/Rebuild-Modify...e=UTF8&s=books
Last edited by Bob Onit; Sep 27, 2006 at 04:38 AM.
Drifting
Joined: Jan 2006
Posts: 1,944
Likes: 22
From: Yooperville MI
If memory serves me correctly, the '73 & '74 Pontiac Super Duty's had an 850 QJ as well.
From my experience with 502's, 850 cfm makes a nice driver, but 1000 cfm wakes them up. Big difference. The big question for hood clearance is the measurement between the top of the airhorn and the bottom of the hood. You can fab a deeper drop base, but the result might be the air cleaner lid is too close to the airhorn for proper flow.
From my experience with 502's, 850 cfm makes a nice driver, but 1000 cfm wakes them up. Big difference. The big question for hood clearance is the measurement between the top of the airhorn and the bottom of the hood. You can fab a deeper drop base, but the result might be the air cleaner lid is too close to the airhorn for proper flow.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
for what it's worth considering that most Q-Jets are 750cfm's........
A friend of mine dropped a ZZ502 in his '65 last year and it came with the Holley carb (or he put on a Holley, don't remember which) that i believe but may be wrong was either a 950 or a 1050. he was never happy with the off idle performance no matter how much he worked to adjust that carb.
Just a few weeks ago he switched out the Holley for a Barry Grant "Mighy Demon" 750 Mech Sec Double Pumper.
He said the difference is nothing short of spectacular.
this is a quote from a post he made about it on another forum right after testing driving the new carb for the first time:
"Now... the long awaited test drive. As soon as I pulled out of my driveway I could tell that something was different. Different in a good way The Vette really pulled as it never has before. I could step down and feel where the secondary open start point was and could control the power..!!! Wow.. What a big difference.
It just feel's completly different from the holly. Even just driving normally...better responce and driveability... No Bog at Full throttel openings...The final test was a Full throttel stomp at a 10 mile an hour roll in first gear.
Holl S_ _ T..!!!!!!!Talk about smoking the tires.....!!! Talk about wheel hop...!!
My 65..never was able to do this...Not that I drive like that... but it now feels like 567Lbs of Torque and 502 HP.. So..Conclusion...
It was the Holly Carb that was the problem......It is Day and Night.. "
the BG he put on is a double pumber but it's also "just" a 750cfm so that would make me think that the Q-Jet may work fine for you.
A friend of mine dropped a ZZ502 in his '65 last year and it came with the Holley carb (or he put on a Holley, don't remember which) that i believe but may be wrong was either a 950 or a 1050. he was never happy with the off idle performance no matter how much he worked to adjust that carb.
Just a few weeks ago he switched out the Holley for a Barry Grant "Mighy Demon" 750 Mech Sec Double Pumper.
He said the difference is nothing short of spectacular.
this is a quote from a post he made about it on another forum right after testing driving the new carb for the first time:
"Now... the long awaited test drive. As soon as I pulled out of my driveway I could tell that something was different. Different in a good way The Vette really pulled as it never has before. I could step down and feel where the secondary open start point was and could control the power..!!! Wow.. What a big difference.
It just feel's completly different from the holly. Even just driving normally...better responce and driveability... No Bog at Full throttel openings...The final test was a Full throttel stomp at a 10 mile an hour roll in first gear.
Holl S_ _ T..!!!!!!!Talk about smoking the tires.....!!! Talk about wheel hop...!!
My 65..never was able to do this...Not that I drive like that... but it now feels like 567Lbs of Torque and 502 HP.. So..Conclusion...
It was the Holly Carb that was the problem......It is Day and Night.. "
the BG he put on is a double pumber but it's also "just" a 750cfm so that would make me think that the Q-Jet may work fine for you.
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
http://www.edelbrock.com/automotive/carb_qjet.html
"Performer RPM Q-Jet, 850 cfm, electric choke ....#1910* "
Apparently that's the only RPM q-jet they made, the 1910. You'll need to find some good metering rods for it, though. It is the M4M design so you'll have to dig around for some K, J, or P rods. Edelbrock only sells the retarded M rods which makes WOT lean as hell.
Considering a 350 only needs 600cfm to run fine, a 502 should be alright with 850cfm.
"Performer RPM Q-Jet, 850 cfm, electric choke ....#1910* "
Apparently that's the only RPM q-jet they made, the 1910. You'll need to find some good metering rods for it, though. It is the M4M design so you'll have to dig around for some K, J, or P rods. Edelbrock only sells the retarded M rods which makes WOT lean as hell.
Considering a 350 only needs 600cfm to run fine, a 502 should be alright with 850cfm.