Holley 6212 AAA 800 cfm Spreadbore
April 15th, 2018, 06:16 PM
#1
Registered User
Thread Starter
Join Date: May 2014
Location: Swanton, Ohio
Posts: 124
Holley 6212 AAA 800 cfm Spreadbore
I was thinking about shopping for 1 to try out. I know that they are no longer making it so I would be looking for NOS or used. Has anyone used it before? So that I may learn from your experience before going down this route.
Thank You ahead of time.
Thank You ahead of time.
April 16th, 2018, 08:17 AM
#3
Registered User
Join Date: Aug 2013
Location: Evansville, IN
Posts: 10,261
My old man had a spreadbore Holley on his 71 Corvette with stock 350.
It did a couple things differently.
The Holley would not let fuel evaporate so much, and the QJ required more cranking when sitting for a while.
The QJet did not load up while idling which the Holley did.
The Holley had mechanical secondaries and you would feel the boot of the gods when they kicked in; the Qjet was more smooth.
The Holley would let the car do 135 all out, and the QJet allowed 125, circa when new, 1972.
It did a couple things differently.
The Holley would not let fuel evaporate so much, and the QJ required more cranking when sitting for a while.
The QJet did not load up while idling which the Holley did.
The Holley had mechanical secondaries and you would feel the boot of the gods when they kicked in; the Qjet was more smooth.
The Holley would let the car do 135 all out, and the QJet allowed 125, circa when new, 1972.
April 16th, 2018, 08:25 AM
#4
Registered User
Join Date: Oct 2017
Location: Connecticut
Posts: 82
April 16th, 2018, 10:19 AM
#5
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,265
April 16th, 2018, 10:46 AM
#6
Registered User
Join Date: Aug 2013
Location: Evansville, IN
Posts: 10,261
I wasn't precise enough. The Holley did not have the vacuum air horn valves the QJet has. Mechanical secondaries, in my terms, means the whole back two barrels, not just the throttle blades.
April 16th, 2018, 10:50 AM
#7
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,265
The Qjet has mechanically operated secondary throttle plates, period. The air valves obviously open in response to mass air flow through the secondaries, but they can be adjusted to preclude any added resistance. If properly adjusted, this will not be a performance loss.
April 17th, 2018, 05:55 AM
#9
Registered User
Thread Starter
Join Date: May 2014
Location: Swanton, Ohio
Posts: 124
I was thinking of using it on our W-30 so that I wouldn't have to alter the factory carb. Our car currently has the Sig Erson Hy Flow2 cam in it with the stock intake. Not really wanting to change the intake. I have use the Holley 650cfm Spreadbore in the past and really like it. That is why I was thinking of the 800cfm on the stock intake.
April 17th, 2018, 12:40 PM
#12
Registered User
Join Date: Aug 2013
Location: Evansville, IN
Posts: 10,261
The Qjet has mechanically operated secondary throttle plates, period. The air valves obviously open in response to mass air flow through the secondaries, but they can be adjusted to preclude any added resistance. If properly adjusted, this will not be a performance loss.
April 17th, 2018, 03:53 PM
#14
Registered User
Join Date: Apr 2018
Location: Cobleskill NY 12043
Posts: 83
I agree with Old Cutlass,if prepared by someone who understands Q-jets and knows their faults,they are an awesome and trouble free carb.However the Holley spread bore is also an awesome carb,I have built many with never a problem.I have three in service in my own vehicles right now.When building a Holley you must be surgically clean as they will tolerate ZERO foreign material.If you choose to go that route,I have several of them if interested
April 18th, 2018, 04:34 PM
#15
Registered User
Thread Starter
Join Date: May 2014
Location: Swanton, Ohio
Posts: 124
While that Carb on Ebay looks temping, I don't like working with Ebay and do not have the means to do so.
When you say several, what kind of shape and condition are we talking about? PM me if you would like to keep personal information safe.
April 19th, 2018, 03:01 AM
#16
Registered User
Join Date: Nov 2015
Location: So. Ca.
Posts: 651
A major thing to consider is that Quadrajets were federal emission carburetors so they had precise idle and cruise fuel metering. Off the shelf Holleys could dump as much gas as they wanted and worked better on modified engines. Quadrajet idle/cruise circuits can me modified for high performance engines and give great throttle response. Check out this video as proof.
April 19th, 2018, 06:37 PM
#17
Registered User
Join Date: Jan 2018
Posts: 400
A major thing to consider is that Quadrajets were federal emission carburetors so they had precise idle and cruise fuel metering. Off the shelf Holleys could dump as much gas as they wanted and worked better on modified engines. Quadrajet idle/cruise circuits can me modified for high performance engines and give great throttle response. Check out this video as proof.
https://www.youtube.com/watch?v=nyyRoaeujiA
https://www.youtube.com/watch?v=nyyRoaeujiA
April 20th, 2018, 05:43 AM
#18
Registered User
Join Date: Apr 2018
Location: Cobleskill NY 12043
Posts: 83
Holley spreadbore
I looked & don't have a 6212.I do have 6211's & 6213's,both are 800 cfm and have divorced choke.I also have a 6910 which has manual choke & is 800 cfm.$175 plus ship.If stiil interested I'll send you pics of what you choose.I will disassemble to check for any issues.oxidation or incorrect parts.I will quarantee you a good rebuildable core carb.If you're not in a hurry I could build it for you,but right now I'm swamped doing rears and muncies.Dennis
Thread
Thread Starter
Forum
Replies
Last Post
