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#1
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Building a one off Qjet
I'm working on a neat project and though I would share some of the build.
I've had a lot of success in the past with my single ring 71' 455HO Qjet that I modified years ago to go along with the current combo in my 71' Trans Am. I had another forum member approach me with a box of parts asking to build something from them which I like to do for his combo. I like the SD-455 Qjet and I'm modeling it after that...like to call it a "Super SD"... Combo is very close to mine, another 455HO with 10.25:1 & nice VooDoo roller. I usually do not mix parts but I think this one off deal will be cool. I'm going to use a 74' Pontiac airhorn & Base with a Buick 800 main body. Also removing outer booster rings and then extend the main booster like my HO to help enhance the reduction in signal strength. The pieces will be recolored and plated and choke will be converted to elec. I'll post some pics..
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Carburetor building & modification services Servicing the Pontiac community over 25 years Last edited by shaker455; 12-16-2018 at 03:24 PM. |
#2
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Good stuff, thanks for posting
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#3
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Mr Shaker, doesn't removing the bigger booster affects the instant throttle response in a negative way?
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#4
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Not if it's calibrated correctly Mr 76MM.
The regular Qjets do not have extended booster like the factory single ring.
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#5
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very nice, idea on price when done?
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#6
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No prices & winter project.
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#7
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Can you elaborate on "extend the main booster" ? I know a 71 HO has no booster outer ring, but what about "extend the main booster" ???
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#8
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I am guessing a sleeve.
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#9
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no sleeve,
I'm going to machine an extension that will attach to the booster and come to the same length as the HO,
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#10
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Oh I did not know the HO had a longer booster. I always thought the only difference was the missing outer ring.
I've had quite a few of those HO carbs over the years and never noticed that. Learn something new every day ! Is that "extension" so to speak supposed to increase the signal ? Can and will you post pics ? That sure will be interesting. Love to see Quadrajet tweaks ! |
#11
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Yes I will post more pics and as I go.
If you look at the HO the inner booster extends about as far as the outer ring on regular units. The extension does not have to be a straight diameter, it can have a taper to it to enhance sheer or venturi effect.
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Carburetor building & modification services Servicing the Pontiac community over 25 years Last edited by shaker455; 12-16-2018 at 07:32 PM. |
#12
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The outer ring works like a shear step on the bottom of a Holley HP downleg booster:
Standard downleg w/taper on left, middle HP downleg, Annular on right An Ebay unit someone cut outer ring from
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Carburetor building & modification services Servicing the Pontiac community over 25 years Last edited by shaker455; 12-16-2018 at 08:52 PM. |
#13
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I may no longer use a Quadrajet but I respect those who do and the results do speak for themselves. I still have in my small track tool box Quadrajet metering rods and an allen wrench for the secondary air flap. Usually a couple times a year the parts or tool gets loaned out.
I agree with Andy it takes time and patience to modify or dial in parts to work in "real" conditions not "copy and paste" theory or internet rhetoric. By real conditions I agree its the street manners first while holding the same et's at the track. Sometime if I'm bored I play around again with a Quadrajet, I do have a bin full of parts and carbs and a few intakes. To date my best recorded et/mpg combination is 10.81/126.70 and 15.75mpg on the same day. Not bad for a basically stock Holley.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#14
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Jeff have you ever tried welding on these castings?
I'm just curious how it would work, never had time to try it. Possibly silver brazing would be better? Or maybe tig brazing with silbronze? |
#15
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The castings are zinc so welding may do damage.
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#16
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Damage to the person welding.....
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#17
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Very cool project!
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#18
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Yes I'm liking it!
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Carburetor building & modification services Servicing the Pontiac community over 25 years |
#19
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i'm anxious to see how this turns out and photos along the way!! !i enjoy seeing the Q-Jet Mods and am very grateful for members showing us and sharing some of their secrets...Thanks Jeff
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#20
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Since Curtis and I both run Q-jets I will be tracking your progress, Jeff. Always something new to learn everyday.
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69 Bird w/1970 400 block(409 cubes), #64 heads, hyd. roller, Q-jet by Jeff E., original interior, ps, pdb, th350, and 3.73 gears. Pump gas, street driven muscle. 3800 lbs. race weight. Best, 11.39 @118, my son's car. 79 T/A w/463, Scat crank, Eagle rods, Icon pistons, Lunati solid roller, 262/270, KRE 325 heads, Northwind intake, QF950 carb, full interior, ps, pdb, th350, and 3.73 gears. Pump gas, 3650 lbs. race weight. 10.68 @ 126 so far... no tuning yet. |
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