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..

Good stuff, thanks for posting

Mr Shaker, doesn't removing the bigger booster affects the instant throttle response in a negative way?

Not if it's calibrated correctly Mr 76MM.

The regular Qjets do not have extended booster like the factory single ring.

very nice, idea on price when done?

No prices & winter project.

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" ???

I am guessing a sleeve.

no sleeve,
I'm going to machine an extension that will attach to the booster and come to the same length as the HO,

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 !

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.

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

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?

The castings are zinc so welding may do damage.

Very cool project!

Yes I'm liking it!

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

Since Curtis and I both run Q-jets I will be tracking your progress, Jeff. Always something new to learn everyday.

Hey Mike & Gates!
This is a cool project and I've been wanting to do this for about 8 years.
I may run a similar assortment on my 67' GP but that's all stock so outer booster rings will do.

I'm currently machining open & rebuilding the plenum on an old squarebore P4B plenum that I have to also accept QJ.. along with removing exhaust crossover and separate water crossover.... another test mule!

I'll machine out the rings first then come up with a booster design that will fit and secure well.

Damage to the person welding.....