Single vs dual plane...vs carb size

[F-BIRD'88]

The 6 venturii with just 2 center located primaries
is a very symetric balanced pattern on a 4 bbl intake
with the 2 carbs online..
Simpler...

A six barrel single catb body vrrsion of a qjet would also be
just as oem emissions and fuel econpmy friendly as the qjet.

The primaries of the front carb don't add any value
just complexity and non symetric unbalance.
K.I.S.S. works.

[F-BIRD'88]

To get a symetric balanced pattern with all 8 barrels of 2 qjets
would req turning 1 carb around.. A lot more complex + feul float control problems.

Total length of all 8 barrels requires a longer and taller carb adapter. More pain than gain over the 6 venturii setup.

[F-BIRD'88]

Now there is a much more balanced pattern on a single plane
race intake. Now can add a plenum divider and gain all the benefit of that without the airflow penalty.
1300 cfm... 650 cfm each side with a plenum divider .

[F-BIRD'88]

Much better on a roots street blower than a single carb.
Much bettrr on a blowthru setup (2qjets in a carb box)
than a single 4 bbl carb.

[rfoll]

GM used a half QJ on cars in the late 70s-early 80s. There were several sizes, but the large one was 287 cfm. Throttle response over the previous 2GV was dramatic. Of course, the purpose for them was to improve emissions over the previous 2 bbl. carb. These things are throwaway carbs, making them cheap if you can find them.

[F-BIRD'88]

You'd need 8 of the dual jet 2 bbls to have equal wot air flow
of my 2 qjet 6 venturi setup.

The dual jet 2 bbl flows 226 cfm @3"
Which is 160 cfm @ 1.5" (4bbl carb flow standard)

A lot more complex . I'd rather play with just 4 secondary metering rods and 2 hangers and 2 air valves adjustment
to dial in the 2 qjets.
All done from the top.

[Schurkey]

The dual jet 2 bbl flows 226 cfm @3"
Which is 160 cfm @ 1.5" (4bbl carb flow standard)

There were multiple variations of the Dualjet. I have photos of some of them. I do not have the actual carbs, and my memory is getting...old.

There is the Dualjet 165 (165 cfm???) I believe that this is the "front half of a small-venturi Q-Jet". In this case, it's also the "older" 1974 and previous style casting. If you look closely, you can see "Dualjet 165" cast where the air valves would be on a Q-Jet.


There is the Dualjet 200 (200 cfm???) which--I think--is the front half of the larger-primary Q-Jet.




There is the Dualjet 210 which uses a distinctly-revamped casting. I think it also has the large primaries, but I don't remember it well.




It may be that any of these carbs could have large- or small-primaries depending on application. I found these at my favorite Treasure Yard, and posed them for photos, but I didn't bring them home with me.

[NXBOY]

I found 3mph and two tenth in the eigth mile with a 351w with a RPM and 1 inch spacer by going to a worked 850 anular (choke milled, K/N stub radius short stack about 25
yrs ago. Chevy buddy said my 475 hp SBF couldn't handle it. Anyway I also beleive its hard to over carb with a D/P intake with a decent converter , had 3800 stall. But later found out that with the Torker two it went way Lean from over carbed and this only worked with D/P and a cam with a 110 LSA, didn't gain much I could tell with the 106 LSA with about same Dur. @ .050. But I bet with the RPM and Big Anular it was as fast as a victor jr. and 750 holley That I later went too. 60 ft was awesome with anular and Dual plane and pulled alot harder upstairs with bigger carb. Went around 6.90s in the 1/8 at 3100, Hydraulic flattappet cams 292 cams, Most say they slow down I hear, but some combos go nuts out with them, guess its about keeping carb signal with the small converter. By the way the 750 annual usually does slow down I've always heard. Think the Venturi too small for the Boosters, but it still act like a crutch down low I suspect.