Shark Racer

In person, not on the internet.

They have a high-rise and 2 low-rise variants. (5603, 5610, 5745)

Anyone ever see one of these unicorns in action? I can't imagine it would be very easy to get this setup running right... I guess you could say you set up a quadrajet with four corner idle at that point? (just not 8. )

If I had $$, time, and a spare vehicle or even an engine on a run-stand, I'd consider giving this a shot just to see what happens.

7T1vette

Who has an engine that requires 1500 cfm air/fuel?

And, if it's just for "bling", 3x2 system is more attractive than 2 Q-jets on one manifold.

Finally: With a spread-bore layout, how to you 'equalize' the air/fuel flow with 2 Q-jets? Any way you arrange them on the manifold, you have areas that will not get adequate flow and others that will get too much.

As much as I like the Q-jet as a single carburetor system, I think two of them on one manifold is NOT a good idea.

Shark Racer

All questions I wouldn't want to pioneer the answer to... and I agree with you.

But the parts exist... someone somewhere must have done it. At the very least, at Offy.

oldalaskaman

common back in the day, you could set them up progressive or all in, you still see them on craigs, pretty cheaply priced compared to what they were new. some of the ads claim they were oe on early vettes
more popular was the big afb's. easier to get to run together
http://cgi.ebay.com/ebaymotors/Offen...item257650b726

7t9l82

some of the 409 racers tried them years ago, and weren't successful. they fell out of favor quickly. different but not really cool in my opinion

Shark Racer

Yeah.. like I said, I think it would be an uphill battle, but still interesting. I'd give it a shot if I had the resources.

oldalaskaman

I ran a dual quad on a 440 dodge back in the day, it was fun but even back then with gas at .38 per gal. it was like standing on the hood with a gas hose. it was good for wot but anything else you were better with a 4 bbl

Mod75

Oh yes, 409 and dual carters, what a mess, awesome too look at but a pain. Had a 348 and dual carters in a 56 rag top. Not knowing that it was too much and expecting it to be better was the first downfall.

7T1vette

A dual-quad setup with two, small capacity square-bore carbs would make sense. A dual-quad setup with Q-jets doesn't. At least, it doesn't make sense to me.

oldalaskaman

it didnt make sense back then either , but it was fun

bpassmore

Can I raise my hand?
Dual Q Jets would be a challenge, but they have a lot of tuneability built in. The air valve could be used to size them to the system. I kinda like the 2X4 set up, been fooling with them since the early 60’s with the WCFBs, the 409 /w the smaller AFB did run pretty good , I have run the 409 AFBs on the factory SB 2X4 manifold with adaptors.
My avatar, a ’55 Chevy has a set of Edelbrock 650's on an original Corvette 2X4 manifold with port matched adaptors; it was a problem to balance the air valve so it would not bog (hesitate). Does it run great? No, but it pulls pretty darn good. Engine, 355, 10.5 cr, 1.94 , 1.6.valves. A lot of torque! The power plays out a little over 5500 or so rpm.

Just finished a 70 Chevelle,440 with 2X4 Edelbrock set with dart Pro II heads, Roller cam and rockers, 3000 stall with TH 400 and 4.10 12 bolt. Haven’t had a chance to take it to the strip. Feels good though.

TimAT

The PO had installed a 2x4 Edelbrock (C66-R) and a pair of their carbs (I think it's the setup Jeg's sells). Ran great until he let it set full of the crap gas and some whizz-bang octane booster he used. Turned everything in the carbs green and crusty, and stuck the floats. Got them all cleaned out, but haven't gotten around to putting them back on.

I can say it ran like a turpentined cat. Good idle, and pulled like a train. Even when it was new in '69 with the 3x2's it wasn't really easy on the gas.

MotorHead

They used to be the catz azz but they are dinosaurs now, you wouldn't want to put one on for performance, maybe get it polished for car shows.

Indiancreek

I've been thinking about trying one on a 434 I'm buliding for my 75. Thinking of trying a couple 650 holley carbs on it. Not for perfomance so much as the look.

langg

I've been running the C-66-R with 2 Edelbrock 1406's on my 540 for a couple of years now. Not using progressive linkage. Once I got the jets/rods pretty close, no hesitation no bog. I like the look. I even made up an air box floor that attaches to the carbs and seals to the bottom of my L88 style hood for an outside-air intake.

LangG

7t9l82

the o.p was talking about a dual QUADRAJET carburetor intake.

vetteman64

I have this idea on my bucket list, a different look even if it won't run well. A few years back, a seller at Corvettes @ Carlisle had this Offenhauser manifold. I hesitated and when I came back it was sold. Still looking to buy one.
On a related note, my 69 Camaro had a spreadbore Holley when I purchased it. Maybe 2 of these could be made to run better on the manifold vs 2 Quadrajets.
C Ya, Joseph Rock
Frankenstein 59 & Grand Sport proto

dochorsepower

And who can forget the Beach Boys with:
"4 speed, dual quad, posi-traction, 409"

7t9l82

Dual holley spread bores won't fit on a dual Quadra jet intake.
Not to rain on your parade but that intake was a stupid design back when it was made and it hasn't gotten any better,the fuel distribution was terrible. There are better dual quad and 3x2 setups today that with a good set of heads will work pretty well. Stupid guys want g to be cool back in the day would bolt that stuff on and the car ran like garbage. The smart guys would have a built motor with a bigger cam ported heads and higher compression could make some of that stuff work.my thought on that intake, be glad it was gone.

Shark Racer

At this point I'd be happy to see a picture, more curiosity than anything.

I'd need a lot more $$, spare time and space if I wanted to take that project on...