Offy 2x4 Q-Jet intake?

[pdq67]

Anybody have one or have used one?

How'd you like it?

pdq67

[F-BIRD'88]

Cannot help you with that , but if I wanted to use 2 qjets, I'd mount them back to back on a 2x4 carb adapter on a capable
single 4 bbl intake. The 4 big secondaries would be right over the
plenum in a symeterical pattern.

The 4 outer small primaries would also be symeteric
and provide smooth responsive idle and low speed part throttle.

The progressive yet symetic 4 central secondaries would really
hit it at WOT yet tunable air door progression.

Throttle linkage for back to back c2x4 qjet arb mounting is not really that
complicated.

[shiftbyear]

I've seen the offy for a Pontiac they're inline not back to back. Olds tried a crossram version. I've also seen a 4 qjet olds attempt but I don't think they got all the bugs worked out. 1400-1500cfm is a lot to manage on a dual qjet setup. Let us know how it works out. Good luck.

[mag2555]

I picked up a Offy 360 equa flow back in 78 for my blown Pontiac 455 .
My Blower set up was from Dyers and used a Offy single 4 Manifold adapted under the Blower.
I was going to have Dyers mod the 2 4 bbl Manifold , but I never got around to it, nor using the Manifold just as it was on my other cars as I thought that the very short runners would kill my bottom and mid range TQ!

[novadude]

Is that Olds intake above a factory experimental piece or aftermarket?

[mag2555]

Even that 2 Q -jet Carb Manifold has no balance tube section between Plenums and would likely run like crap when the motor is not up to the rpm that the Manifold is tuned for.

[Barry Burch]

I tuned my nephews 360 offy manifold carb setup
for his 330 olds back in the 70's. The secret is to run
a 4 corner idle and 1 to 1 linkage.
good drivability and power then. Otherwise its a slug.














i

[mag2555]

So what your saying is that if it was a single 4 bbl you would always be deep into the throttle due to the Manifolds 3 inch long runners and big common Plenum .

[engineguyBill]

Anybody have one or have used one?

How'd you like it?

pdq67

Tried these manifolds back in the 70's, but it seems like the standard 2 x 4 square bore manifold with Carter AFB's ran much better.

[magicrat56]

I've been running one for the last few years. using twin 780's which I had to play with for awhile but believe it or not i'm back to stock settings.Basicly these old intakes were actually blower intakes with carb pads added on fully-divided single planes. I SURE that the new eddy's being dual-planes would be the better choice but you cant look like twin Holleys.If I can add this I only run the linkage as progressive going to direct 1to1 really makes low speed driving tough.As far as twin Q-JETS I would do it in a heart beat! You would have to have identical carbs built but you'll love it.

[F-BIRD'88]

That Olds V8 CrossRam intake manifold would have been a lot better cross ram if it had used 4 Qjet carbs oriented like this on the plenums, instead of 2 Qjets.

Symetric venturii locations directly near each intake runner entrance with the small primary
venturii infront of the runners port opening for good fuel distribution at idle and part throttle.

The 4 Air valve controlled secondaries allow air flow and sec throttle rate progression
control and fuel flow metering control with metering rods.
The 4 Qjets will not be too much carb cfm. The 2 Qjets on each bank, primary throttles
could be ganged together as the total 4 primary throttle area is still small.
At WOT the engine will take as much of the 4 x4 (16) venturi air flowcapacity as it needs,
Without over carbonation by the nature of the adjustable secondary throttle and sec air valve opening rate and sec metering rod rate and size select ability.
Most of the "tuning" is all about dialing in the secondary sides ( secondary metering rods and hangers and air door opening spring rate of the 4 Qjet carbs. Much like dialing in a Single qJET. If the engine is built powerful ( big valves, big high flow intake and ex ports, high compression ratio and big tuned exhaust headers and correct camshaft valve events) it will a good use of the air flow capability of the 4 Qjets with very good idle/part throttle and WOT fuel metering by their orientation on the 2 Plenum's.
Much better than 2 4bbl carbs Qjet or not. High power capacity with good "drivability".
The 4 small primarys with symmetric venturi orientation are a Big + for "streetability/Drivability"

Too bad these Cross-Rams were not cast with removable- bolt on top carb plates.
There is nothing stopping a hot rodders from cutting the tops off and adding a flange top to allow bolt on plenum tops.
Imagine that 4 Qjet crossram induction on a big block Olds V8 SkiBoat or JetDrive boat.
It would "Howl"//

For all the same above reasons and benefits and advantages 4 Edelbrock /Carter AFB or AVS 4bbl carbs would rock too.

[dwilliams]

Who made that thing?!!

Are those square or spread bore flanges under the tape?

[engineguyBill]

I think that is the 2 x 4 manifold, shown in a previous post with four Q-jet adapters set in place to illustrate the concept. Am thinking that this is probably a Batten designed manifold, as he did much research and development on Olds engines back in the day.

[dwilliams]

Ah. Okay. Had me going there for a bit.

BTW, if someone wanted to build some little stub manifolds, the port spacing between Olds heads and Ford 351W throttle bodies is almost identical...

[quickd100]

They should work great once dialed in. I run a Weiand tunnel ram with 2 Carter 850 thermoquads. With the small heads the motor made 853hp and 818 ftlbs. I could also squeak out 10 mpg IF I drove it nice. The motor is a torque monster, 765 ftlbs@ 3500rpm.