j par
Well-hung Member
A carburetor atomizes fuel and makes a mixture and the cylinders draw that mixture in whether it's from a short distance or a long distance... They are each going to fill its need with an itemized mixture....
Dual quad info
- Thread starter 4spdragtop
- Start date
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Can't argue with you as I've never tried it. Hey, sometimes stuff just works, even if you think ot shouldn't!
MomsDuster
Well-Known Member
Assuming a shared plenum?
j par
Well-hung Member
No kidding Sherlock Holmes...
Can you show me an example of one that is not shared?...
One of my friends bought a refurbished Eddy at Oreilly a few years back. It was cheap.
MomsDuster
Well-Known Member
Ok wise ***, in a tunnel ram yes shared plenum. But some dual quad intakes are dual plane correct? I’m no expert, don’t claim to be either, just my understanding. On a side note i’m curious as to why on single four barrel tunnel rams, the carb is mounted in the middle? Better fuel distribution, aesthetics?
j par
Well-hung Member
LOL this is why I don't post very much anymore LOL and why I told the Op in a PM that I would rather have phone call than discuss this on the forum.. while there's a lot of knowledge out here there's a lot of repeated miths and hearsays ..
What about the cross ram?...
Every time I see a single four-barrel tunnel ram I think to myself WHY!!??... And if the four barrel was pushed to the front or the back I'd completely lose my mind... I would be under bad aesthetics overload... LOL..
Isolating one side of the other is not the same as isolating front to back. The carburetor will still run the entire engine just one side from the other not nothing going to the front if the carburetor is not on the back and a plate was placed over the top front carburetor which no one will do... You're still getting some air and fuel from the idle circuit of the front carburetor let alone when it's really pulling and opening up the back and secondaries...
Anyways I think I'm done here trying to mythbust...
If anybody's interested in my 10 plus years of tunneland experienced I'll talk to you on the phone..
MomsDuster
Well-Known Member
LOL! And this is why I don’t like asking questions on the open forum! 
In all seriousness, thanks for the open and honest response.
In all seriousness, thanks for the open and honest response.
j par
Well-hung Member
This is the dual quad linkage I'm using. I noticed here on summit it's out of stock... Remember being a little cheaper than that but maybe not it's been 10 years...
Ok getting back to the DQ while still moving fwd on the Restart the rebuild thread.
I figured I may as well test the DQ on the 273. With the huge port mismatch to the xheads, this intake wont go on the 340. So 273 it is.
I decided to give it a gentle clean up with burrs and rolls. Got rid of a decent amount of flash.
Also got felpro 1243 gaskets, no way in hell 1213 would work.
Black marker on ports is 1213's, orange is 1243.
Lucky this has coil stand too. The 6pack style from the LD4B wouldn't fit.
I was using Edelbrock spacer 9266, not sure if I'll use them or not. More surface area on intake would mean cooler?
Hit the hardware store tomorrow for heim joints and 5/16 threaded rod.
LD4B is being a ***** to remove with the RTV on rear China wall lol.
Anyone run stock style throttle cable? Have lots of mocking up to do.
I can see this is gonna domino lol.
Before tearing apart I fired her up to make sure fuel/ Eddy carb was good. Then removed Eddy and installed orig Carter to make sure it was half *** tuned in lol. So 2 running carbs. I'll run a choke on rear carb as it will be primary carb.
Hope to be able to set up progressive.
Thanks
Steve
I figured I may as well test the DQ on the 273. With the huge port mismatch to the xheads, this intake wont go on the 340. So 273 it is.
I decided to give it a gentle clean up with burrs and rolls. Got rid of a decent amount of flash.
Also got felpro 1243 gaskets, no way in hell 1213 would work.
Black marker on ports is 1213's, orange is 1243.
Lucky this has coil stand too. The 6pack style from the LD4B wouldn't fit.
I was using Edelbrock spacer 9266, not sure if I'll use them or not. More surface area on intake would mean cooler?
Hit the hardware store tomorrow for heim joints and 5/16 threaded rod.
LD4B is being a ***** to remove with the RTV on rear China wall lol.
Anyone run stock style throttle cable? Have lots of mocking up to do.
I can see this is gonna domino lol.
Before tearing apart I fired her up to make sure fuel/ Eddy carb was good. Then removed Eddy and installed orig Carter to make sure it was half *** tuned in lol. So 2 running carbs. I'll run a choke on rear carb as it will be primary carb.
Hope to be able to set up progressive.
Thanks
Steve
NoCar340
The Original Partstitute
A friend has dual quads on the 318 in his '68 Coronet 440 sedan--yep, a 4-door--with a bolt-action 3-speed. 100% stock except the intake, right down to the single exhaust. It's a total cobblef__k: home-grown 1:1 linkage with an Edelbrock AFB up front and a 340 AVS on the back. He literally put it together with crap he had lying around. And it works... surprisingly well, in fact. It never stumbles or hiccups. When he stabs it, it's right now. Obviously the car's no rocket, but it's considerably more fun than it was with the two-barrel.
It's also a blast to see the confused looks on people's faces while they try to process a very-original '68 four-door with a three-on-the-tree and dual freakin' quads.
It's also a blast to see the confused looks on people's faces while they try to process a very-original '68 four-door with a three-on-the-tree and dual freakin' quads.
That's an Offenhauser...
I dont think there is port misalignment?
I dont believe it was ever intended for big valve/port heads? I dunno, but when I saw the potential problem using it on the xheads I said screw it I'll put it on the 273.
I dont believe it was ever intended for big valve/port heads? I dunno, but when I saw the potential problem using it on the xheads I said screw it I'll put it on the 273.
Took a bit to open up to match the Edelbrock heads used a long tip to get up into the tubes mate just bought the new stock Offy fits like crap looks like its made in China bolts are way off also poor fit on the heads
I would suggest that you try to set the carbs up to open progressive and use the back carb as primary. That way during the 80% of the time that you are just running on primaries on the primary carb, your "2 barrel" is in the middle of the manifold next to the cross over, not all the way in the front of the manifold.
The secondaries on the super sniper do not move until you are over half throttle ,the way holley has set up the dual quad is that the front & rear body jets are in parallel & even if you stop 1 set of primaries opening until later the injectors on the other body will still fire .
autopar3000
Well-Known Member
Maybe the FABO engine gurus can answer this question... if the cylinder head ports are larger than the intake manifold ports, like is showing in Steve's post #60 in this thread, is it really that big of a deal?
I mean, obviously having the intake and head ports match would be better, but with the fuel / air mixture being drawn into the cylinder head's larger intake port it's not like the mixture is running into anything. I can see how a large intake port and small head port would be terrible, but when it's like this situation is it really that bad?
I mean, obviously having the intake and head ports match would be better, but with the fuel / air mixture being drawn into the cylinder head's larger intake port it's not like the mixture is running into anything. I can see how a large intake port and small head port would be terrible, but when it's like this situation is it really that bad?
Makes complete sense. No luck with heims locally, so ordered 2 from Amazon. Christ HD didnt even have threaded rod 5/16-24.
Digging thru extra goodies I found the threaded end for kick down. May come in useful.
Gotta mount choke to mock up dual fuel inlet.
Digging thru extra goodies I found the threaded end for kick down. May come in useful.
Gotta mount choke to mock up dual fuel inlet.
It wasnt so much the mismatch between xheads and DQ, it's that going to felpro 1213 gaskets(for x heads). There is not enough area on roof of DQ ports for good sealing. Custom gaskets or build up the sealing flange?
Post #70.
I think it is a benefit to have the intake port openings slightly smaller. Helps prevent reversion & mismatch the other way, which would be detrimental.
I remember when Edel first released the Tarantula single plane intakes, the instruction sheet said NOT to enlarge the port openings.
I think it is a benefit to have the intake port openings slightly smaller. Helps prevent reversion & mismatch the other way, which would be detrimental.
I remember when Edel first released the Tarantula single plane intakes, the instruction sheet said NOT to enlarge the port openings.
Spent a bit of time, not much. Bought 5/16 stock rod and fine threaded it myself. A couple bolts in the spare kickdown piece and threaded rod. Hoping for heim joints soon.
Throttle return springs mocked. I'll need some different sized springs.
Need dual fuel inlets, air cleaners, hole to hole is 6 3/4" on air breather holes.
Throttle return springs mocked. I'll need some different sized springs.
Need dual fuel inlets, air cleaners, hole to hole is 6 3/4" on air breather holes.
I found these air cleaners from Speedway (and other sources) for the in-line DQ set up that I'm working on.
www.speedwaymotors.com
They have them for the early smaller throat carbs too.
Speedway Round V8 Logo Dual Quad Air Cleaners, 5-1/8 Inch Base
These air cleaners are brand new reproductions of a classic air cleaner featuring the iconic V8 logo. For dual quad carburetors. Comes with a modern air filter. Compatible with 4-barrel carburetors with a 5-1/8" neck.
They have them for the early smaller throat carbs too.
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