dual quad small blocks?

[340six]

Man I see what I started! irat:

I ended up with a polished air gap and an 800 avs and well jet and rod it as needed. I kind of would of liked two 500s sitting on a dual quad, providing the plenum, runners etc were tuned good as well. Am am sure I should still make decent power on the 416. I used to have an old offy 273 dual quad, sold it, and it would not have been the hot setup on a 340 set of heads anyway.

Yep I wanted the cool factor, but performance too. And while I love the look of the 6 pack ouch pricey! And one 4 is easier to tune too.

I have an addiction to intakes and other things I can polish. I even got intakes and parts for engines I don't own.

 

[str12-340]

inline dual quads:
offy version is a single plane with VERY SHORT RUNNERS. I think this is why they have never really caught on, especially on a street car. The Edelbrock D-64 and D-66 are dual plane dual quad manifolds and they seem to work better especially on a street car. I'm putting together a D-66 with progressive 500 AVS2s.

Below is my STR-12 with Eddy 500 AFBs. I have been running it on the street for over 15 years (maybe 20,000 miles). About 15mpg. a blast to drive!!! I have learned a lot about these over time and am willing to share info for anyone who actually has one that they want to use. First lesson is installing the modifications in the Direct Connection Engine book, which deals with fuel puddling in the plenum leading to backfires.

Never use the single 4 or 6 pack STRs (only available for big blocks) A quick look at the inside of the of the manifold shows why - The cross ram carbs sit over the end of the long runners where the others sit in the middle with the ports facing away from the carbs.

AMC proponents got enough prepaid advanced sales and Edelbrock made a run of the STR manifolds for them several years ago. I haven't seen an STR 12 for $1200 in 10 years. Here's what I found at Mopar Nats last year.

 

[str12-340]

The D-64 & 66 are small port manifolds. To seal well, the top of the ports at the head should be built up and the port mouth reshaped.
I'd certainly buy a new big port dual quad Edelbrock if they made one.

 

[Michael Harrington]

The D-64 & 66 are small port manifolds. To seal well, the top of the ports at the head should be built up and the port mouth reshaped.
I'd certainly buy a new big port dual quad Edelbrock if they made one.

Exactly. Place an LA 340/360 intake gasket on one of those Offenhauser dual quad manifolds and you'll see why they cannot be bolted to the 340/360 head and actually seal. The SB 340/360 671 Blower kits used a modified dual quad Offy with welded up port areas. The welding added material and thus allowed them to enlarge the port to 340 size. A dual carbureter non tunnel ram intake manifold was never made for the 340/360 head. You can currently get an Indy Mod Man. But as a dual quad manifold its not a good street intake- but it looks great.

 

[Brooks James]

Accidentally reposted prior info

 

[Brooks James]

D64engine 64-65 273

Carter AFB 2992's 1960 Poly
318. 500 cfm

Edelbrock 5698

Now $826 at summit , not available

 

[Brooks James]

The D-64 & 66 are small port manifolds. To seal well, the top of the ports at the head should be built up and the port mouth reshaped.
I'd certainly buy a new big port dual quad Edelbrock if they made one.

Thanks for the mod tips

 

[65rbdodge]

New offy intake with crossram adapters, 2 500 edelbrocks on a 408/4speed in my 47 desoto. Tuned them with an AFR gauge, it runs pretty good

 

[4spdragtop]

I bought an NOS offy DQ that I messed with for a bit on the 273. I thought it may be good for the 340. NOPE! I laid 340 intake gaskets down and mocked up. Only way to use it on x heads would've been to build up the mentioned areas. Which if you're paying someone....
I posted pics of 340 gaskets on the intake here somewhere....

The D-64 & 66 are small port manifolds. To seal well, the top of the ports at the head should be built up and the port mouth reshaped.
I'd certainly buy a new big port dual quad Edelbrock if they made one.

Exactly. Place an LA 340/360 intake gasket on one of those Offenhauser dual quad manifolds and you'll see why they cannot be bolted to the 340/360 head and actually seal. The SB 340/360 671 Blower kits used a modified dual quad Offy with welded up port areas. The welding added material and thus allowed them to enlarge the port to 340 size. A dual carbureter non tunnel ram intake manifold was never made for the 340/360 head. You can currently get an Indy Mod Man. But as a dual quad manifold its not a good street intake- but it looks great.

 

[rumblefish360]

Exactly. Place an LA 340/360 intake gasket on one of those Offenhauser dual quad manifolds and you'll see why they cannot be bolted to the 340/360 head and actually seal. The SB 340/360 671 Blower kits used a modified dual quad Offy with welded up port areas. The welding added material and thus allowed them to enlarge the port to 340 size. A dual carbureter non tunnel ram intake manifold was never made for the 340/360 head. You can currently get an Indy Mod Man. But as a dual quad manifold its not a good street intake- but it looks great.

Not true, you had to spec it through Offenhauser.

 

[rumblefish360]

And now that we are showing stuff off….
LMAO!

 

[Michael Harrington]

Not true, you had to spec it through Offenhauser.

Exactly. The companies bought Offenhauser manifolds and modded them to work as blower manifolds. Even with other brands- I saw an Oldsmobile with a converted Offy and a 671 blower.

 

[Michael Harrington]

When I replaced the intake manifold gaskets on my 95 318 Magnum I set down 2 old school intakes before I reinstalled the kegger. I eventually will switch the OBD1 tech to dual carburetors. I will use the Offenhauser low profile. My heads will be recent Chinese EQ heads that I ported that have the LA intake bolt arrangement. The Magnum head intake port window is smaller than on an LA head. I believe my 273 Offy will seal because of the Magnums smaller port windows. Im thinking of making my own paper intake gaskets- to go between the head ports and the manifold ports. The overall dimension of the gaskets would be 318 magnum- but the intake ports of the gasket would be 273 size. Best chance at a reliable seal IMO. Probably utilize the stock short block and go with mentioned heads and a mild roller cam with dur around [email protected]. Goal would be just a nice-looking good running punchy 318 Magnum in my mini tubbed Dakota Sport.