Interesting air cleaner on this 273 Dual Quad

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Michael Harrington

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Neat set up. Edelbrock D64 manifold. Looks like a factory Hemi air cleaner assembly?

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Kinda makes the whole thing worthless in both function and value.
 
On my mini tubbed Dakota I recently did the intake manifold plenum plate re seal. While the keg was removed I set my Offenhauser dual quad on the 5.2 as well as a Weiand Tunnel Ram. The 273/318 Offy probably will work great with OEM Magnum heads. The Magnum heads have smaller intake ports than the LA340/360. The intakes designed for a 273 don't have enough cast in meat to seal appropriately on the LA 340 port.In fact when the Roots Blower manufacturers would convert Offy intakes into LA blower manifolds they first welded up the flanges and partial port to build up and have sufficient material to seal.

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I bought same NOS dual quad thinking I could use on my 340 build(x heads)....not a chance lol. Like you said the outside of the flange vs the port, you could see daylight lol. So it went on 273 for a short stint lol.
I love the looks of them.
Intake gasket is Felpro 1243 273/318 size. Orange marker 273, pen mark 340.
Michael Harrington said:
On my mini tubbed Dakota I recently did the intake manifold plenum plate re seal. While the keg was removed I set my Offenhauser dual quad on the 5.2 as well as a Weiand Tunnel Ram. The 273/318 Offy probably will work great with OEM Magnum heads. The Magnum heads have smaller intake ports than the LA340/360. The intakes designed for a 273 don't have enough cast in meat to seal appropriately on the LA 340 port.In fact when the Roots Blower manufacturers would convert Offy intakes into LA blower manifolds they first welded up the flanges and partial port to build up and have sufficient material to seal.

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4spdragtop that is a great looking 273.​

The oOffy and probably the Edelbrock dual quad manifolds were specifically made for the 273 only. When the 318 came along it worked on those because the heads were the same. But no one tooled up and made a low profile under hood dual quad for the LA340 when it came out. Thats a shame. A dual quad airgap for the 340/360 heads would be awesome. I passed on the Modman. With its dual quad top, it looks wonderful. But really, it's a cavernous vast wide-open plenum manifold best suited as a blower manifold. Bolting on the dual 4 top looks great but from what I read not good on a moderate performing street engine.
 
Thanks, I got tired of messing with the Offy as I was trying to get 340 built. And get to Moparfest which i missed lol. So I pulled it off the 273 and shelved the setup for now. Once 340 is installed I'm hoping to put commando pistons in 273 and then take a stab at dq again. They just look so cool.
So did you have your dq drilled for magnum heads?
Michael Harrington said:

4spdragtop that is a great looking 273.​

The oOffy and probably the Edelbrock dual quad manifolds were specifically made for the 273 only. When the 318 came along it worked on those because the heads were the same. But no one tooled up and made a low profile under hood dual quad for the LA340 when it came out. Thats a shame. A dual quad airgap for the 340/360 heads would be awesome. I passed on the Modman. With its dual quad top, it looks wonderful. But really, it's a cavernous vast wide-open plenum manifold best suited as a blower manifold. Bolting on the dual 4 top looks great but from what I read not good on a moderate performing street engine.
Click to expand...
 
4spdragtop said:
I bought same NOS dual quad thinking I could use on my 340 build(x heads)....not a chance lol. Like you said the outside of the flange vs the port, you could see daylight lol. So it went on 273 for a short stint lol.
I love the looks of them.
Intake gasket is Felpro 1213, 340 size.


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I'm not real familiar with small blocks.
Are those port pictures right side up, or upside down?
in other words, are the 340/360 ports taller than 273/318, and slightly wider??
I have a tm7 440 manifold that has had a slug of aluminum added to the top of the port, to work on a max wedge head. Top of the port with added material is fine, bottom of the port, the manifold is razor thin.
 
Pics are upside down. Gasket is a felpro 1213, orange marker is Felpro 1243(273/318). I had it sitting on xheads, no way it would work without welding/building up the flange. Doable, just not by me lol.
33IMP said:
I'm not real familiar with small blocks.
Are those port pictures right side up, or upside down?
in other words, are the 340/360 ports taller than 273/318, and slightly wider??
I have a tm7 440 manifold that has had a slug of aluminum added to the top of the port, to work on a max wedge head. Top of the port with added material is fine, bottom of the port, the manifold is razor thin.
Click to expand...
 
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My bad, that is actually a Felpro1243, shown in pic, but the pen marks shown show where the 1213 340 ports were marked. I will edit above post.
Michael Harrington said:

4spdragtop that is a great looking 273.​

The oOffy and probably the Edelbrock dual quad manifolds were specifically made for the 273 only. When the 318 came along it worked on those because the heads were the same. But no one tooled up and made a low profile under hood dual quad for the LA340 when it came out. Thats a shame. A dual quad airgap for the 340/360 heads would be awesome. I passed on the Modman. With its dual quad top, it looks wonderful. But really, it's a cavernous vast wide-open plenum manifold best suited as a blower manifold. Bolting on the dual 4 top looks great but from what I read not good on a moderate performing street engine.
Click to expand...

33IMP said:
I'm not real familiar with small blocks.
Are those port pictures right side up, or upside down?
in other words, are the 340/360 ports taller than 273/318, and slightly wider??
I have a tm7 440 manifold that has had a slug of aluminum added to the top of the port, to work on a max wedge head. Top of the port with added material is fine, bottom of the port, the manifold is razor thin.
Click to expand...
 

4spdragtop asked: "So did you have your dual quad manifold drilled for magnum heads?"
I have a new set of EQ Magnum heads that are drilled for LA intake manifolds. In the future- I will build a carbureted 360 to replace the OBD1 318 that's in the truck currently and the 360 will use the EQ heads. Modern EQ heads are not the same as they were 10 years ago- they currently are not a performance improvement over stock Magnum heads. I was fully aware of this, and I am cleaning up and mildly porting the Chinese cast EQ heads I have. FYI these EQ heads I bought from Vegas parts and cores were checked out by a local machine shop. Everything checked out great. Valve guide clearances and the valve job all good. I had the guides cut down to allow a decent street camshaft.​

 
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