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390 4bbl
https://slantsix.org/forum/viewtopic.php?t=49850
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Author:  patrickhenryhague [ Thu Sep 20, 2012 3:59 am ]
Post subject:  390 4bbl

Anyone have experience with mounting Holleys sideways (floats sideways to the engine) I see this done on the Ford 300 but that is on a dual plane manifold and they keep the primarys close to the engine.

Author:  DusterIdiot [ Thu Sep 20, 2012 5:34 am ]
Post subject:  Yep...

I mount my carbs on my hyperpak intakes that way (in one case it's required as I split the manifold plenum). I did it on an Offy intake I have and didn't appreciably notice any difference in fuel dispersion (on the open plenum hpak it "evened out" the spark plug color).

-D.Idiot
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Author:  kesteb [ Thu Sep 20, 2012 9:36 pm ]
Post subject: 

On the other hand, GM mounted the carburetor with the secondaries toward the engine on the Pontiac Sprint OHC, so did Mercedes before they went FI.

Author:  wjajr [ Fri Sep 21, 2012 7:52 am ]
Post subject: 

I think mounting as PMD with primaries more distant from cylinders three and four helps to equal out runner length on a slant stock stile manifold. Having secondaries inboard is of less consequence where they are infrequently open for short durations during normal on road driving.

That said dividing manifold between front three and rear three cylinders in plenum below carburetor would perhaps improve vacuum signal it sees, and perhaps makes more low end torque… I don’t know for sure, others here can pontificate at a higher level on this subject than I, and I welcome their impute on the subject.

I looked into performing this modification to a Clifford intake to accommodate a Holley 390, but with Chrysler adapter attached to throttle shaft I would have to increase the spacer below carburetor to allow its full rotation to where the screw attaching air cleaner would perhaps contact hood. At the time I was in a pucker to get the car running, along with too much hood insulation, and no real dummy spacer to make positive measurements, or a test fit, I temporarily passed on the project.

Author:  cum*do_ge [ Fri Sep 21, 2012 6:28 pm ]
Post subject: 

I added a plenum divider into an Offenhauser, creating a dual-plane intake. I think it's the way to go on a street engine. It made carb tuning simpler, to not worry about rich/lean cylinders.
This carb is a 1958 Ford F4, the old 'Crackerbox'. It was manufactured by Holley for Ford, and uses Holley jets (up to about '65 or so) It's a smaller cfm'ed carb, with annular-discharge boosters.
Image

Author:  Rug_Trucker [ Fri Sep 21, 2012 6:38 pm ]
Post subject: 

I have an Offy Dual Port on my 360. It is still a 360* single plane. Not a 180* Secondaries have a seperate route.

I doubt the 300 was a dual plane. Just a divided single plane.

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