Re: 426 Hemi factory 6 pack intake?
[Re: Lee446]
#299849
04/26/09 11:20 AM
04/26/09 11:20 AM
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Joined: Dec 2007
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I just got Larry Shepards book on Hemi's. According to him, Mopar Performance is marketing a 6 pack intake for the Hemi. Anyone seen or heard of it?
MP was going to release one, never going to happen , not now, with Chrysler wasteing by the roadside like it is,.....MP released their one and only plastic prototype several years ago, if it didn't happen then, it ain't going to happen now .....the manifold that I offer is a conversion of a factory dualquad converted topside and internaly into a true dualplane sixpack Hemi manifold, allowing full use of factory and repro carbs and air cleaner systems, I've had several in street use for about 8 yrs now, no issuses, very steetable, more so than the quads, very tunable, and gas mileage is very respectable, and performance IMHO is awesome!
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Re: 426 Hemi factory 6 pack intake?
[Re: Lee446]
#299852
04/26/09 04:32 PM
04/26/09 04:32 PM
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Joined: Dec 2007
Posts: 18,167 Mass
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So, How much does it run to have the manifold modded into a sixpack? I assume you use the AFB style manifold and not the Marine version? I like the idea of the sixpack, been running them on my wedges for years! Lee.
Lee,.....correct regarding the AFB manifold, the marine manifold dose not lend itself to the conversion because the plenum area between the carbs is stepped down, when I convert the AFB manifold, I need to machine ports and runners into that area to "support" the function of the center carb,.....there's no welding in my conversions, just a lot of machining, hand porting, and 2 stepped/knurled carb port plugs inserted into the primary bores of the rear quad carb bores, and 2 stepped/knurled plugs in the secondary bores of the front quad carb bores, the end result is a true six barrel manifold of dualplane design, .300 is then machined off the top of the manifold after its converted, and a 1 piece boss top plate is bolted to the top to recieve the sixpac carbs, with the boss plate bores, lining up with the "new" sixbarrel bores in the manifold, then all the runners/bores are ported for flow,......price $1200+stock manifold
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Re: 426 Hemi factory 6 pack intake?
[Re: LimeliteAero]
#299855
04/26/09 07:22 PM
04/26/09 07:22 PM
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Joined: Dec 2007
Posts: 18,167 Mass
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I have no knowledge of hemi engines but I fail to see an advantage of the six pac intake over the dual quad. can someone explain what Im missing?
Dave,.....As far as the quads, you can't touch them at top end, as far as induction systems go......the sixpack, (1) offers you something that's a little more responsive in the low-mid range RPM, a few elephants have fallen on their faces in the streetlight races because of the delay in swallowing all that air from the quads when it being stomped on,.....(2) when you study the quad idle circit, port flow/reversion, deposits/wash and sparkplug evaluation, you see that the Hemi suffers from cylinders leaning in 5,7,and 8,.....with the idle cicuit of the sixpack, you have 3 carbs, evenly distributed along the manifold, doing a rather nice job of feeding the cylinders, from what I've seen on several Hemi motors that I've prepared over the years, the only cylinder that I've noticed running lean with the Hemi Sixpack is number 7, reason being is the lower runner in the dualplane, their not much porting that I can do without breaking into the lower runner for cylinder 7, as #7 is feed from the passenger side of the manifold, the rear carb throttle bore for cylinder 8 is directly above the #7 runner.....but simple jetting on that side of the rear carb, retifies the situation, (3) fuel economy can be greatly improved over the quad set-up, on Keisler equipped (5spd .64 OD) Hemis.....had one car with 4;10's getting 16-18MPG on the highway at 75-90 MPH cursing speeds.....and another with 3:54's getting almost 20 MPG cruising in the 90 MPH range,.....both cars having 600HP+ engines,......(4) just looks pretty DAM COOL!
Tom Hoover, created the sixpak manifold around late 69,.....tested it in his personal 66 Hemi Coronet,....as plans called for it's introduction in the 71 model year,....but by May of 1970, Chrysler issued a "death call" for the hemi in production to shortly end with 71 production year, ....so the sixpack Hemi manifold, of which only 3 were made was canceled, along with other Hemi programs slated for 70/71
I released my first manifold in 2002 on a 1971 customer's car, working from pictures I had of Hoover's manifolds
They are extremely streetable, very responsive, and easly tuned......it's to bad Chrysler didn't release these for production in 1971 as planned, I think it would have made for some interesting cars?
Mike
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