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426 Street Hemi intake manifold question ?
#3158044
07/08/23 02:57 PM
07/08/23 02:57 PM
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Joined: Feb 2009
Posts: 19
USA
DARTGTS340
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Anyone know the reason for the plenum notch under the primary bores of the rear (primary) carb?
Last edited by DARTGTS340; 07/08/23 03:03 PM.
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Re: 426 Street Hemi intake manifold question ?
[Re: DARTGTS340]
#3158047
07/08/23 03:02 PM
07/08/23 03:02 PM
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Joined: Aug 2003
Posts: 43,195
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
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Bend,OR USA
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Anyone know the reason for the plenum notch under the primary bores of the rear (primary) carb? For drag racing 4 speed cars  If your driving it on the street mainly don't do that 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 426 Street Hemi intake manifold question ?
[Re: Cab_Burge]
#3158050
07/08/23 03:07 PM
07/08/23 03:07 PM
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Joined: Feb 2009
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USA
DARTGTS340
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No this notch or cutout is about 1/2 inch deep connection of the rear carb only primary bores and is on all stock factory street Hemi intakes. I tried to post up a picture but had an issue.
Last edited by DARTGTS340; 07/08/23 03:12 PM.
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Re: 426 Street Hemi intake manifold question ?
[Re: DARTGTS340]
#3158057
07/08/23 03:24 PM
07/08/23 03:24 PM
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Joined: Aug 2003
Posts: 43,195
Bend,OR USA
Cab_Burge
I Win
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I Win
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Bend,OR USA
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That is used to have the same amount of vacuum to both idle circuits on the rear, primary, carb.. I thought you were referring to removing that divider all the way to the plenum floor like Mopar use to recommend for 4 speed drag cars, sorry 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 426 Street Hemi intake manifold question ?
[Re: Cab_Burge]
#3158063
07/08/23 03:35 PM
07/08/23 03:35 PM
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Joined: Feb 2009
Posts: 19
USA
DARTGTS340
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Re: 426 Street Hemi intake manifold question ?
[Re: DARTGTS340]
#3158074
07/08/23 04:59 PM
07/08/23 04:59 PM
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Joined: Mar 2011
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Michigan
A727Tflite
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Nothing to do with vacuum. EDIT. little to do with vacuum.
It was done to correct fuel distribution problems on cylinders 5 & 6.
Last edited by Transman; 07/08/23 05:03 PM.
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Re: 426 Street Hemi intake manifold question ?
[Re: A727Tflite]
#3158077
07/08/23 05:17 PM
07/08/23 05:17 PM
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Joined: Jan 2004
Posts: 8,273
fredericksburg,va
cudaman1969
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fredericksburg,va
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Nothing to do with vacuum. EDIT. little to do with vacuum.
It was done to correct fuel distribution problems on cylinders 5 & 6. Winner Winner, and from what I read Chrysler never got it right
Last edited by cudaman1969; 07/08/23 05:18 PM.
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Re: 426 Street Hemi intake manifold question ?
[Re: topside]
#3158131
07/08/23 09:20 PM
07/08/23 09:20 PM
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Michigan
A727Tflite
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Distribution seemed to be all over the place on mine, but likely aggravated by a pretty big cam profile.
We ended up with pretty much every corner being different, but after that it ran clean & mean.
Could arguably have been better with a single big carb, but I wanted a stockish look. There was three distinct “curves” for distribution depending on engine speed using the stock manifold. Chrysler was locked in on the manifold design for 1966 due to planned launch dates. I was always surprised they never did anything to further improve on that manifold design for the street. Maybe subtle carb changes gave them what they needed.
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Re: 426 Street Hemi intake manifold question ?
[Re: A727Tflite]
#3158137
07/08/23 09:52 PM
07/08/23 09:52 PM
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Joined: Jan 2004
Posts: 8,273
fredericksburg,va
cudaman1969
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Distribution seemed to be all over the place on mine, but likely aggravated by a pretty big cam profile.
We ended up with pretty much every corner being different, but after that it ran clean & mean.
Could arguably have been better with a single big carb, but I wanted a stockish look. There was three distinct “curves” for distribution depending on engine speed using the stock manifold. Chrysler was locked in on the manifold design for 1966 due to planned launch dates. I was always surprised they never did anything to further improve on that manifold design for the street. Maybe subtle carb changes gave them what they needed. The people who bought the Hemi didn’t care too much about running perfect as long as it did well with foot to the floor imo.
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Re: 426 Street Hemi intake manifold question ?
[Re: A727Tflite]
#3158156
07/08/23 11:39 PM
07/08/23 11:39 PM
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Joined: Jun 2014
Posts: 1,326
VA
dragon slayer
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pro stock
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VA
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Distribution seemed to be all over the place on mine, but likely aggravated by a pretty big cam profile.
We ended up with pretty much every corner being different, but after that it ran clean & mean.
Could arguably have been better with a single big carb, but I wanted a stockish look. There was three distinct “curves” for distribution depending on engine speed using the stock manifold. Chrysler was locked in on the manifold design for 1966 due to planned launch dates. I was always surprised they never did anything to further improve on that manifold design for the street. Maybe subtle carb changes gave them what they needed. Do you have any technical notes on what the engineers were doing? I have wondered about the evolution of the carb jetting over the years. I get non emission/emission carbs, but Air bypass until 68, then some jet changes even on the 70 carbs.
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Re: 426 Street Hemi intake manifold question ?
[Re: dragon slayer]
#3158158
07/08/23 11:58 PM
07/08/23 11:58 PM
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Joined: Mar 2011
Posts: 3,077
Michigan
A727Tflite
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Distribution seemed to be all over the place on mine, but likely aggravated by a pretty big cam profile.
We ended up with pretty much every corner being different, but after that it ran clean & mean.
Could arguably have been better with a single big carb, but I wanted a stockish look. There was three distinct “curves” for distribution depending on engine speed using the stock manifold. Chrysler was locked in on the manifold design for 1966 due to planned launch dates. I was always surprised they never did anything to further improve on that manifold design for the street. Maybe subtle carb changes gave them what they needed. Do you have any technical notes on what the engineers were doing? I have wondered about the evolution of the carb jetting over the years. I get non emission/emission carbs, but Air bypass until 68, then some jet changes even on the 70 carbs. All I have access to is the 1966 Hemi Engine Development report/book. And bits and pieces from discussions with some of the Chrysler engine guys back In the 60’s and 70’s. 
Last edited by Transman; 07/10/23 09:18 AM.
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Re: 426 Street Hemi intake manifold question ?
[Re: A727Tflite]
#3158444
07/10/23 08:56 AM
07/10/23 08:56 AM
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Joined: Jan 2012
Posts: 2,651
Stuttgart, Arkansas
rickseeman
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I once saw what I assume was the first street hemi intake manifold. It was a work of art. It looked like a regular street hemi intake but was made out of steel tubing. Man those guys had fabrication skills. I guess this was used to test the idea on the dyno.
2011 Drag Pak Challenger
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Re: 426 Street Hemi intake manifold question ?
[Re: rickseeman]
#3158447
07/10/23 09:16 AM
07/10/23 09:16 AM
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Joined: Mar 2011
Posts: 3,077
Michigan
A727Tflite
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This one?
Last edited by Transman; 07/10/23 09:17 AM.
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Re: 426 Street Hemi intake manifold question ?
[Re: rickseeman]
#3158491
07/10/23 11:41 AM
07/10/23 11:41 AM
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Joined: Feb 2014
Posts: 1,708
central il.
second 70
top fuel
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top fuel
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central il.
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The marine manifold has that on each carb?
Last edited by second 70; 07/10/23 11:42 AM.
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Re: 426 Street Hemi intake manifold question ?
[Re: second 70]
#3158498
07/10/23 12:01 PM
07/10/23 12:01 PM
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Joined: Jan 2012
Posts: 2,651
Stuttgart, Arkansas
rickseeman
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Yes, if I remember correctly the "marine" intake is similar to the 67 RO/WO and Vanke intake.
2011 Drag Pak Challenger
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Re: 426 Street Hemi intake manifold question ?
[Re: rickseeman]
#3158521
07/10/23 01:22 PM
07/10/23 01:22 PM
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Joined: Mar 2011
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Michigan
A727Tflite
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No, this one was made out of steel tubing and of course covered in light surface rust. That is steel. Just painted. So you mean steel tubing, not steel sheet.
Last edited by Transman; 07/10/23 01:23 PM.
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Re: 426 Street Hemi intake manifold question ?
[Re: A727Tflite]
#3158522
07/10/23 01:24 PM
07/10/23 01:24 PM
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Joined: Jan 2012
Posts: 2,651
Stuttgart, Arkansas
rickseeman
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Yes, it was steel tubing, not fabricated. I was wondering how they got that tubing to bend so tight.
2011 Drag Pak Challenger
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