Dual 4 bolt (4 screw) 46mm SU intake manifold

Engine, Transmission and related drivetrain.
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Beev
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Joined: 11 Apr 2018 13:49

Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Beev » 21 Jun 2019 14:02

Hello Again,

I have already asked one reliable resource about this but in the hopes that something exists I though I would throw this question out there. Does anyone know of a Dual 4 bolt (4 screw) 46mm SU intake manifold for a U67 head that has a vacuum pickup off runners 1/2, 3/4, and at least one off the ballancing tube? I currently have one that only has it off the ballancing tube and 3/4 runner. I have attached a picture of my current setup. Note if the answer turns out to be yes I would likely move this to the classifieds for WTB.

Thanks!

https://photos.app.goo.gl/xiUQkUs2TDxr1pCW6
https://photos.app.goo.gl/uzdpg8wbpu6wFNeb9

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Byron510
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Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Byron510 » 26 Jun 2019 06:09

I am pretty sure the 4 bolt SU manifold is a custom piece. The factory Nissan SU manifold for the L series (SSS) was a 2 Bolt flange for the 2 Bolt SU’s.
The 4 bolt SU’s were used in the 6 cylinder applications, but never on the 4’s as far as I know.
Mike Yarn had a local foundry cast a 4 Bolt SU manifold about 20 years ago. I’m unsure is others have also cast a similar animal.

I’ll assume you are trying to solve your pulsating signal to your MAP sensor with this question? Based on your photos, I would think that the 4 bolt flange itself has enough meat on it to drill and tap a port into it for your vacuum signal on both runners.

Byron
Love people and use things,
because the opposite never works.

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Chadsinto510s
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Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Chadsinto510s » 26 Jun 2019 09:49

I don't have pics right now but, I cut the mounting blocks off of a z-car manifold and had them welded to a 2 bolt manifold so I could use z-car su's. Works GREAT.

Beev
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Joined: 11 Apr 2018 13:49

Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Beev » 27 Jun 2019 14:31

Ha yup the pursuit of flutter and getting a ballanced signal for the map. I have been able to remove the flutter with use of a reservoir but only off runners 3/4. It works and I am hesitant to put extra holes in the manifold but perhaps we can chat next time I see you.

Yeah I have talked extensively with Mike and Pam from ZTherapy.

Chad thanks for the idea. If I decide I need this i will keep that route in mind.

For now it seems nothing exists as is.

datzenmike
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Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by datzenmike » 27 Jun 2019 18:33

Image

I agree with Byron all L4 were 2 bolt but a 4 bolt carb will mount to a two bolt manifold. The 1.6 liter Roadster used a 4 bolt SU carb. There would be no need to draw from each runner when there is the 'balance tube' to collect for the brake booster and PCV valve already in place. What's wrong with the balance tube it collects from all four runners?
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

Beev
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Joined: 11 Apr 2018 13:49

Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Beev » 28 Jun 2019 14:28

The issue is getting a clean signal and having an IAC valve. They need to be separate and the IAC for sure needs to feed all cylinders equally. This could potentially be done with a large enough reservoir on the ballancer but runs the risk of the computer fighting the signal of loss of vacuum and opening the IAC.

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Tedman
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Re: Dual 4 bolt (4 screw) 46mm SU intake manifold

Post by Tedman » 28 Jun 2019 21:03

OP is in uncharted territory. Vaya con Dios!

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