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> Decel Valve Hose Connection Check, Which is correct?
FlacaProductions
post Oct 12 2024, 07:44 PM
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I've done a lot of reading on this - prepping to re-install the decal valve. I have a good valve and new hoses.

Does this picture show correct routing?

ie: "side" port going to the top/side of the airbox.
(pic originally from @TJB/914)

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JeffBowlsby
post Oct 12 2024, 07:57 PM
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The early 74s 2.0 are like the 73s with the charcoal filter on the fuel tank. Late 74s are like this:

https://bowlsby.net/914/Classic/zTN_FI_Hose..._Late1974_A.jpg

PS I just checked the decel valve hose routing on both the 73 and 74 2.0s. Same-same.
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FlacaProductions
post Oct 12 2024, 09:31 PM
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Understood. Thank you, Jeff!
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FlacaProductions
post Oct 13 2024, 06:08 PM
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I'm confused @JeffBowlsby
Went out to do the decel valve install and found the hose sizes to be different from what's listed on your guide.

Capped connection on the left (which should be for hoses #15 and #9 via a branched adapter) is smaller than the one on the right. The short leg on the right (which should be for hose #13) currently connects to a "step-up" adapter that then goes direct to the PCV valve and fits correctly just like hose #9 should be.

Branched elbow is too big for either one of these nipples.

Connection on upper, passenger side of the airbox (hose #14) is correct for the direct line to the decel valve.

This is a "late 74" 2.0 setup with the canister on the rear wall of the engine compartment.

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JeffBowlsby
post Oct 13 2024, 06:53 PM
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The 75-76 air plenums have different port sizes as I recall. Youwill need the correct 73-74 air plenum.

See if you can find an image of the 75-76 plenum to confirm that’s what you have.
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JeffBowlsby
post Oct 13 2024, 07:54 PM
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73-74 Note the two side port relative sizes.



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JeffBowlsby
post Oct 13 2024, 07:56 PM
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75-76 - Smaller side port (it appears to have a cap on it). Is this like yours? If so it’s been changed from the original 74 style at some point. All 2.0s are not the same in every way, there are several differences between the 2.0s in 73, 74, 75, 76 model years and this side port on the air plenum is one of them.


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FlacaProductions
post Oct 14 2024, 06:36 AM
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Yup - appears i have a later plenum.
Interesting.
I guess if i want to add the decel valve back in, I'll need to do some hose adapting...thank you!
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JeffBowlsby
post Oct 14 2024, 08:07 AM
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Or find the correct 73-74 plenum.

Or maybe there is another easier way...The 75-76 cars also had the decel valve so plumb it like those cars. Maybe its as simple as connecting the hoses up to the plenum differently. 73-74 plenum diagram below for reference.

Can you tell me what the port ODs are for the two ports on the side and the vertical one on the top? The 73-74 plenum has 10mm, 13mm and the top is 8mm.



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emerygt350
post Oct 14 2024, 03:39 PM
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Yeah. As long as you have manifold at the top, fresh at the side, and manifold at the bottom, you should be able to make it work.

Yet another reason to have a vacuum gauge on the dash. When I had mine hooked up incorrectly it was really easy to see....
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dr914@autoatlanta.com
post Oct 14 2024, 03:46 PM
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front and rear ports to vacuum side port to air cleaner, small fitting facing forward, device stacked on top of the pressure sensor

QUOTE(FlacaProductions @ Oct 12 2024, 06:44 PM) *

I've done a lot of reading on this - prepping to re-install the decal valve. I have a good valve and new hoses.

Does this picture show correct routing?

ie: "side" port going to the top/side of the airbox.
(pic originally from @TJB/914)

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dr914@autoatlanta.com
post Oct 14 2024, 03:47 PM
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also the air cleaner and sheet metal should be semi gloss and the boot is missing on the end of the engine release cable

QUOTE(dr914@autoatlanta.com @ Oct 14 2024, 02:46 PM) *

front and rear ports to vacuum side port to air cleaner, small fitting facing forward, device stacked on top of the pressure sensor

QUOTE(FlacaProductions @ Oct 12 2024, 06:44 PM) *

I've done a lot of reading on this - prepping to re-install the decal valve. I have a good valve and new hoses.

Does this picture show correct routing?

ie: "side" port going to the top/side of the airbox.
(pic originally from @TJB/914)

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emerygt350
post Oct 14 2024, 04:30 PM
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Engine release cable? That sounds dangerous!
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FlacaProductions
post Oct 14 2024, 07:18 PM
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Thanks for all of this input.
My time in Indiana monkeying around with the 914 has come to a close so my flurry of posts will taper off as well. Until I get home and do a little more research and concoct a plan.

@JeffBowlsby - I did not bring my calipers on this trip (it stinks having cars and parts and tools scattered between two states) so I can't give you measurements on the ports - but will do so upon return. Thanks again.
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