Part Identification, Pretty Please - JeepForum.com
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post #1 of 12 Old 09-12-2021, 04:40 PM Thread Starter
cj5chic
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Part Identification, Pretty Please

What is this, what's it called and do I really need it?

Thanks for your help!

1980 CJ5
258
T176

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1980 CJ5, T176, Dana 30, Dana 300, mostly original
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post #2 of 12 Old 09-12-2021, 04:54 PM
OrangeCJ-5
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That door is vacuum operated so…that is a check valve?
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post #3 of 12 Old 09-12-2021, 05:14 PM
claudvandebek
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Quote:
Originally Posted by OrangeCJ-5 View Post
That door is vacuum operated so…that is a check valve?
I think thats what it is yeah
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post #4 of 12 Old 09-12-2021, 10:14 PM
JEEPFELLER
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I have 4 years of plumbing school in my resume (not bragging, just understanding stuff a bit better than your average bear)

If this were a check valve, it would "Check" after the air got sucked out, this would keep the apparatus/ fixture in that Open or Closed position---like forever! Unless the line could purge between the check and it's slave.

In other words---if it had been manufactured in "That Position" there would be no need for it to have another position for it to move into!

This is my theory on it-----that vacuum hose is not live full time, it's getting switched off and on from another location

The diagram I found if from my '77 factory service manual-----it's showing "304" diagrams on the right.

If this operates similar to the 304, that device might allow this system's vacuum air to escape once the line gets turned off (by maybe the thermal sensor?)--this would permit the door or whatever to relax back into it's "Default Position" until the vacuum signal is turned back on.

Maybe I'm wrong---but that's how I'm interpreting it.

-----JEEPFELLER
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post #5 of 12 Old 09-12-2021, 10:36 PM
BagusJeep
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It is a delay valve.

There are several in the vacuum systems and the color coding tells you which spec this one is. Should have been J323 7141, white yellow, but you have J323 7131 in there. Probably makes no difference, it just delays opening of the vacuum solenoid to give smoother operation. You need it for smoothness.

I worked on the ventilation system for a nuclear lab at one time, a vendor installed pneumatically operated dampers. Press the button and clang, clang, nearly sucked the lab walls over as it all switched around. By delaying the pressures the changeover was smooth, i just put some $5 restrictors on the outlets from the pneumatics.

There is a check valve under the air cleaner, and is a different circuit.
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1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
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post #6 of 12 Old 09-13-2021, 10:31 AM
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Bagus Jeep,

I've come across these in more modern vehicles (Fords)

https://www.amazon.com/Dorman-Help-4.../dp/B000CO7APW

They choke down the vacuum line to a smaller restricted size---I assume this works similar to the item the OP asks about?

You still get the FULL vacuum, its just delivered at a slower slower rate (if that's the way you refer to air backing out thru it)

Kinda like water barely trickling out of a faucet that is turned on wide open----The pipes are internally restricted with rust----the owner claims there is low water pressure----but the pressure is still at 100% using a gauge-----delivery has been choked down.

I've found the part in my link on the advance for the distributor, my guess has been to slow the actuator down so that it slowly changes the advance (up or down) Instead of an "instant" change.

Since I discovered them, I've wondered if using one on my distributor might benefit my 258 in any way? (economy is what I strive to better)

It's hard to find someone that "actually" might give an accurate answer, instead of a wild guess.

------JEEPFELLER
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post #7 of 12 Old 09-14-2021, 04:47 AM
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Yes, you would get a similar effect on the air cleaner trap door if you plumbed in one of those, the delay valve just slowly leaked air either way. Just need to slow it down.

However it is unclear how large the orifice is in the restrictor or delay valve so no way of guessing if it would move the actuator in the same time. As stock it took 100 seconds for the trap door to reverse once the TAC temperature sensor kicked in, so it must be quite a small orifice.

On your distributor?

Vac Advance can be hooked up to manifold or ported vacuum. Assume manifold. You take your foot off as going downhill, vacc increases, advance increases, no popping. Hit the bottom, foot down, vacc drops, advance decreases. Off you go.

I am not sure in any of that a delay to the operation of the advance would put you in a better position. AMC laden the engine bay with valves, restrictors and plumbing but the distributor ran on pure manifold vacuum.

One thing you can do is make sure you have a 13 or 18 head in the distributor (degrees of distributor, which as it moves at half speed is doubled up for the crankshaft) which with 10 degrees static advance will be good for up 36 to 46 degrees total advance. I was watching PowerNation on Youtube playing with the AMC I6 and I think they got max at 36 degrees total, but many swear by more.

Oh, and check your timing marks are accurate, the balancer / pulley can slip and you will swear you are correctly timed but have no power. And check the cam chain is taut, they get sloppy with age which plays around with the timing.

Then check your vacuum can does not leak and maxes out the arm movement at idle. There are more precise measurements possible.

BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #8 of 12 Old 09-14-2021, 01:07 PM
Matt1981CJ7
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There should actually be another delay valve on the other side of the air cleaner that controls the heat door. Both delay valves serve the same purpose of preventing the trap doors in the snorkel from slamming open and closed.

Perhaps a diagram will help.

Matt
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post #9 of 12 Old 09-16-2021, 04:56 PM
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This is a chart that I use to guestimate what delay valve to use. Most of the time this is to just delay the vacuum some. As stated above a smaller orifice will do the same by delaying the vacuum.
$0.02 worth
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post #10 of 12 Old 09-17-2021, 01:11 AM
BagusJeep
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UTN, excellent info.

So the one on there is delaying the door by too much.
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BagusJeep lives in Bali with far too many 4x4s:
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
1980 Land Rover Series III 109" troop carrier - ROVER
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post #11 of 12 Old 09-26-2021, 12:30 PM Thread Starter
cj5chic
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Quote:
Originally Posted by Matt1981CJ7 View Post
There should actually be another delay valve on the other side of the air cleaner that controls the heat door. Both delay valves serve the same purpose of preventing the trap doors in the snorkel from slamming open and closed.

Perhaps a diagram will help.


Matt
Matt,
I need one white/yellow and one grey/white check delay valve?
Where can I purchase these?
Thanks for the info!

1980 CJ5, T176, Dana 30, Dana 300, mostly original
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post #12 of 12 Old 09-26-2021, 12:41 PM Thread Starter
cj5chic
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Or maybe these are working just fine. How do I know for sure?

1980 CJ5, T176, Dana 30, Dana 300, mostly original
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