Vacuum Functions 327/Holley 2 Barrel

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Vacuum Functions 327/Holley 2 Barrel

Post by Harry Dawg »

Merry Christmas and Happy Holidays everyone!
Finally got some time off and have been working on the J3000.
Hoping for some input on Vacuum line function on the factory 2 barrel.
There is a plate below the carb that has 3 vacuum lines run off it.
Can someone identify what they are and if possible the function of each? I have labeled them for easy reference.
There is also a lone tube that goes from the side of the carb back into the intake. Is this some sort of early fuel return system?
PXL_20211224_195321067~2.jpg
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Last edited by Harry Dawg on Thu Dec 30, 2021 4:35 pm, edited 1 time in total.
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

This is the lone tube in question
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Update for anyone out there that might benefit from this info.
I posted this on an FSJ Facebook group and was told that A would be for a power break booster, B is the PCV valve and C would be accessories.
At least I got a starting point!
Here is the link to the Facebook page for anyone interested. https://www.facebook.com/groups/44932762557
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Re: Vacuum Functions 327/Holley 2300

Post by will e »

The long tube is used for the choke. It heats the choke so that it slowly opens after the engine has been running for a bit.
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Re: Vacuum Functions 327/Holley 2300

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Thanks for the info.
That's pretty interesting. I an wanting to put a different carb on there which I believe will be a manual choke. Should I just plug that hole with a bolt?
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Re: Vacuum Functions 327/Holley 2300

Post by tgreese »

To the OP, a FSM reprint is available for your truck. https://www.bjsoffroad.com/1965-1971-Je ... _1055.html

May be available on CD-ROM for less on RockAuto. Good to have even at full price in paper. BJ's will give you a modest discount as a member of this forum.
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Re: Vacuum Functions 327/Holley 2300

Post by will e »

Harry Dawg wrote: Sat Dec 25, 2021 10:34 am Thanks for the info.
That's pretty interesting. I an wanting to put a different carb on there which I believe will be a manual choke. Should I just plug that hole with a bolt?
I don't know. First, confirm it is connected to the choke.
The one on my 73 Mustang was a closed circuit, it didn't pass any exhaust. So, disconnect it and see if there is any pressure while the engine is running.
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Thanks @tgreese.
I found ordered one on eBay that was a little less expensive.
Not knocking BJ's though! I just purchased the Dana 44 closed knuckle rebuild kit, emission line delete bolts, oil pan, valve cover and intake manifold gaskets from them. Should be here on Thursday.
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Update for anyone interested.
This is not necessarily related to Vacuum functions, but does involve this specific carburetor setup.

After removing the carburetor I think I have a bit of an oddity on my hands.
The base plate on the 2300 has a unique bolt pattern that I believe may be specific to this intake manifold. (Correct me if I am wrong)
5-1/8" X 3 1/2" IIRC.

I have not been able to find a bolt on replacement aside from a new Holley 2300 for $600.
If that is my only option, I believe I will fork over the extra $400 and get the 2300 EFI kit from Holley.
Ideally, I can figure out somewhere to source a custom carb adapter so that I can use the Motocraft 2100.

The base plate contains the vacuum ports, so in theory I should be able to leave it and bolt a carb/adapter on top.
Thoughts?
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Re: Vacuum Functions 327/Holley 2300

Post by tgreese »

The 2V Holley pattern is an industry standard, widely available, and well supported. The Motorcraft 2100 and 2150 2V carbs used by AMC (and Ford!) are the same pattern. Look here -
https://www.rockauto.com/en/catalog/ame ... sket,10024
This is a Holley 2V pattern.

JMO - unless I really wanted a performance boost, I would send my OEM carb to a professional shop for refurbishment. NB the Holley carbs are simple and a rebuild by an amateur is easy and inexpensive.

I would also point out that the Holley 2300 sold aftermarket is a performance carburetor, and will need to be tuned to your application. You will need to buy and try speed shop tuning parts, and be able to assess when you've arrived at the proper tune. Plus the performance Holleys are terrible off-road carburetors without a bunch of mods.

If you want to spend the money, EFI is an excellent upgrade, especially for a Jeep.

Note that any plate between the carb and manifold that is not connected to the carb is nominally an "insulator." Some aluminum insulators have coolant piped through them to warm the carburetor, some are made of plastic to keep the carb cool. Some Holleys and Motorcrafts use an insulator with a vacuum port that connects to the PCV valve.

The smaller ports on a carb can be ported vacuum, or simply manifold vacuum. These ports receive the same vacuum signal as the manifold, but ported vacuum is blocked by the throttle plate at idle, thus goes to zero at idle. Test the port with a vacuum gauge or with the tip of your finger - you can tell the difference as the throttle plates close.

The tube you show in post 12 does look like a filtered air intake for the choke stove. Above the venturi is close to open air, not vacuum.
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Thanks for your input Tgreese.

The carb shop near me wanted $900 for a rebuild, which sounded outrageous so I didn't pursue this route any further.
I did see where a rebuild kit was available, but after reading some folks input on that carburetor, I was under the impression that these aren't that desirable. I am not familiar with the hot air choke, and I just have my doubts about this carburetor and it's ability to preform. It most definitely had some bad gas ran through it (rancid rusty gas that got sucked all the way into the fuel filter....pic attatched) so I am wondering if it is compromised.

The performance 2300 doesn't sound like what I need/want. Mainly just threw that one in there because I thought it was the only option for a direct bolt on. As for the Sniper EFI, that isn't exactly what I am wanting just yet, but again, it looked like a direct and easy bolt up.
Basically just thinking that if I can't figure out carb tuning then I can throw that one on there and go.

What I really like the idea of is the Motocraft 2100. It is an affordable option for me at this time, and I have heard it has decent offroad performance.
I also like that it can be converted to a manual choke (The more simple the better for me.)

*Important* - I am under the impression that I can run a return line with this carburetor, which mine does not have.
I am assuming the mechanical fuel pump is FUBAR'd from sucking in rust, as it is plumbed before the fuel filter for some reason (see below fuel filter in photo)
I am planning to run new fuel lines and am thinking I will run an inline electric fuel pump. 4-6 PSI is what I was shooting for, is that a fair flow for a 500 CFM carb?

Pics attached for reference.
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Intake
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Re: Vacuum Functions 327/Holley 2300

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Intake
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Fuel Filter
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Re: Vacuum Functions 327/Holley 2300

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Harry Dawg wrote: Wed Dec 29, 2021 5:47 pm Thanks for your input Tgreese.
NP.
The carb shop near me wanted $900 for a rebuild, which sounded outrageous so I didn't pursue this route any further.
I did see where a rebuild kit was available, but after reading some folks input on that carburetor, I was under the impression that these aren't that desirable. I am not familiar with the hot air choke, and I just have my doubts about this carburetor and it's ability to preform. It most definitely had some bad gas ran through it (rancid rusty gas that got sucked all the way into the fuel filter....pic attatched) so I am wondering if it is compromised.
Yeah, that seems like a lot. Quite likely they don't want your business. There is more than one carb shop. Certainly that $900 puts you well in the range of Sniper EFI. I would go that route, if I had no other reason to stay with a carburetor. Plenty of discussion of this - pro and con - in other threads. There are other sellers that modify Rochester TBI, which makes your system all-GM except for the chip in the ECU.
The performance 2300 doesn't sound like what I need/want. Mainly just threw that one in there because I thought it was the only option for a direct bolt on. As for the Sniper EFI, that isn't exactly what I am wanting just yet, but again, it looked like a direct and easy bolt up.
Basically just thinking that if I can't figure out carb tuning then I can throw that one on there and go.
Yes, that will bolt on. It's another 2300, basically the same as what you have. There is also a 350CFM version which would be more appropriate to this engine IMO. Carburetors use vacuum as both a signal and as a power source to move and meter the fuel. A too-big carburetor cannot control the fuel accurately at low speed, and as a result must be set-up excessively rich to be drivable.
What I really like the idea of is the Motocraft 2100. It is an affordable option for me at this time, and I have heard it has decent offroad performance.
The 2100 is an excellent carburetor, and works well on the trail. However, I would expect any factory carburetor from Jeep to be set up for off-road usage. I have no personal experience with the 2300 on the 327, but I would guess it's fine in that department. The performance 2300 is meant for flat track racing, and does not work well over broken terrain (bounce) or off-angle (side hill).

The 2300 can be modified to work better on the trail. This requires some minor fab and some Holley service parts. Should be something online about this if you search. These mods would apply to your Jeep 2300 too, if something equivalent was not already done by Jeep.

One issue withe the 2100 - it is not as configurable as the Holley. It only has a few settings that are accessible externally. The jets are its own. Supposedly the Quick-Fuel power valves work, but Motorcraft valves are different from the Holley valves. Holley provides many usefule tuning parts and accessories, unlike Motorcrfat which is exclusively OEM. A new Motorcraft will be a repop from overseas.
I also like that it can be converted to a manual choke (The more simple the better for me.)
The 2300 is easier in this department. This should bolt on to your existing 2300 - https://www.amazon.com/Holley-45-225-Ma ... 5435&psc=1 - indeed I have mixed and matched choke parts between the (Ford) Motorcraft and Holley carbs, and I suspect this kit would work on a Motorcraft too.

Most would use the Dorman kit for a 2100 https://www.amazon.com/Dorman-HELP-5510 ... B000CO7CK0 - It's not ideal. The cable bracket is really flimsy, and it keeps the stepped fast idle cam of the automatic choke. Thus you need to manipulate throttle while you pull the cable, to make it idle up or down. Not as good as a genuine manual choke.
*Important* - I am under the impression that I can run a return line with this carburetor, which mine does not have.
I am assuming the mechanical fuel pump is FUBAR'd from sucking in rust, as it is plumbed before the fuel filter for some reason (see below fuel filter in photo)
I am planning to run new fuel lines and am thinking I will run an inline electric fuel pump. 4-6 PSI is what I was shooting for, is that a fair flow for a 500 CFM carb?
Mechanical fuel pumps are quite reliable when not plugged with rust. If you think you have rust in the tank, the right solution is to drop it and clean it out, possibly coating it at that time.

A filter before the fuel pump is not usual. Normal location is on top of the engine. There should be a screen (filter sock) on the end of the fuel pickup in the fuel tank that filters out any large particles. Possible that's missing. See JPSU-1 and JPFF-1 here http://www.mtscompany.com/J-truck.htm

If you want to run a return line, I'd suggest the 3-nipple fuel filter that Jeep uses with the AMC V8s. That goes up by the carburetor, and does not depend on the carburetor type.

The later TSMs have a fuel pressure spec for their carburetors. Look in your TSM. With a carburetor you don't need much pressure - it will run from a can on the cowl, fed by gravity. BTDT.
Tim Reese
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Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
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Re: Vacuum Functions 327/Holley 2300

Post by tgreese »

Looking at your pictures above, and the parts book, your original carburetor is not a Holley 2300. Some 327s came with a 2300, but Jeep also supplied what appears to be a Holley 2209. Should be a R-3234-1 or a R-3262-1.

I'd guess this is your rebuild kit: https://www.rockauto.com/en/catalog/ame ... r+kit,5964 ... the Hygrade 362B.

You can find lots of pictures of this carburetor online if you search.

Suggestion - become a member here https://theamcforum.com/forum/forums.html and ask for a recommendation for where to send your carburetor. The AMC car guys should have more experience repairing these engines. This guy was recommended on another site http://oldcarbdoctor.com/index.html Tell them you have a 2209.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
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Re: Vacuum Functions 327/Holley 2300

Post by Harry Dawg »

Sorry for leading you on a wild goose chase Tgreese!
The serial number is actually R-3601-A. I should have started with this.
I have found limited information on this serial number on the web aside from this blown up diagram.
https://www.carburetion.com/CarbNumber.asp?Number=R3601
The TSM is in the mail, so this will hopefully clear things up a bit.
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Re: Vacuum Functions 327/Holley 2 Barrel

Post by tgreese »

There is a parts book here https://oljeep.com/edge_parts_man.html that shows your carburetor and application. The R-3601-A was used on the 327 with an exhaust emission pump (air injection, smog pump).

I assumed the 2300 pictured in that book was for the 327 and am mistaken - according to the parts book, only the 2209 was used with the 327. The 230 inline 6 got the Holley 2300 for some applications, but not the 327. Kaiser bought these engines as a commodity from AMC, so they likely accepted whatever carburetion that AMC had chosen. Possible the carburetors for Jeep have internal mods that make them better for this application, ie trail use.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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