4 bbl carb on wrong? - Page 5 - JeepForum.com
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post #61 of 71 Old 07-03-2021, 09:10 AM
gutthans
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Quote:
Originally Posted by Shawn Watson View Post
I'm wondering if a Holly-style carb that uses a vacuum pod for secondary activation rather than a counter-weighted air flap would have worked well mounted forwards. Not that it matters here; just wondering.


Shawn
Don't think so on the Holley. You'd have one primary and one secondary barrel over each plane. That would mean the primary runner would have one barrel until the secondary side opened. And even with the second primary barrel working on the second plane, the velocity is slower (due to runner size) and it's farther away than the first barrel and every cylinder. It would definitely complicate mixtures getting to #'s 1 & 6 which are already a design issue with correct mounting. No way you'd ever get #6 to run well without over-enriching #1.


Last edited by gutthans; 07-03-2021 at 09:47 AM.
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post #62 of 71 Old 07-03-2021, 09:22 AM
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Hmmm, I see your point. Have I ever mentioned that I really don't like this intake design, lol.

Either way, I'm glad the OP got the carb situation straightened out.


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post #63 of 71 Old 07-04-2021, 11:15 AM
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Quote:
Originally Posted by Shawn Watson View Post
The port on the front side of the carb is the way to go. It's easy to want to plumb the rear of the carb for PCV where it's away from header heat and easy to access but now you're in trouble.

I wouldn't use the port in the intake for PCV. I'm sure it's fine with its non-directional suck for the brakes. Funky intake design, for sure. I'm wondering if a Holly-style carb that uses a vacuum pod for secondary activation rather than a counter-weighted air flap would have worked well mounted forwards. Not that it matters here; just wondering.


Shawn
Didn't think of that issue. explains a lot. And you're right I was only off by 90 degrees, I really meant 180. Silly me. I guess he has to drill and tap a port somewhere on top.
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post #64 of 71 Old 07-06-2021, 12:38 PM Thread Starter
85Tuxedocj7
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Originally Posted by gutthans View Post
I note in the first few pictures that there is a closed port on the secondary side. A second picture of the carb shows a nipple also on the primary side of the carb. Since the manifold itself has a port for the vacuum brake take-off, below the carb pad, it seems like that nipple can be plumbed for the PVC on the primary side. Yes???
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post #65 of 71 Old 07-07-2021, 08:44 AM
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Maybe I just didn't read enough or something????

There's a missing gasket on the right side of the pic above the butterfly

Is it missing? Did it get sucked in and now obstructing the carb flow?

Like I said, I'm probably at the wrong event here and stirring up things already covered.

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post #66 of 71 Old 07-07-2021, 09:04 AM Thread Starter
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Originally Posted by JEEPFELLER View Post
Maybe I just didn't read enough or something????

There's a missing gasket on the right side of the pic above the butterfly

Is it missing? Did it get sucked in and now obstructing the carb flow?

Like I said, I'm probably at the wrong event here and stirring up things already covered.

----JEEPFELLER
No, the gasket tore when I removed the carb, the dark colored butterflys are sooted up.
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post #67 of 71 Old 07-07-2021, 09:30 AM Thread Starter
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Originally Posted by Fourtrail View Post
Wherein lies part of the issue, the Edelbrock carb does have mechanical opening secondaries, but there is a weighted air valve between the venturi and the butterflies in the base plate. If you are not creating enough vacuum on the secondary side of the intake, the air valve will not open and no fuel will flow through. With the larger runners on the secondary side of the offenhauser intake, it is possible that you just aren't getting enough vacuum signal to open the secondary air valve. One option is to drill a small hole in each weight to reduce the mass so the secondary air valve will open/open quicker. Just don't go too much, then you are ordering a new secondary air valve if it opens too quick and causes the motor to stumble.


Image is of the air valve that sits between the venturies and the butterflies.
Carb is back on and runs and responds better than ever! has not been road tested yet. If it feels like the secondaries are not opening, how much do I start removing from the counter weights? I have a scale I use to weigh gunpowder (For my other hobby) and was considering weighing both sides independently and grinding them to the same weight then start removing from both sides.

my scales are graduated in Grains (1oz. = 437.5 Grains / 1Lb = 7000 grains)
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post #68 of 71 Old 07-07-2021, 10:46 AM
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That's going to be a little tricky. I'd remove tiny, tiny amounts, because you may not be able to tell about the opening by feel until they 'POP' and then you've already gone too far.
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post #69 of 71 Old 07-07-2021, 08:16 PM
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First thing is to work out how you are going to monitor or measure the opening. A vacuum gauge connected to a port just above those air valves would give a reliable indication. then drive it a bit and see what the gauges read and what your seat of pants gauge feels.

If you want to take material off, the best way is with a drill. If you put some tape round it at the desired depth, you can drill them equally quite accurately. You can then increase the drill depth or drill size.
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post #70 of 71 Old 07-08-2021, 06:14 AM Thread Starter
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Originally Posted by BagusJeep View Post
First thing is to work out how you are going to monitor or measure the opening. A vacuum gauge connected to a port just above those air valves would give a reliable indication. then drive it a bit and see what the gauges read and what your seat of pants gauge feels.

If you want to take material off, the best way is with a drill. If you put some tape round it at the desired depth, you can drill them equally quite accurately. You can then increase the drill depth or drill size.

I thought about a vacuum gauge in the cab but i feel like the friction loss will be so great it'll give seriously inaccurate readings if any readings at all.

The Yellow is the Vacuum Advance for the dist. would the White circle be the vacuum on the secondaries or will I have to put a nipple in the blue circle?

I think the Dremel with a fine stone is what I'm going to start with
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post #71 of 71 Old 07-08-2021, 06:31 AM
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I thought about a vacuum gauge in the cab but i feel like the friction loss will be so great it'll give seriously inaccurate readings if any readings at all.
You are over-thinking this. The 3-5 feet of tubing required won't affect the reading. Consider that fluid gauges (Mechanical water/ oil) depend on 5-8 feet of line to operate, and fluids have a way higher coefficient of friction than AIR).

Besides, your objective isn't a multiple decimal place accuracy...you only want to identify a point of change from a general steady reading.
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