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  Topic Review (Newest First)
07-08-2021 06:31 AM
gutthans
Quote:
Originally Posted by 85Tuxedocj7 View Post
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.
07-08-2021 06:14 AM
85Tuxedocj7
Quote:
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
07-07-2021 08:16 PM
BagusJeep 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.
07-07-2021 10:46 AM
gutthans 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.
07-07-2021 09:30 AM
85Tuxedocj7
Quote:
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)
07-07-2021 09:04 AM
85Tuxedocj7
Quote:
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.
07-07-2021 08:44 AM
JEEPFELLER 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
07-06-2021 12:38 PM
85Tuxedocj7
Quote:
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???
No brake booster on this ride... not kidding. Its like stopping a freight train.
07-04-2021 11:15 AM
skypilot123
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.
07-03-2021 09:22 AM
Shawn Watson 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.


Shawn
07-03-2021 09:10 AM
gutthans
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.
07-03-2021 08:05 AM
Shawn Watson
Quote:
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???
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
07-03-2021 07:26 AM
gutthans
Quote:
Originally Posted by Shawn Watson View Post
Here's another lovely caveat to that damn split-plane intake; if you run the PCV from the back of the carb,
Shawn
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???
07-03-2021 06:36 AM
Shawn Watson Here's another lovely caveat to that damn split-plane intake; if you run the PCV from the back of the carb, you're likely to end up with the same issue because that secondary plane doesn't flow anything until you get deep enough in the throttle to open the secondaries so anything that does make it past the barely-cracked throttle plates will just bounce back and forth in the lower plane with wave reflection.

Then if you're really "lucky", there'll be a standing wave right where you spend most of your driving time and it'll actually push the gasses from your PCV right up out of the carb and turn the whole thing sooty on the outside; secondary side only.


Shawn
07-02-2021 07:15 PM
BagusJeep
Quote:
Originally Posted by gutthans View Post
Not being intimate with this particular carb, I can only suggest finding a looong straight road and gradually easing up in 4th to where the secondaries tip-in. It might also help to 'T' a (hand-held) vacuum gauge inline (if you don't have one plumbed in the cab) so you can watch for the fluctuation.
.
Excellent idea on using the vacuum gauge.

I am not familiar with this carb, is there a port you can connect to ABOVE the secondaries? If so it will show very little vacuum at that port until they open and then you will see it spike on the gauge.

Failing that you will see a drop in vaccum in the manifold when the secondaries open.
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