Jump to content

Vacuum Flapper 351CJ


Recommended Posts

Alright, first attempt at a new thread, I’ve searched through the old threads and can’t seem to find the answer.

 

In the picture you can see my 351 CJ. The original air cleaner has the flapper switch (red arrow) and whatever the heck the thing is that is in the green arrow? (You tell me?)

 

Main question, the flapper valve is always open, I tried testing it by disconnecting the vacuum line from the green arrow um ... thing? And connecting it to the flapper valve, all it did was actuate the green arrow thing again as I heard a click and saw it move, but the flapper valve seems to stay open? Is there a better way to test this? To be clear, even with the vacuum disconnected the flapper stays open

 

I’m hoping to get the car to sit at cold idle a little more reliably, warm idle... sits and purs, cold idle like all old cars, not so much.

 

The car has a Holley carb with a BS electric choke, and the manifolds have been changed for headers, if this makes a difference? 

 

Cheers,

 

Dave6232-D5-AF-BBB0-4-B8-E-B80-B-9149602-B1-E0-E.jpg

Link to comment
Share on other sites

The air actuator with red arrow should be open when the engine is at operating temp. The other not sure would have to go read some. I am thinking open when the engine is warm. This air cleaner was only on CJ versions in 71 - 72 .

Since you have headers the one with the red arrow will not make much difference. Stock cast iron headers had an oven around the R.H. with a tube going up to the snorkel. When engine was cold the flapper would have been closed to pull the warm air in and when it heated up the flapper in the snorkel would open to get cooler air. 

You can test the actuators by using a brake bleeder vacuum pump should hold a vacuum. If they are leaking might be some of your rough idle when cold. They are hooked to vacuum ports on engine that are temp actuated to turn the vacuum off and on.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

Link to comment
Share on other sites

The green thing is there to let extra air in under acceleration, it should be open when the engine is off, or if when you pull the vac hose off while its running. oh and also under acceleration. its at idle when it should be closed

Link to comment
Share on other sites

I’m actually really proud of the green and red arrows... seems to have totally cleared it up!! Lol

 

Actuator ok I’ll have to test it with a vacuum pump. I didn’t think of using a manual one.

 

It’s plumbed to a temp switch of some kind an that makes sense as to why there is a space in the Cleaner for another hose ahead of the pax side pcv and behind the snorkel. 

 

The “green thing” seems to work properly. Closed at idle, I’ll have to see if it opens when it’s accelerating. 

 

Th aka for the replies fellas!

Link to comment
Share on other sites

The flapper thing is called a "vacuum motor". It closes off the inlet tube (snorkel) when cold so as David said, to allow warm air from the exhaust manifold to enter the engine for faster warm up. Once the engine reaches a certain temperature, the "vacuum thermal switch" allows the vacuum motor to open up the inlet tube to fresh air. To be honest, I am not sure of the correct name for the "air boost valve".

You can test the vacuum motor as mentioned with a hand vacuum pump. It should normally be closed and open when vacuum is applied.

How do I know this, because these parts were made in Chatham at Canadian Fram and I worked there building prototype air cleaners back in the 70's.

Geoff.

 I learn something new every day!

Link to comment
Share on other sites

That is spectacular stanglover! I feel

Slightly vindicated that you don’t know what the green thing is called either and you probably built it lol!

 

Thanks for the input!

 

My manifolds were cracked so for economy reasons it was actually easier to make the switch to flowmaster long tubes.

 

What do people think, does the hot air actually help the motor get warmed up sooner or is it sort of some 70s hocus pocus?

 

I plan to go to efi in the not to distant future for drive ability ty

Link to comment
Share on other sites

It did help to warm the engine, but the biggest reason was to improve cold weather driveability by warming the intake air and reducing condensation of the gasoline vapor in the cold intake manifold.

  • Like 1

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

Link to comment
Share on other sites

If you don't have the hot air stove on the headers/manifolds, don't waste your time trying to get the flapper to work.

 

Carbs work best within a fixed temperature range. The heat stove, flapper door and thermo-sensor in the air cleaner base work together to deliver the carburetor with air that is within that range.

 

 

D1-AZ-9-A603-A-2.jpg

 

 

Link to comment
Share on other sites

That is spectacular stanglover! I feel

Slightly vindicated that you don’t know what the green thing is called either and you probably built it lol!

 

Thanks for the input!

 

My manifolds were cracked so for economy reasons it was actually easier to make the switch to flowmaster long tubes.

 

What do people think, does the hot air actually help the motor get warmed up sooner or is it sort of some 70s hocus pocus?

 

I plan to go to efi in the not to distant future for drive ability ty

 

Pretty sure the thing that the green arrow points to is called a vacuum actuator. I did some research on it when I repainted my air cleaner. I think I found it in a Ford shop manual? Been awhile since I did that.

  • Like 1

John - 72 Q Code

Link to comment
Share on other sites

That is spectacular stanglover! I feel

Slightly vindicated that you don’t know what the green thing is called either and you probably built it lol!

 

Thanks for the input!

 

My manifolds were cracked so for economy reasons it was actually easier to make the switch to flowmaster long tubes.

 

What do people think, does the hot air actually help the motor get warmed up sooner or is it sort of some 70s hocus pocus?

 

I plan to go to efi in the not to distant future for drive ability ty

 Actually, the "green thing" was not made were I worked, but as I didn't start there until 1973, they could have been in earlier years.

Ford did most of their own stampings for air cleaner shells and lids, but Fram did all the inlets and accessories. 

As mentioned, the warm air "heat riser tube" from the manifold was intended to add warm air during the colder days. It did not really do much in warm summer months, which these days is all we drive them. So as long as your inlet tube "door" is open to fresh air all the time, don't worry about it. Your boost valve would be the only thing I would want to work. My 71 M code does not have that system, so I don't know much if anything about it.

As for EFI, your choice. To me, it's a lot of money considering the work needed to add it for the amount it saves in the long run over a good carb setup correctly. As you live basically in my neck of the woods, we are typically only able to drive from maybe mid April to the end of October and put on about 1500 -2000 Kms. a year. As I said, your choice and granted, there may be other minor benefits to EFI, just not for me.

Geoff.

 I learn something new every day!

Link to comment
Share on other sites

My thoughts on EFI are that you could buy a brand new carb every year for the next 5 years and still spend less. The EFI unit is typically only the tip of the iceberg. You then have the pump, lines and tank setup to contend with. Even if you are doing it yourself, plan on a $2k budget and several weekends of work at a minimum. From online accounts, they also don't like dual plenum intakes, so you need to account for that.

 

As an aside, I did see an install where the owner used a 5.0L Fox Mustang pump module and sender, which dropped right into the vapor separator location with a minor modification.

 

 

Link to comment
Share on other sites

Fox body pump? Interesting.

 

I think I’m a little crazy, I’ve had it out about 200 miles since March 25th? So early with the mild winter and the now completely clean roads, so I drive it all the time.

 

But that said you are right I am out a little early... later I. The year I’m hoping it will start and idle a little easier!

 

Cheers!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...