I have a 351 carburetor and i broke my pcv on my valve cover, was planning on replacing my air intake(where the pcv cover connects too) with a new round one, not the risty mess i have. If i change the intake what would become of the hose? Iv seen some with little filters

 

You should have two pipes, one in each valve cover. One will have the PCV valve in it, and go to the bottom of the carb somewhere. This is the one that sucks the bad stuff out of the engine.

The other one you are talking about goes to the aircleaner. It's the air supply, as the PCV valve on the other side sucks the bad air out, fresh air comes in the other side. Most of the chrome aircleaners I have seen come with a grey plastic nipple rolling around in the box, and the bottom of the aircleaner will have a knock out. You can knock that out and mount that plastic nipple over the knock out hole, and hook your hose to that.

You can also use a chrome breather on the valve cover if you can figure out the size that fits. Be careful with using cheap chrome valve covers. Some of them do not have very good baffles over the holes we are talking about, and when the PCV sucks the bad air out, it also sucks some oil out also and you will find you engine starting to use oil.

 

If you are looking to get rid of your factory air cleaner, I'm sure there are lots of folks here more than willing to take it off of your hands....

 

On a bit of a tangent, the factory version had a separate breather filter on the edge of the air cleaner assembly. Air that would be drawn into the PCV system was taken from a point outside of the air filter. Sounds like the aftermarket version would draw from inside of the air filter.

I've never really understood why Ford did it like that, as the separate filter adds expense. Must have been a good reason, though. My hunch is it had something to do with blow-by traveling backwards through that tube on a high mileage engine, but I don't really know.

 

Amen! Like me. Here are my thoughts on that subject: Air Cleaners - ???Gary's Garagemahal

 

He is in Texas, so as long as he stays down where it's warm he will probably be ok with the open chrome unit.

 

Ok as in it doesn't get cold enough to stumble with cold air. But, having lived there I know it gets hot. So the carb will be sucking hot air instead of the cooler air from in front of the radiator. And the AFR will go rich and he will lose power. But, those open-element air cleaners look good!

 

The idea behind it was exactly that. The little cup/compartment the pcv inlet filter sits in helps catch any oil blown up through the tube and will drain back when the engine is shut off or the vacuum increases.

 

I've run open elements like this even here in -40 weather Specifically on the old green hornet (76 F250 with a 390), carb icing could be a bit of an issue at certain temps but over all no issues. I'll have to get at that truck some day and restore it is still sitting at the acreage in the back 40, it has been sitting there since 1991.

 

Very possible - if the mix at higher temps is fairly rich. But, as we've discussed, I run mine leaner than 14.7, and cold air leans it further. So at some temp it is going to be too lean to run well with an open element cleaner. Last year it got down around zero and Rusty had an off-idle stumble until I'd driven 20 miles. But, if I'd had the heat stove connected that wouldn't have happened.

Basically, the factory air cleaner system was a well-engineered way to keep the inlet air temp to the carb as close to a set temp as possible in order to allow the AFR to be tuned for emissions and/or economy. I like them for that reason and would be glad to take any of them someone wants to give me.

 

I would thnk you might be running too lean especially in an 351M/400 where they are known running hotter than desirable in cylinders 7 and 8 due to cooling issues in those cylinders and fuel distribution, if you are getting a lean stumble with colder temps that is too lean. And is increasing emissions (NOX). Lean AFR's increase combustion temps and in turn NOX and reduce engine longevity.

The factory air cleaner is not really designed to keep the inlet at a set temp it is designed to keep it from falling below a set temp. And economy was not even in the cards or they would have been much more free flowing Ford did look at this in the the early 80's When CAFE was tightening down with a ducted separate filter housing like some of the Europeans did but it was deemed to costly. These sets up did show improvements and stabilized in coming air temps better and were much better flowing, they did eventually find their way on to EFI set ups.

Open air filter elements generally are more efficient and will produce better fuel mileage and power. But also more noise and less consistent driveabilty, not exactly something that is acceptable in most production vehicles.

In most of the trucks under hoods are not an issue and an open air element will usually show improvements in both mileage and power. And if you see really cold temps you can always the swap the factory one back on in the winter that is what I used to do on the T-Bird and a few other vehicles

 

I disagree with a lot of statements in the above post.

I would run a open aircleaner on my carbed vehicles if I could, but I can't, they freeze up like clockwork in the winter. I could swap aircleaners each season but it's not worth it. And on the holley carbs(I would suspect the other 4bbl you guys like too) the aircleaner affects when the 4bbl' kick in. Put the stock aircleaner on they are going to come in earlier or as the factory intended on a stock setup. Put a open aircleaner on, and the rear barrel opening will be delayed, there is more restriction in the stock aircleaner, and it affects the signal to the diaphragm that opens the rear barrels.

 

An open air cleaner does not make the secondary's open later but the exactly the opposite, secondary opening is determined by venturi air flow/vacuum not manifold vacuum, a restrictive air cleaner will make them open later as the engine won't be able to breath properly thus able to move less air thus lowering ventri flow thus making the secondary's open later.
Not sure where you guys get some of these ideas from...... but jeeze.

With an open air cleaner they will open sooner as the engine can actually breath properly and move more CFM of air at any given RPM. There is a reason Ford and others used open air cleaners on performance applications in the 60's.


The open style air cleaners have been dyno proven to add up to ten and even more over HP over the stock units. Beside being better flowing they tend to better smooth out the air flow in to the carb with less turbulence and can actually allow for more accurate fuel metering.

And really you should be doing a pre winter tune up on carb'd vehicles that see cold temps for optimal operation. From 80F to-15F the air density change is equivalent to a 3000 ft change in altitude. Which is enough actually to warrant a jet change. Every 2000ft change in elevation is equivalent to one jet size either lean or rich depending on if you are going up or down..

Back in the day winter and spring tune ups were standard practices and you have to pull the air cleaner to do this any way so swapping from one to another is a zero time and effort job.

 

It's right here in the Holley instructions;

http://www.jegs.com/InstallationInst.../510-20-13.pdf

Third paragraph from the bottom;

In general, heavy cars require stiffer secondary diaphragm springs than light cars. Air cleaner
configuration and restriction plays an important part in spring selection, so be sure to use your
air cleaner when evaluating your vehicle’s performance after each change. An installation with
an open element air cleaner will require a weaker spring than one with a restrictive snorkel-type air
cleaner.

 

I should have been clear in the post and thought about it but did not at the time my bad for that. .
Swapping to a open filter element will allow the carb to digest more air at any given throttle "position" making the the seconday's open sooner. There is a butt in this. Induction system pressure.


Now we were talking about just restrictive inlet systems one's that are not free flowing but could provide adequate air with out actually choking the motor.
Ford systems and most Chryco V8 system fall in to this catagory more or less.

Now this goes out the window with an induction system that is actually choking the motor, such as GM's pinched snorkel where you could actually pull a vacuum in the air cleaner. This will have an impact on the vacuum in the venturi as the venturi is already in a vacuum before the ventri vaccum is calculated. . In this instance then yes going to an open air filter will make the secondary's open later as you have reduced the over all venturi vacuum at any given venturi velocity thus delaying the opening of the secondary's.

But on the flip side you are now making more power at any given throttle setting and moving more actual air at any given throttle setting. Reducing the need for the secondary's to open at lower power requirements.

Sometimes Holley has to dumb things down like choosing a PV it will get you in the ball park but is not really correct. This is another one of those things.

Having to change the secondary springs to lighter springs will apply in cases
where you are pulling a vacuum in the air cleaner. In cases where you are providing more air with out actually changing the atmospheric pressure in the air cleaner such will not be the case. I should have been more clear on this and my bad.