Bronco Aircleaner

[ArdWrknTrk]

I think more warm air is better than less cold air, and apparently Ford did as well since they put that air cleaner on the 460's

We also have to consider the inlet air temperature that Ford designed their emissions systems around.

I forget the number exactly, but seem to recall that the thermostatic vacuum control inside the air cleaner is calibrated around 105° F.

I know underhood temperatures can get much higher than that, but I also expect the truck is moving right along if the throttle wide open for long enough that the 'vent flap' is actuated.

Many places might see ambient summer temps in excess of (105) whatever the calibration temp actually is.

In the other discussion about fans and shrouds it is pointed out that at highway speed the fan isn't doing much in 'pulling' air through the radiator.

This seems (to me) to suggest that the temp delta in front/behind the radiator is less. At least less enough to begin to unlock the fan clutch.

I'm not sure what the underhood temps compared to ambient are at highway speed. Or how high the in-snorkel temps are compared to ambient given the black uninsulated stock system.

 

[Gary Lewis]

I think more warm air is better than less cold air, and apparently Ford did as well since they put that air cleaner on the 460's

We also have to consider the inlet air temperature that Ford designed their emissions systems around.

I forget the number exactly, but seem to recall that the thermostatic vacuum control inside the air cleaner is calibrated around 105° F.

I know underhood temperatures can get much higher than that, but I also expect the truck is moving right along if the throttle wide open for long enough that the 'vent flap' is actuated.

Many places might see ambient summer temps in excess of (105) whatever the calibration temp actually is.

In the other discussion about fans and shrouds it is pointed out that at highway speed the fan isn't doing much in 'pulling' air through the radiator.

This seems (to me) to suggest that the temp delta in front/behind the radiator is less. At least less enough to begin to unlock the fan clutch.

I'm not sure what the underhood temps compared to ambient are at highway speed. Or how high the in-snorkel temps are compared to ambient given the black uninsulated stock system.

Yes, 105F was the target temp for most of the trucks, as shown below, but there were others.

As for the true inlet temp, we have a link to the Carburetor Facts And Correcting Myths page on the Way Back Machine and that guy said:

Back in 1974 on my 1969 429 Galaxie 500 I installed an electric temperature gauge and several sending units: one into the air cleaner in the air stream, one just sticking out into the air by the air cleaner inlet, and another near the front grill. I used a rotary switch to flip between the sending units. Under the hood temperature on a hot day with the AC running was almost always over 200 degrees and in traffic was usually over 240 degrees. The temperature of the air inside the air cleaner was the same. Grill air temperature was never over 105. I installed a 3 inch diameter air duct from the grill to the air cleaner snorkel and was able to drop the air temperature in the air cleaner to a maximum of 175 degrees at 25 MPH in traffic and down to 120 degrees on the highway. The result was a better acceleration. Note: this was in Omaha, NE and I had to disconnect the cold air duct in the winter.

I didn't check on Big Blue when he was carbureted, but with the EFI I'm seeing essentially ambient temp at the air cleaner due to the insulation. But that air cleaner is on the fender and I don't know what temp air is actually getting to the throttle body and it is certainly higher as I don't have those hoses insulated yet - and they are very black.

[ArdWrknTrk]

Yes, 105F was the target temp for most of the trucks, as shown below, but there were others.

As for the true inlet temp, we have a link to the Carburetor Facts And Correcting Myths page on the Way Back Machine and that guy said:

Back in 1974 on my 1969 429 Galaxie 500 I installed an electric temperature gauge and several sending units: one into the air cleaner in the air stream, one just sticking out into the air by the air cleaner inlet, and another near the front grill. I used a rotary switch to flip between the sending units. Under the hood temperature on a hot day with the AC running was almost always over 200 degrees and in traffic was usually over 240 degrees. The temperature of the air inside the air cleaner was the same. Grill air temperature was never over 105. I installed a 3 inch diameter air duct from the grill to the air cleaner snorkel and was able to drop the air temperature in the air cleaner to a maximum of 175 degrees at 25 MPH in traffic and down to 120 degrees on the highway. The result was a better acceleration. Note: this was in Omaha, NE and I had to disconnect the cold air duct in the winter.

I didn't check on Big Blue when he was carbureted, but with the EFI I'm seeing essentially ambient temp at the air cleaner due to the insulation. But that air cleaner is on the fender and I don't know what temp air is actually getting to the throttle body and it is certainly higher as I don't have those hoses insulated yet - and they are very black.

Well 105(set) to 120° at highway speed, where heavy acceleration is likely to happen long enough to actuate the system doesn't seem too bad.

But the more likely scenario is being loaded on a long grade, where speed is not going to be so high.

It certainly adds a bunch of complexity!

There had to be good enough reason on the 460 for Ford to devote engineers time and manufacturing resources.

[Gary Lewis]

Well 105(set) to 120° at highway speed, where heavy acceleration is likely to happen long enough to actuate the system doesn't seem too bad.

But the more likely scenario is being loaded on a long grade, where speed is not going to be so high.

It certainly adds a bunch of complexity!

There had to be good enough reason on the 460 for Ford to devote engineers time and manufacturing resources.

Yep, to all of the above. And I think the "good enough reason" is that the 460 can draw more air than the single snorkel wants to provide, which probably leans the mix - at just the wrong time. But, introducing such warm air also leans the mix, so they must have jetted the secondaries rich.

It certainly does add a bunch of complexity as to meet emissions they had to hold the AFR pretty close, which meant they had to hold the inlet air temp pretty close - with carbs and mechanical flappers. So much easier with a computer and EFI.

EDIT: No, warm air enrichens the mix!

[ArdWrknTrk]

Yep, to all of the above. And I think the "good enough reason" is that the 460 can draw more air than the single snorkel wants to provide, which probably leans the mix - at just the wrong time. But, introducing such warm air also leans the mix, so they must have jetted the secondaries rich.

It certainly does add a bunch of complexity as to meet emissions they had to hold the AFR pretty close, which meant they had to hold the inlet air temp pretty close - with carbs and mechanical flappers. So much easier with a computer and EFI.

EDIT: No, warm air enrichens the mix!

Yes, warm air is less dense and the same as altitude compensation the fuel needs to be reduced.

But I would think a restrictive intake snorkel is going to richen the ratio, just like a choke does.

More vacuum at the boosters (which are above the throttle plate) is going to suck more fuel out of the bowl(s), through the jets.

It's certainly much easier to control pulse width at the injectors than to get a carburetor to respond properly to a wide range of demand and conditions.

[Gary Lewis]

Yes, warm air is less dense and the same as altitude compensation the fuel needs to be reduced.

But I would think a restrictive intake snorkel is going to richen the ratio, just like a choke does.

More vacuum at the boosters (which are above the throttle plate) is going to suck more fuel out of the bowl(s), through the jets.

It's certainly much easier to control pulse width at the injectors than to get a carburetor to respond properly to a wide range of demand and conditions.

Yes, I guess you are right about the snorkel enrichening the mix. The choke is a good analogy.

[Megiddo]

Yes, I guess you are right about the snorkel enrichening the mix. The choke is a good analogy.

Well, Ive got the aircleaner now. I may as well try to clean it up and see if I can get it working. Its a job I'll probably save for a bad weather day if I can ever carve down the "honey-do" list. Thanks for all the input and ideas.